June 2019 Volume 17 Issue 17
NDE IN Defence and Space www.isnt.in
JUNE 2019 Volume 17 - Issue 17 ‘NDE IN DEFENCE & SPACE’
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ARTICLES - Demands and Challenges of NDE in Space, Rocket and Missile Industries
19 - Transmission Based Ultrasonic Bond Testing of CFRP Tube to Metallic End Fittings - Acoustic Emission Investigation of Metal-Ceramic Coating Fracture on Nickel Based Alloy Materials - NDE of GFRP Composite Laminates Using Single Sided NMR and Acousto-Ultrasonic Methods - Ultrasonic NDE of Large Composite Structures in Defense Applications for Fabrication Defect Identification with Quality Image Presentation
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PRODUCT GALLERY
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EVENTS
Image Courtesy
“3D Computed Tomography image of Sleeve Cast Solid Propellant grain showing cluster of voids and de-bond” HEMRL, DRDO, Pune
45 - NGC/NCB Meeting Schedule - NGC/NCB Team
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ANOUNCEMENT
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Mr. Rajul R. Parikh - Managing Editor, JNDE For JNDE SUBSCRIPTION, NEW / RENEWAL OF ISNT MEMBERSHIP INQUIRIES CONTACT:Indian Society for Non-Destructive Testing (ISNT) Modules 60 & 61, 3rd Floor, Readymade Garment Complex, SIDCO Industrial Estate, Guindy, Chennai – 600 032. India Tel: 044-2250 0412 / 4203 8175 Email: isntheadofce@gmail.com, info@isnt.in For ADVERTISEMENT INQUIRIES CONTACT:Rachna Jhaveri - JNDE Executive 8, Jyoti Wire House, 2nd Floor, Off Veera Desai Road, Near Kolsite, Andheri (W), Mumbai – 400 053. India Tel : 022 6150 3839 Email : isnt.jnde@gmail.com
PRINTED BY :- Bright Printers, Mumbai
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June 2019
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LETTERS
PRESIDENT The relationship between the JNDE and ISNT can be reciprocal, as new ideas in the field start in the Society and are subsequently expanded upon in the Journal’s pages. JNDE is responsible for selecting and presenting manuscripts that represent emerging ideas in the field. As ideas emerge, are discussed, and are adopted, ISNTshould present opportunities for these new ideas to be tested against a broader audience. The global aerospace and defence (A&D) industry is set to grow in the coming years. There are several R.J.PARDIKAR opportunities for growth, such as large-scale aerospace projects in the Asia-Pacific and European President - ISNT regions and the increasing need for advanced and automated NDT solutions, which are expected to president@isnt.org.in contribute to the growth of the market studied in the future. In India the major drivers for growth in the NDT include increasing investments in the aerospace & defence sector, increasing the complexity of machines and structures that need continual evaluation for maintaining structural integrity, and government safety regulations mandating the use of NDT techniques. The maintenance inspection of light-weight Structures (using composite materials) in Defence and Aerospace industry is a new and difficult task for non-destructive testing (NDT) which needs methods that are applicable to such high-specific-strength materials. The methods must be robust to be used in an industrial environment and sensitive enough to respond to boundaries and to provide reliable results in a short time. The new methods which fulfil such requirements are based on diverse physical phenomena e.g., heat transport, thermal expansion, air-coupled elastic waves, or non-linear vibrometry responding selectively to defects. Advaned NDT Methods such as Dynamic Thermography, Air coupled Ultrasound, Non-linear vibrometry, Computed Radiography, Dynamic interferometric methods, Fluorescence spectrometry are deployed for assessing the quality of Bonding in GFRP, Inspection of CFRP structures, inspection of smart structures, detection of loose rivets etc. X-ray-Non-destructive testing (NDT) with its ability to inspect the internal structure of objects finds many applications in the defence industries where precision, safety, quality and reliability are paramount. X-ray may be used to inspect castings, aircraft or machine parts and munitions for internal defects. In addition, security-type applications are common, including the screening of vehicles, cargo, personnel and suspect objects using either fixed or portable systems. Advanced X-ray imaging solutions for 2D systems as well as advanced 3D computed tomography (CT) applications utilising linear accelerators (linacs) as the radiation source with X-ray energies of up to 15MeV for penetrating very dense objects are deployed. I am sure that the special issue of JNDE will significantly benefit the scientists and the practitioners working in the field of Defence and Space.
I am delighted to be part of the special issue of the Journal of Non-Destructive Evaluation (JNDE) which focuses on NDE for Defence and Space sector. All of you will agree that, globally, these sectors are always a frontrunner in the technology arena. Historically, many of the major technologies used in the civil sector or other industrial sectors are usually the spinoff of the investment, research and development in these sectors. These technological sectors are usually the frontrunner in terms of the requirement of critical technologies and always BIKASH GHOSE thrives for the newer one. In these sectors, technologies get upgraded very frequently to meet the Scientist, immediate and future challenges which create space for newer systems and technologies. NDE as the High Energy Materials tool, methodology and process for the evaluation, inspection and characterization of products from Research Laboratory these sectors are no way different. (HEMRL) DRDO, Pune These sectors drive the need for specific and critical NDE technologies to meet the requirement of high bikashghose@gmail.com reliability in inspection and evaluation. Many a time there are requirements of NDE techniques in these sectors which does not have standards or pre-defined process. Hence it was thought apt to bring out an issue focusing on the NDE in the sectors of Defence and space. Almost all the major NDE technologies are being used in these sectors for various applications. There are many specific NDE technologies like Neutron Radiography, High Energy Radiography, High Power Low-Frequency Ultrasonic, Acoustic Emission, High Energy CT, Air-Coupled Ultrasonic etc are predominantly used in these sectors. This issue contains interesting papers from Space and Defence sectors. My gratitude to the authors for investing their time and contributing papers from their research outcome and also to share their experience for this special issue. It is difficult to cover all different NDE requirement in these two leading sectors in a single issue. Hope we’ll be able to bring out a few more issues specific to these sectors for presenting the broader perspective of the usage of NDE techniques for these sectors. Interesting papers in this issue covers the use of Acoustic emission, Acousto-ultrasonic, innovative NMR techniques and Ultrasonic imaging techniques for inspection of small to large size components of composite structure or multilayered structure used in combat engineering, missile or space vehicle technology. Hope these will be useful to the readers. The article which brings out the challenges ahead for inspection of the launch vehicle will also be of interest to readers. June 2019
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MANAGER & HEAD OFFICE IN-CHARGE In ISNT since 02-01-2012. Has vast knowledge and experience in Accounts, Taxation & Administration Matters. Managing day to day functioning of Head Ofce, matters connected with statutory compliance, co-ordinates with ISNT chapters and ISNT Ofce bearers, makes arrangements for meetings, guiding HO staff in their respective area of work.
ADMIN OFFICER In ISNT since 23-3-2011. In-charge of work connected with Training and Certication conducted by NCB-ISNT as per the instruction of NCB Ofce Bearers. Takes care of general correspondences and other administration matters of Head Ofce. Assisting accounts ofcer in regular matters.
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ACCOUNTS OFFICER In ISNT since 1-11 2010. In-charge of work connected with Accounts, Preparation of MIS, payment of statutory dues maintenance of accounting records, preparation of monthly income & expenditure statement and matters connected with ISNT membership.
JNDE EXECUTIVE In ISNT since 17-8-2015. In-charge of corresponding & coordinating with Editors / Authors / Chapters for write ups & managing contents of JNDE. Sourcing & handling advertisements. Coordinating payments & JNDE related matter with Head Ofce. Laying out, designing nal cover page, editing, proof reading, taking journal for nal print & handling post/mailing formalities.
June 2019
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Bangalore Chapter Shri. Sreelal Sridhar (Chairman) Outstanding Scientist & Associate Director. GTRE,DRDO, Govt. of India, Ministry of Defence, C.V.Raman Nagar, Bangalore-560093 Ph :0 9980016442 sreelal@gtre.drdo.in Shri. Shashidhar P. Pallaki (Hon. Secretary) CEO, Pallakki NDT Excellence Center No-411, A, 4th Phase, Peenya Industrial Area Banaglore - 560058 Cell:0 9448060717 pallakki@pallakkindt.com Chennai Chapter Mr. G. Ramachandran (Chairman) Chairman, ISNT Chennai Chapter New No.8, Old No:25, Desi Colony,3rd Street, Mangalapuram,Perambur, Chennai – 600 012. Phone:044 – 26622673 Mobile No.: 9600137919 Email: gr2489@rediffmail.com Shri R. Vivek (Hon. Secretary) Managing Partner, Electro-Mageld Controls & Services. "Plot No.165, Women’s Industrial Park, Sidco Industrial Estate," Vellanur, Kattur Village, Chennai – 600 062 Ph : 0 9840023015 emcs@vsnl.net / r_vivekh@yahoo.com Delhi Chapter Shri Dayaram Gupta (Chairman) Ph: 0 9891841907 Shri T. Kamaraj (Hon. Secretary) 799-Pocket - V, Mayur Vihar Phase - I, Delhi – 110 091 Ph : 0 9810364515 isntdelhi@gmail.com Hyderabad Chapter Dr. Jaiteerth R. Joshi (Chairman) Project Director LRSAM-IAC Defence R&D Laboratory, Kanchanbagh, Hyderabad, Telangana - 500058 Ph :0 9440049272 joshidrdl@gmail.com Shri M. Venkata Reddy (Hon. Secretary) Scientist, NDE Division, Defence R&D Laboratory Kanchanbagh, Hyderabad, Telangana - 500 058 Ph: 040-24583940, Cell: 9440472195 mallu.venkatareddy@gmail.com Jamshedpur Chapter Shri S. Balamurugan (Chairman) Principal Researcher & Radiological Safety Ofcer Advanced NDT Lab, NDT and Sensors Research Group. R&D and SS Division, TATA Steel Ltd., Jamshedpur-831001 Ph :0 9204651390 s.balamurugan@tatasteel.com Shri. R Shunmuga Sundaram (Hon. Secretary) Principal Researcher - Advanced NDT Lab, NDT and Sensors Research Group. R&D and SS Division, TATA Steel Ltd., Jamshedpur - 831001 rs.sundaram@tatasteel.com Kalpakkam Chapter Dr B.P.C. Rao (Chairman) Associate Director & Chief Project Engineer - QA-FRFCF & Head - QAD, IGCAR, Kalpakkam-603102 Ph : 0 9498313575 bpcrao@igcar.gov.in
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Shri N Raghu (Hon. Secretary) Head, QA-NDTS, QAD, IGCAR Kalpakkam-603 102 Ph :0 9952185927 raghu3604@gmail.com Kochi Chapter Shri C.K. Soman (Chairman) Dy. General Manager (P&U) Bharat Petroleum Corp. Ltd. (Kochi Renery) PO Ambalamugal 682 302, Ernakulam, Kochi Ph : 0 9495001014 somanck@bharatpetroleum.in Shri V. Sathyan (Hon. Secretary) Bharat Petroleum Corp. Ltd - SM (Project) (Kochi Renery) PO Ambalamugal 682 302, Ernakulam, Kochi Ph : 0 9446086345 sathyanv@bharatpetroleum.in Kolkata Chapter Shri Dipankar Gautam (Chairman) AB 121, Salt Lake, Kolkata – 700 064 Ph: 98048 13030 / 98302 03223 dgautam1956@gmail.com Shri Chandrachudha Bhattacharyya (Hon. Secretary) 28/2,Satchasi Para Lane, Kolkata-700036 Ph :0 9830251375 chandrachudha@yahoo.co.in Kota Chapter Shri Ambresh Bahl (Chairman) CE(QA), RR Site, NPCIL, PO - Anushakti, Via - Kota, Rajasthan - 323 307 Ph.01475 - 242164; Cell:0'9413351764 abahl@npcil.co.in Shri A. Varshney (Hon. Secretary) Sr. Engg. (Quality Assurance), RAPS-5&6,NPCIL, Anu Shakti, Rawatbhata, Distt.Chittorgarh. Rajasthan - 323303 Ph :0 9413358365 abhishekvarshney@npcil.co.in Mumbai Chapter Dr. Paritosh Nanekar (Chairman) Quality Assurance Division, BARC, Trombay, Mumbai – 400 085. Ph: 0'9892161750 paritoshn@yahoo.com Shri Samir K. Choksi (Hon. Secretary) Choksi Imaging Ltd., 4 & 5, Western India House, Sir P. M. Road, Fort, Mumbai- 400 001 Ph. 0 9821011113 offc@isnt.org, isntmumbai@gmail.com Nagpur Chapter Shri Jeevan Ghime (Chairman) M/s. Becquerel Industries Pvt. Ltd. 33, Rishikesh Modern Co-op. Hsg Society, Ingole Nagar, Wardha Road, Nagpur - 440 005 jeevan@biplndt.com Shri Parag W. Pathak (Hon. Secretary) M/s. NDT Solutions Saket - Pruthvi Appt, Plot No. A+B, Second Floor, Surendra Nagar, Nagpur - 440015 Ph : 0 7709047371 paragwpathak@yahoo.com
Pune Chapter Shri Mandar A. Vinze (Chairman) M/s. Vinze Magnaeld Controls Pvt. Ltd., 17 /B /16, Kothrud Industrial Area, Pune -411018 Ph :0 8308938151 chairman@isntpune.org.in Shri Bikash Ghose (Hon. Secretary) High Energy Materials Research Laboratory Defence R & D Organisation, Sutarwadi, Pune -411 021 Ph :91 9890127524 secretary@isntpune.org.in, bikashghose@yahoo.com Sriharikota Chapter Shri V Ranganathan (Chairman) Chief General Manager - Solid Propellant Plant, SDSC – SHAR, Sriharikota – 524124 Ph:- 08623-225525, M : 0 9490471915 vranga@shar.gov.in Shri B Karthikeyan (Hon. Secretary) Sci/Eng. NDT/SPROB, SDSC – SHAR, Sriharikota – 524124 Ph:- 08623-223076,223382 karthikeyan.b@shar.gov.in Tarapur Chapter Shri. N.S. Gulavani (Chairman) Ph :0'9422066789 / 0'9545436000 nsgulavani@npcil.co.in Shri Chetan Mali (Hon. Secretary) Off. Add: Scientic Assistant ‘F’ Quality Assurance Section, Tarapur Atomic Power Station 1&2, NPCIL. Ph :9420304188/8806515204 mali.chetan@rediffmail.com Trichy Chapter Shri. Revisankaran. U (Chairman) ISNT Building, Bhel Main Ofce Road, Adjacent to Institute of Engineers Building, Opp. to 79 Building of Bhel, Trichy – 620 014. Ph: 9489202949 Shri R. Raghavendrien (Hon. Secretary) Ph: 09489202949 isnt.trichy@gmail.com Trivandrum Chapter Shri G. Levin (Chairman) Group Director, PRG/PRSO, TERLS AREA VSSC, ISRO P.O, Trivandrum-695022 Ph : 0 9496050075 g_levin@vssc.gov.in Shri S. Remakanthan (Hon. Secretary) SCI/ENGR SE, NDTD / RPP, RPP AREA VSSC, ISRO P.O. Thiruvananthapuram - 695022 Ph :0 995198940 isnttvm@gmail.com Vadodara Chapter Shri. R. Venkatasubramanian (Chairman) “C/o Industrial X-Ray and Allied Radiographers (I) P. Ltd.," C-17 / 78, Krishana Industrial Estate, Opposite to BIDC, Gorwa, Vadodara-390 016 Ph : 0 9825244941 chairmanisntvc@gmail.com Shri. Kashyap Niranjan Bhatt (Hon.Secretary) Rushikesh Engineering Resources. 306, Vrajsiddhi Tower, Market Char Rasta, Rajmahel Road, Vadodara-390010, Ph : 0 9825245886 secretaryisntvc@gmail.com
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KALPAKKAM - MAY 2019 20th - 24th May 2019 - ISNT Kalpakkam Chapter, is organizing “Dr. Baldev Raj Memorial Bridge Course on Nondestructive Evaluation and Quality Assurance (BRM-BCNQ 2019)” at IGCAR, for the benet of pan India engineering students entering the nal year of their B. E./B.Tech/ M.E./M.Tech. The objective of this course is to introduce advanced NDE technologies and more importantly,
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providing practical hands on experience in state-of-the-art NDE equipments available at IGCAR. This bridge course is a step towards capacity building so that the participating students will be able to plan towards a successful career in professions involving NDE and QA. Participation in this bridge course will enable the students to gain all necessary knowledge in the area of advanced NDE, to be able to take up any NDE assignment effectively, be it in research or industry or academics. their families. 35 people attended the program.
DELHI - JANUARY TO MARCH 2019 Ÿ 19th January 2019 - EC meeting was held. Ÿ 21st April 2019 - EC Meeting was held. ISNT Day was celebrated on same day by our chapter with members &
EC Meeting
CHENNAI - MARCH TO MAY 2019 24th March 2019 - Technical talk titled Automated Digital Radiography new paradigms was held. The talk was delivered by Prof.Krishnan Balasubramanian, Chair Professor in Dept. of Mech Engg., Head CNDE, IIT, Chennai. 35 members attended the technical talk and it was well received with several clarications sought by the members present. ii. Technical talk titled Quality Planning in Fabrication of Pressure Equipment was held. The talk was delivered by Shri.Parthapratim Brahma, Lloyd Register Asia, Chennai. 65 members attended the technical talk and it was well received with several clarications sought by the members present. Ÿ Executive committee meeting was held on the same day. Ÿ ISNT DAY CELEBRATION - ISNT DAY was celebrated in a grand manner at Hotel Palm Grove on 21st April 2019, in evening. Around 165 members with spouse and children attended. The Chief Guest of the day was Prof. Dr. M.K. Surappa, Vice Chancellor of Anna University, Guindy. He addressed the gathering about NDT in Academic and various Industrial Applications. Audience were highly impressed & appreciative for his speech. Tamil Speaker Sri. Arul Prakash gave an entertaining and educative speech. His speech was mesmerizing. It was well received by the audience. All Faculties, Examiners, Lab, Equipment Providers and Staff members were honoured during this celebration. Memento and shield were presented by Prof. Dr. M.K. Surappa, Vice Chancellor of Anna University. The Best Member Award “Thambithurai Award” sponsored by M/s. Electro-Mageld Controls & Services was awarded to Shri. T.V. Navanithakrishnan. The Best Technical talk award “Rajamani Award” sponsored by M/s. Electro-Mageld Controls & Service was awarded to Dr. Sivarama Sarma Ÿ
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29th June 2019 - AGM and Election for new committee has been planned.
Members at the ISNT Day celebration
and Mr. S.G.N. Murthy. The Best Participation Award “Pari Award” sponsored by M/s. QTECH was awarded to Mr. Nitesh Kumar of BPCL, Kochi. Magic and entertainment was conducted by Mr. Chandrasekar and well received from the children and gathering. Mr.RG. Ganesan was the convener and Mr.S.R.Ravindran supported him. Ÿ 28th April 2019 - Executive committee meeting was held. COURSES CONDUCTED DURING MARCH & APRIL 2019 Sr. No
Name of the course
Course Dates
Course Director
Examiner
No of participants Course Exam
1 VT Level-II
03.04.19 to 08.04.19
Shri E.Sathya R. Chandran Srinivasan
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23
2 PT Level-II
09.04.19 to 13.04.19
Shri E.Sathya Srinivasan
P. Anandan
23
23
Shri. E.Sathya MT & PT L- 24.04.19 to 03.05.19 M.Manimohan Srinivasan II
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FUTURE PLANS I. Radiographic Testing Level-II course and exam from 15th May 2019 to 25th May 2019. ii. Ultrasonic Testing Level-II course and exam from 5th June 2019 to 15th June 2019. iii. Eddy Current Testing Level-II course and exam from 26th June to 6th July 2019. iv. Visual Testing Level-II course and exam from 22nd July to 27th July 2019. v. Surface NDT (MT & PT) Level-II course and exam from 1st August 2019 to 10th August 2019. vi. Radiographic Testing Level-II course and exam from 21st August 2019 to 31st August 2019. June 2019
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Awards
Mementos to faculties
Mr.RG.Ganesan, Convener welcoming the gathering
Invocation song
Welcome speech by Mr.G.Ramachandran, Chairman ISNT Chennai Chapter
Gathering
Mr.B.Ram Prakash Chairman Elect talking about ISNT Activities
Mr.G.Ramchandran giving bouquet to Prof.Dr.M.K.Surappa, Chief Guest
Mr.R.Vivek, Hon. Secretary announcing the Award Winners
Mr.K.Viswanathan giving bouquet to Mr.Arul Prakash, Tamil Speaker
Mr.S.Subramanian felicitating Mr.Arul Prakash with shawl
Chief Guest Address by Prof.Dr.M.K.Surappa, Vice Chancellor, Anna University
Gathering
Mr.T.V.Navanithakrishnan receiving the Best Member Award
Dr.B.Sivarama Sarma receiving the Best Technical Talk Award
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Mr.SGN.Murthy receiving the Best Technical Talk Award
Mr.B.Ram Prakash receiving the Memento for faculty
Mr.RG.Ganesan receiving the Memento for faculty and equipment providers
Mr.V.Pari receiving the memento for Lab providers
Mr.R.Vivek receiving the Memento for faculty and lab provider
Memento to Chief Guest Prof.Dr.M.K.Surappa by chapter members
Mr.T.V.Navanithakrishnan introducing the Tamil Speaker Mr.Arul Prakash
Mr. Arul Prakash giving speech
Mr.V.Pari giving vote of thanks to Chief Guest and Tamil speaker
Magic show
Kids performing during entertainment programme
Audience engrossed during entertainment programme
THIRUVANANTHAPURAM - JANUARY TO MAY 2019 Ÿ 2nd January 2019 - During this period Young Engineers forum of ISNT Thiruvananthapuram organized two technical lectures at Hotel Chirag Inn. Shri Agilan, VSSC delivered a talk on "Friction Stir welding of Al Alloys and NDT” and Shri Madheswaran, VSSC delivered a talk on Material characterization of composite products by NDT. The lectures were well received by participants. Ÿ 6th Feb 2019 and 10th April 2019 - Two EC meetings of the chapter were held. Local organizing committee was constituted for organizing the upcoming Seminar on NDE and Metrology – SENDAM 2019 in May 2019. www.isnt.in
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‘ISNT DAY’ Celebration - ISNT DAY 2019 was celebrated by ISNT Thiruvananthapuram chapter at Hotel Chirag Inn in a grand manner on 24th April 2019. Shri A Shunmugavel, Former Secretary briefed about the signicance of the celebration. Shri G Levin, Chairman, ISNT Thiruvananthapuram chapter & Deputy Director, VSSC inaugurated the programme. In his inaugural address, he mentioned about the objectives of ISNT and recalled the efforts of the society for the last 20 years towards promotion of scientic development in the area of non-destructive evaluation and quality consciousness. He appreciated the efforts taken by all chapter members comprising of eminent personalities in NDT eld and young talents who volunteered themselves to take over the challenges in June 2019
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organizing events to propagate the knowledge of NDE. He proudly informed about the importance given by our chapter to the technical content in any programs organized. Shri Arumugam, Vice Chairman, ISNT Thiruvananthapuram Chapter & Group Director, Quality Control and NDE group, LPSC, delivered a talk on ‘Computed Metro Tomography for NDE and Metrology’.
Prof. Unnikrishnan Nayar, IISER, Trivandrum facilitating the speaker Shri Madheswaran G, VSSC
Shri M Arumugam, Group Director, Quality control and NDE group, LPSC, Thiruvanathapuram delivering talk
The lecture was loaded with comprehensive technical information about CT, the results of studies carried out at ISRO and the features of latest equipment purchased by LPSC, Trivandrum. The interactive lecture was well received by the participants and further raised the curiosity of the participants. The programme was followed by dinner.
Shri Agilan, VSSC delivering the technical lecture
Participants at the lecture
Shri G Levin, Chairman, ISNT Thiruvanthapuram chapter inaugurating the ISNT Day celebration
Dr. R.M Muthiah, VSSC (Rtd.) giving memento to Shri Arumugam M
brief presentation on ISNT PUNE - JANUARY TO APRIL 2019 and the prominent activities ISNT DAY Celebration - For the very rst time, ISNT Pune carried out since last 1 year Chapter celebrated raising day of ISNT (ISNT Day) on 21st April till date. Shri Bhausaheb 2019. On this occasion an evening programme was organised at Pangare, urged all the Hotel Raviraj, Bhandarkar Road, Pune for the ISNT Pune Chapter members to contribute to the Members along with the family members. More than 35 ISNT society for spreading the members and family members attended the evening programme knowledge of NDE science. held during 1830 - 2200 hrs. The programme was started with Shri Bikash Ghose gave a felicitation of the past president of ISNT, Shri S I Sanklecha in the presentation on "Mission hand of Shri Mandar Vinze, Chairman of ISNT Pune Chapter. Shri Past President, ISNT, S h a k t i " w h i c h w a s Shri SI Sanklecha felicitated Vinze also felicitated Shri Bhausaheb Pangare, Past Chairman conducted by India on 27th by Sri M A Vinze, Chairman ISNT Pune Chapter and Shri M S Shendkar, immediate past March 2019 using the chairman of ISNT Pune Chapter present during the evening ISNT Pune Chapter information available in function with oral bouquet. Shri Mandar Vinze gave the public domain. He explained about the mission criticality, welcome address and thanked all the EC members and members technological challenges and importance of the mission of of Pune Chapter for their active support for growth of Chapter Anti Satellite Test for the Country. The topic of talk had and attaining the prominence in the National level. He thanked created curiosity and interest among the members and and remembered all the past dignitaries for their contributions to family members. Shri Kalesh Nerurkar, Hon Treasurer & EC ISNT due to which ISNT gained the prominence across the globe. member of Pune Chapter gave vote of thanks. The family Shri Sunil Gophan, Chairman-elect of Pune Chapter requested function concluded with delicious dinner. Family members Shri S I Sanclecha to brief about the journey of ISNT. Shri thanked ISNT for conducting the programme of general Sanclecha gave a brief outline regarding the journey of ISNT & interest and expressed their eagerness to join with the ISNT described how two societies came together and formed the the day celebration every year. The event was sponsored by M/s society, ISNT, as it stands today. He expressed his happiness Vinze Magnaeld Controls Pvt Ltd, Pune. regarding the growth of ISNT over the years and also expressed satisfaction that ISNT is in the able hands of experienced Ÿ 10th January 2019 - Meeting of Woman empowerment committee was organised at Hotel President on 10th January stalwarts and dynamic young minds. Shri Bikash Ghose, Jt 2019. The meeting was well attended by more than Secretary, ISNT & Hon Secretary ISNT Pune Chapter gave a June 2019
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22 participants from various organisations. Dr R J Pardikar had chaired the meeting. Chairman of Woman empowerment committee Mrs Navita Gupta, ISNT Vice President Shri D D Joshi, Chairman of Pune Chapter Shri Mandar Vinze, Hon Secertary of ISNT Pune Chapter Shri Biaksh Ghose were present in the meeting. The evening meeting was sponsored by Insight Quality Services, Pune.1 Ÿ 6th January 2019 - An MOU between ISNT and Maharashtra Institute of Technology-World Peace University (MIT-WPU) was signed by President ISNT Dr R J Pardikar, Prof I K Bhatt, Vice Chancellor, MIT-WPU and Shri Mandar Vinze, Chairman ISNT Pune Chapter. The event was organised at the ofce of Vice Chancellor MIT-WPU, Pune. ISNT Pune chapter is designated as the nodal chapter for the execution of the activities related to the MOU. Ÿ 15th February 2019 - An evening technical talk was organised at Hotel Raviraj, Pune. The talk on "General requirements for the competence of testing and calibration laboratories - Review of ISO 17025" was delivered by Dr Thomas Zavadil, Dy General Director of ATG, Czech Republic.
Dr Zavadil also spoke about the upcoming NDT qualication system ASME ANDE-1. 50 people attended the evening technical talk. Ÿ 17th March 2019 - An NDT awareness programme was conducted at ADCET, Ashta, the student chapter afliated to ISNT Pune Chapter. The programme was conducted by Shri Uday B Kale and Shri Kalesh Nerurkar & attended by 35 students. Ÿ 23rd March 2019 - One day Training session was conducted by the Women Empowerment committee in association with ISNT Pune Chapter at Bharati Vidyapeeth Pune. The talk was delivered by Mrs Mugdha Joshi Kale and co-ordinated by Mrs Sangita Kapote. Ÿ 4th & 5th April 2019 - Two days awareness programme Workshop on Non-Destructive Evaluation (NDE) was conducted at Metallurgical Department of Govt Polytechnic, Pune. About 50 students of 2nd year and 50 students of 3rd year Metallurgical Department attended the programme. The programme was co-ordinated and conducted by Shri B B Mate.
Members attended the Women Empowerment Committee
MOU being signed by Prof I K Bhatt, VC MIT-WPU and Dr R J Pardikar, President ISNT
MOU signed being exchanged between President ISNT and VC MITWPU
Audience attending the programme
Dr Zavadil delivering talk
Students attending the NDT Awareness Programme
Students with the the Co-ordinators from ISNT Pune Chapter after the NDT Awareness programme
Mugdha Joshi delivering talk during training session
Programme in progress
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MUMBAI - FEBRUARY TO APRIL 2019 4th to 8th February 2019 - RT LEVEL III course was held . 11th to 15th February 2019 - UT level III course was held. 18th to 22nd February 2019 - Basic level III course was held. Ÿ 25th to 27th February 2019 - MT level III course was held.
2nd to 4th March 2019 - PT level III course was held. 18th to 20th March 2019 - Testing of Electrical Equipment and NDT course was held. Ÿ 25th to 29th March 2019 - RT level I course was held. Ÿ 11th to 15th April 2019 - ET level III course was held.
TARAPUR - APRIL TO MAY 2019 14th May 2019 - Seminar cum Technical talk on Ultrasonic technique PAUT, TOFD & TFM was held at Hotel Silver Avenue Banquet hall, Boisar. This event was organized in association with M/s Eddy Technologies, Dubai. Total 34 ISNT life members attended the programme. Programme was very informative and appreciated by all members.
Same day, demonstration on different equipment were also arranged on different NDT technique such as PAUT, TOFD and TFM as well as Corrosion under insulation. Ÿ Advertisement for new membership enrolment was announced to R & D Center, Tarapur, TAPS 1&2, TAPS 3&4 NPCIL and MIDC area. Ÿ Two EC meetings were held during April - May period.
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Mr. Anupamkumar, M/s Eddify Technolgies, Dubai giving presentation
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Chairman ISNT Tarapur at Demonstration on Corrosion under insulation equipments
ISNT Tarapur Team with Eddy Technologies representatives
Mr. Jitendrakumar Yadav, M/s Eddify Technolgies, Dubai giving talk on Advanced UT technique
Mr. Shriniwaskumar, M/s Eddify Technolgies, Dubai giving talk on TFM
WORLD NEWS ASNT Rolls Out New NDT Qualication Program in Houston The American Society for Nondestructive Testing (ASNT) has announced Industry Sector Qualication (ISQ) for Oil & Gas, a new nondestructive testing (NDT) qualication program for the oil and gas sector. The purpose of the ISQ program is to provide the oil and gas industry with NDT personnel who have demonstrated competency in practical application of a specic technique through hands-on per formance demonstration qualication examinations. The program will launch in June 2019 and will only be available at one facility in Houston for now. ASNT is initially developing four ultrasonic testing (UT) technique qualications that can be used as standalone qualications or incorporated into an employer-based program. Additional technique exams will be added to meet industry needs as dened by participating oil and gas owner/operators. June 2019
During the initial program launch, the rst technique to roll out will be UT Thickness, which emphasizes the candidate's ability to distinguish wall loss from laminations and accurately measure remaining wall thickness, potentially savings hundreds of thousands of dollars in repairs or loss of production. Shear Wave, Phased Array, and Time Of Flight Diffraction (TOFD) for ASME weld quality will follow. According to ASNT, a full rollout of the program in the United States will take place in the last quarter of 2019, followed by the international market in 2020.
“Courtesy & Source : www.asnt.org”
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ARTICLES
ARTICLES
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Demands and Challenges of NDE in Space, Rocket and Missile Industries P.V. Sai Suryanarayana D.G.M. (Retd.), Solid Propellant Space Booster Plant. SDSC SHAR, ISRO, Sriharikota. Email : sai895956@gmail.com 1.0
INTRODUCTION
S
olid rocket motors (SRMs) are the main components which impart the initial upward boost to either a Satellite launch vehicle or a missile. In the rocket fraternity the satisfactory performance of SRM itself is considered as half success of the total Mission and such is the importance of SRM. The qualification of SRMs is always a challenge owing to their large size, complex configuration and unique shape. Although several NDE methods and techniques are in place to ensure a defect-free product, there are still certain grey areas which are yet to be explored. Especially considering the unique functioning environment and demands thereof, there is an urgent need to improvise/innovate NDE methods or develop newer techniques so as to match the ground-realities. Problems are all the more compounded whenever composite materials are involved in the configuration of SRMs. This paper highlights some of the challenging areas in NDE of SRMs which need to be addressed to further enhance the reliability of performance of SRMs in any given situation. 2.0 COMPLEXITIES OF SOLID ROCKET MOTORS SRMs are huge in size ranging from a few mm to around 3 m in diameter, lengths up to about 10 m and the weights up to several tons. A typical motor consists of an outer metal or composite casing which is internally bonded to solid propellant through layers of rubber insulation and adhesive material. There is also another important interface between propellant and end-inhibitor, which is provided to prevent propellant burning at end faces and designed for only radial burning. The propellant may be of either cylindrical or star-shaped depending on the ballistic requirements as shown in Fig 1. Though there is a possibility for several types of defects that can occur such as voids, porosity, delamination in insulator layers, etc., the most harmful ones are cracks in the propellant and debonds between different interfaces like hardware to insulator and insulator to propellant. Besides at the manufacture stage, these defects may also creep in during handling, transportation and storage of SRMs. If the critical defects are left undetected, they lead to malfunctioning of the SRM which in turn may cause failure of the total mission itself. Unlike other engineering products, SRMs perform only once as Space or Missile mission is a single-shot-affair. Thus, the critical defects have to be detected with maximum probability and condence levels. June 2019
Case Insulation Propellant Port
CYLINDRICAL PORT
Nozzle
Fig.1. Typical SRM conguration with cylindrical port
3.0 EFFECT OF DEFECTS IN THE PERFORMANCE OF SRMS The manufacturing process of SRM is a complex one involving different materials coupled with chemical processes. As shown in Fig.1, the periphery of the motor comprises of interfaces involving metals/composites, rubber and organic adhesives. As mentioned earlier, the two critical defects, viz., interfacial debonds and cracks occur at periphery and propellant regions respectively. These defects, if present increase the burning front during propellant combustion causing increase in surface area of ame front. This results in shoot-up of rocket chamber pressure which leads to failure, in case the pressure becomes more than the designed value. Fig.2 illustrates the propagation of these two types of defects during combustion of SRMs.
Fig.2 – Typical aw propagation during SRM combustion
Thus, it is imperative that the above two critical defects shall be detected with maximum probability any time before the article is cleared for either static testing or the ight mission.
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Fig.3. Tangential RT set-up for checking interfacial bonding
Fig.4 Normal or Grain RT set-up for checking propellant integrity
Additionally, separate coverage is provided to check the inter face between end-inhibitor and propellant. The radiographic image of this interface presents an ambiguous picture as the interface sometimes appears as a dark line, making us to believe that there is a debond. Whereas many a time the dark line happens to be due interfacial porosity arising due to the nature of the resin used in the preparation of the inhibitor. Of late this, ambiguity has been satisfactorily resolved in ISRO by using Acousto-Ultrasonic technique with very low frequency probes. However, if there are curved congurations as in certain SRM segments such as domes, this technique is not consistent as of now. The custom-made Acousto-Ultrasonic equipment with specially made probes is shown in Fig.5.
Fig.5. Acousto-Ultrasonic Equipment for evaluation of lowdensity material interfaces
5.0 DEMANDS OF NDE IN THE PRESENT SCENARIO After the production of solid rocket motors, it may or may not be used immediately or within a reasonable period. Especially missile motors have to be transported and stored in hostile environments till they are drawn for use. During their storage and subsequent use, periodically, there is a need to ensure the health of the motor in good condition. Most of the times the SRM has to be brought to High Energy Radiography Facility for re-NDT which is several hundred kilometers away from the storage site. It is not only a cumbersome and time-consuming exercise but also the article is subjected to repeated loads of handling and road-transportation. In order to avoid this ordeal, there is a need to develop a portable NDE technique such as UT www.isnt.in
or AUS as shown in Fig.5, which shall be capable of encompassing all the following existing unexplored grey areas of NDE vis-à-vis solid rocket motors. a. Checking the second interface below the rocket casing, i.e., the interface between rubber insulators to propellant at all regions, including ultrasonic imaging option (Presently there is work in progress in ISRO to address this issue.) b. Evaluation of propellant to inhibitor interface at domed regions c. Complete Ultrasonic Evaluation of Composite-cased solid rocket motors; d. Ultrasonic in-situ evaluation of complete propellant grain including imaging option; e. In-situ evaluation of joint regions of segments; f. Determination of Mechanical properties by NDE; g. Evaluation of composite liners of nozzles in assembled condition; It is the dream of all NDT practitioners involved in production of SRMs used in Space and Missile programmes to realize suitable NDE methods to address above unresolved issues. If the above listed grey areas are successfully addressed, we can say that the science and technology of NDE has come of age vis-à-vis, the complex objects called solid rocket motors. 6.0 CONCLUSION Like in any other engineering industries, in Space and Missile industries also, NDT started as a limited quality control tool to check the integrity of end products. Over a period of time, NDT has metamorphosed as a means of NDI and later NDE to expand the scope of quality evaluation. If and when, the above listed unexplored areas of SRMs are addressed successfully, we can condently say that we have come to the stage of replacing the term NDE with NDC, that is “Non-Destructive Characterization” of SRMs. ACKNOWLEDGEMENT The author would like to express his sincere thanks to Dr. Bikash Ghose, HEMRL, for giving an opportunity to write this paper. REFERENCES [1] Varian, M/s, ‘High Energy X-Ray applications in NDT“ Palo Alto California, USA. [2] Leo P. Dolan and Robert L.Torkildsen, “Nondestructive Inspection of Minuteman Engines in support of Flight Testing”, Proceedings of Bureau of Naval Weapons, Missiles and Rockets Symposium, Concord, California, 1961. [3] Viswanathan, K., “High Energy Radiation“, Report No. ISRO-SHAR-TR-08-18-84, January, 1984. [4] Ravindran, V.K., Sai Suryanarayana, P.V. et.al., “ NDE of Solid Rocket Motor Critical Interfaces using Long-Range Ultrasonic Testing ”National Conference on Non-Destructive Evaluation-NDE-2015, Hyderabad. June 2019
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4. 0 PRESENT NDE PRACTICE FOR SRM QUALIFICATION Due to their large size and complex conguration, the only viable NDT method suitable for SRMs is the High Energy Radiography using Linear Accelerator (LINAC). Two types of techniques viz., tangential radiography and normal radiography are routinely employed to check interfaces and propellant mass respectively. Fig.3 and 4 show the RT set-up for these two radiography techniques.
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Probes
We offer wide range of transducers for various applications such as Flaw Detection, Thickness Gauging & Material Research. Our standard range includes: Contact normal beam transducers, Dual element transducers, Angle beam transducers, Immersion transducers (Focused / Non-focused) & Transducers with replaceable delay line/angle wedges
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Transmission Based Ultrasonic Bond Testing of CFRP Tube to Metallic End Fittings S. Hari Krishna1*, S. Sridhar1, KM Usha2, CR Bijudas3, H. Priyadarshan 4, A. Rajarajan1 Composites Entity, Vikram Sarabhai Space Centre, Trivandrum, Kerala, India 2 Department of Biotechnology and Biochemical Engineering, Mohandas College of Engineering and Technology, Trivandrum, Kerala, India 3 Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala, India 4 Department of Avionics, Indian Institute of Space Science and Technology, Trivandrum, Kerala, India 1 *Email : shkris@rediffmail.com, Phone: +91-8289993358 1
ABSTRACT Carbon bre reinforced plastic (CFRP) tubes are used in various launch vehicle and spacecraft applications because of their weight advantages over metals. For integration of these tubes with other components, they are preferably bonded with metallic end ttings. Non-destructive testing (NDT) of these bonds is an important activity for the assessment of quality of the joints. This paper presents a methodology of using transmission based ultrasonic testing which is able to detect kissing disbond between tube to end tting, which could not be detected by other standard NDT methods. Keywords: CFRP tubes, end tting, disbond, ultrasonic testing, transmission method. 1.0
INTRODUCTION
I
n the space and transportation sectors, composite tubes made of carbon fibre reinforced plastics (CFRP) are used because of their weight advantage over metals [1,2]. Properties of these tubes are a function of the resin & fiber system; orientation & volume fraction (i.e. proportion) of fibres and manufacturing methods. Properties can easily be tailored to meet the requirements for specific applications. For integration with other tubes/parts, the composite tubes can be either bonded or mechanically fastened [3]. Bonding is preferred over mechanical fastening wherever possible [4]. However, it requires tight control of bonding process and proper evaluation. Information provided by NDT after the bonding process; detection of the onset/growth of disbond(s) if any, at different stages of qualification/acceptance tests plays a major role in product quality assurance. Ultrasonic pulse echo testing is one option for NDT of the bond interface [5]. However, this technique cannot be used if either bond interface echo or the echo from the total thickness of bonded joint cannot be obtained. Such a situation can arise due to tubes with lower levels of compaction. Usage of low frequency ultrasonics in pitch catch mode is another option [6]. Other options include thermography and laser shearography [5]. In this paper an alternate approach for bond testing based on ultrasonic transmission-based technique is explained. Comparison of the results is done with those obtained by the low frequency ultrasonics in the pitch catch mode. Ultrasonic pulseecho testing could not be used for the tube joint evaluation as the interface echo could not be obtained because of lower compaction levels of tubes, which are oven cured. Pulsed thermography and laser shearography using thermal excitation also could not detect the defects in these joints because of lower compaction levels, higher curvature and higher thickness of the tubes. www.isnt.in
2.0 TUBE TO END FITTING JOINT CONFIGURATION AND THEORY OF DEFECT DETECTION A typical joint between CFRP tube (Figure 1b) to an Aluminium metallic end fitting (Figure 1a) is chosen for the studies. Schematic of joint configuration is shown in Fig 1.
Figure 1a. Metallic end fitting
Figure 1b. CFRP tube
Figure 1 . Schematic of tube to end fitting joint configuration
Figure 2. Schematic of tube to end fitting joint configuration
2.1 Low Frequency Ultrasonic Pitch-Catch Technique In the pitch-catch technique, one probe transmits (pitches) a burst of acoustic energy into the test part and a second probe receives (catches) the transmitted energy through the test part [7]. Bond condition beneath the two transducer tips affects the characteristics of acoustic energy that is transmitted between the tips. These characteristics can be displayed in terms of phase and/or amplitude. The relative amplitudes of the signals are a function of the impedance mismatch at the bond interfaces. For a bond condition, a portion of the acoustic energy transmitted into the tube is attenuated at the bond interface, resulting in a lower signal energy transmission to the receiver (Figure 3a). In a disbond condition, the transmission through bond interface is less because of higher impedance mismatch between tube and air interface, resulting in the higher acoustic energy transmission to the receiver (Figure 3b). June 2019
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Figure 3a. Bond condition
Figure 3b. Disbond condition
Figure 3. Defect detection principle of pitch catch technique
2.2. Ultrasonic transmission technique In the proposed transmission technique, the transmitter is placed on the flange region of a metallic fitting and the receiver is placed on the surface of the composite tube, as shown in . The transmitted ultrasonic waves are guided along the metallic end fitting. At the tube to end fitting interface, a portion of these guided waves are transmitted (or leaked) into the CFRP tube in case of bond, as shown in Figure 4a. The transmission levels come down in case of disbond, as shown in Figure 4b. Received signal is displayed on the monitor of ultrasonic equipment.
Figure 4a. Bond condition
Figure 4b. Disbond condition
Figure 4. Defect detection principle of Transmission technique
The signal consists of many peaks which correspond to the multiple modes of guided waves, which cannot be easily resolved. However, based on the total energy (i.e. envelope) of received signal rather than a single peak, comparison and distinction between good and disbond regions is made. 3.0 EXPERIMENTAL DETAILS The CFRP tubes used in the studies were made of 28 number of uni-directional carbon prepreg layers rolled over a metallic mandrel, layer by layer. After the final prepreg layer, a plastic film was overwrapped; and final consolidation was done by a dry Kevlar hoop layer. After consolidation, the tubes were oven cured. The tubes (Figure 1b) have a nominal diameter of 40 mm and thickness of 3.5 mm. For the disbond detection studies, two numbers of the tubes were bonded with Aluminium end fittings (Figure1a) on either side of them using Araldite. Tube No 1
Type of defect Partial disbond
Creation method No application of Araldite at a location
Initially both end fittings were Full disbond with bonded. Afterwards, the tube was pull 2 interference type of tested. The pulled-out end fitting was fit (kissing disbond) then reinserted (by force) creating interference type of fit. Table 1: Defect types June 2019
Two types of interface defects were planned. Table 1 gives defect types and their creation methods. For pitch-catch testing, Bond Tester S-21R from M/s Zetec, US was used. The probe used consists of two plastic tipped piezoelectric transducers separated by a distance of ½ inch. With a nominal frequency of 25 kHz and point tipped plastic probes in pitch-catch mode, the waves that propagate through the tubes are plate (Lamb) waves for disbond detection. The test parameters were ne tuned to get a maximum difference between bond and disbond conditions. The interface areas of all four metallic end ttings were tested with the optimum settings. For the transmission testing, Dr yscan 410D equipment from M/s Sonatest PLC, U.K and two numbers of ¼ inch diameter, 5 MHz frequency probes from M/s Olympus, US were used. Probe selection is primarily guided by the curvature of the tube and the probe seating area available on the metallic end tting. Vacuum grease was used for coupling the transmitter to the metallic end tting. Silicone rubber was used for the dry coupling of the receiver for placing on the tube surface. Subsequently, trials were carried out by varying different receiver lter frequencies. Optimum lter frequency was observed to be 1 MHz for the chosen combination of probes. Lower lter frequencies of 0.25 and 0.5 MHz could not distinguish the interference type of defects whereas higher frequencies of 2.25 MHz and above had very high attenuation of the signal. For bond interface assessment, transmitter was placed at a location on the ange portion of metallic end tting. Receiver was moved along the axial direction on the surface of tube. By moving the transmitter around the circumference of the ange portion, the entire tube surface corresponding to bond interface area was covered. As the separation distance between transmitter and receiver was increased, reduced signal amplitude envelope was observed, because of higher attenuation. This factor was accounted for, for comparison of signals between bond and disbond locations. 4.0 RESULTS AND DISCUSSION 4.1. Tube with partial disbond Pitch catch method using Bond Tester could distinguish the bond and disbond locations. Typical signals obtained at bond and disbond locations are shown in Figure 5. The transmission method also could distinguish the disbond location (Figure 6). Defect areas mapped by both methods matched within 1 mm, which is acceptable because of manual mode testing. In pitch catch technique (Figure 7), no disbond indications could be obtained in the entire interface area of the kissing disbond except at two smaller portions. Figure 7b shows the signals obtained in the kissing disbond area. The area hatched in white is the disbond area, and within this area, a small portion denoted by red boundary is an area identied as defective. The total area identied as defective by this method amounts to nearly 8% of the interface area. After reinserting pulled out end tting back into the tube, these small areas might have sufcient gap/clearance that could be detected by this method. www.isnt.in
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Figure 5a. Bond condition
Figure 5b. Disbond condition
Figure 5: Results on partial disbond tube using pitch catch method
Figure 6a. Bond condition
Figure 6b. Disbond condition
Figure 6: Results on partial disbond tube using transmission method
Figure 7b. Kissing Disbond condition
Figure 7: Results on kissing disbond tube using pitch catch method
Figure 8a. Bond condition
Figure 8b. Disbond condition
Figure 8: Results on kissing disbond tube using transmission method
Transmission method could clearly distinguish the difference between the two end ttings ( Figure 8 ). Entire tube surface corresponding to the kissing disbond interface could be mapped by this method. It can be seen that both methods use guided waves. In the pitch catch method, two transducers, which are separated by a xed distance are used to test the bond condition, by placing them on the surface of the tube. Variation in the energy reected from the bond interface is used for defect detection.
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5.0 CONCLUSIONS The proposed transmission based ultrasonic testing could detect disbonds in the interface of CFRP tube to metallic end ttings. While other standard NDT methods had limitations, this method is able to distinguish the kissing disbond simulated between tube to end tting. ACKNOWLEDGEMENTS The authors wish to thank the colleagues of Composites NDT Division, and colleagues of Composites Entity for their support in carr ying out the studies. Thanks to Director, VSSC for permitting to publish this paper.
4.2. Tube with kissing disbond
Figure 7a. Bond condition
In the transmission method, one transducer is placed on the metallic end tting; the second transducer is placed on the surface of the tube. Distance between the two transducers is varied till the bond area is covered. Defect detection is by the variation in energy transmitted across the bond interface, while accounting the attenuation factor due to separation distance between the transducers. Increased sensitivity of transmission method is due to the higher frequency of ultrasonic waves used in comparison to that of pitch catch method. Considering the tube thickness, increase of frequency in pitch catch method cannot be done, as it makes the plate waves as surface waves, which cannot be used for bond inter face evaluation. Transmission technique allows use of higher frequencies, whose upper limit is decided by the attenuation factor.
REFERENCES [1]. "Fabrication methods", Composites World, 2006, Available on https://www.compositesworld.com/articles/fabricationmethods [2]. J. D. Soler et al., "Design and construction of a carbon ber gondola for the SPIDER balloon-borne telescope", 2014, arXiv:1407.1881 [astro-ph.IM] [3]. Weber A, "New Techniques for Joining Plastic to M e t a l " , A S S E M B L Y, 2 0 1 4 , A v a i l a b l e o n https://www.assemblymag.com/articles/92408-newtechniques-for-joining-plastic-to-metal [4]. Avinash Parashar, Pierre Mertiny, "Adhesively bonded composite tubular joints: Review", International Journal of Adhesion & Adhesives, 2018, 58-68. [5]. Flávio Buiochi et al., "Ultrasonic System for Automatic Detection of Disbonds in Composite Tube Joints", 21st Brazilian Congress of Mechanical Engineering - COBEM 2011. 2011, Natal, RN, Brazil. [6]. Karthikeyan P, N. Narayanankutty, Thomas C Koshy, "Application of Low Frequency Ultrasonics for the Evaluation of Integrity of Bonded Composite Structures", National Conference on Non Destructive Evaluation - NDE 2005, 2005, Kolkata, India [7]. Practice No. PT-TE-1422, "Ultrasonic testing of aerospace materials", Preferred Reliability Practices, NASA.
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Acoustic Emission Investigation of Metal-Ceramic Coating Fracture on Nickel Based Alloy Materials B. Binu1, Anoop Kumar Shukla2, K. K. Purushothaman3, Jeby Philip4 Experimental Mechanics Division, STR Entity, Vikram Sarabhai Space Centre,ISRO, Trivandrum 2 Special Metallurgical Facilities, MME Entity, Vikram Sarabhai Space Centre, ISRO, Trivandrum Email: 1b_binu@vssc.gov.in 1,3,4
ABSTRACT Nickel based super alloys are used for components exposed to higher temperature in rocket engines. Protective coatings are provided on engine components as part of functional requirements. Coupon level tests are being carried out as part of the characterization of protective coatings before being applied on component level. Acoustic emission (AE) was employed to study the process of crack initiation and propagation in metal-ceramic protective coatings on Nickel based super alloys. AE monitoring was carried out during the three-point bending test of at specimens made of two types of Ni based alloys with protective coating to evaluate the adhesion strength. Linear location mode analysis has been employed to segregate the genuine AE events from the centre region of the specimen at which the cracks were originated. Pattern recognition technique has been used to distinguish the AE due to coating failure and noise signals due to the rubbing of rollers. The deformations on the ceramic coating, initiation of cracks and its propagation has been characterized based on the identied AE parameters amplitude, duration, energy and counts. Keywords: Acoustic Emission (AE) technique, protective coating, crack growth, amplitude, energy, counts 1.0
N
INTRODUCTION
ew generation rocket engines like Semi-Cryo engines require materials with superior mechanical and thermal properties and have ability to perform in different operating conditions such as fuel-rich or oxidizer rich environments. The metals can ignite in presence of oxygen at high temperature and high pressure. To survive in such environment, the metal either should inherently have superior ignition resistance or should be provided with an external coating to protect the base metal. As the application requires elevated temperature strength and creep resistance, Ni based super alloy materials have been selected for the fabrication of such rocket engine components. For the Nickel based super alloys, metal-ceramic coatings are used as a protective coating for the base metal from degradation in oxygen rich environments. Oxide ceramics have very good oxidation resistance as well as high temperature stability. Ceramics are also known for their very good erosion resistance. However, ceramics are brittle materials and have low coefficient of thermal expansion compared to metals. The large difference in coefficient of thermal expansion between the base metal and coating may lead to poor adhesion of the ceramic coating to metallic substrates. This can be addressed by having metallic content (Ni for the intended application) in the coating powder. Coating is applied by making slurry of powders. Visual Inspection is employed to examine any surface cracks on the specimen and eddy current method is used for the coating thickness measurement. Usually the coating thickness is of the order of 100-200µm [1]. Various types of tests are to be conducted to establish the required properties for the coatings. The adhesion strength, thermal shock resistance, erosion resistance etc. of the coating is characterized through coupon level tests. The characterization of adhesive strength and of maximum allowable strain during mechanical loading of such coated material is of great importance to optimize the method June 2019
of coating application [1]. The adhesion strength of the coating is examined using tensile testing/ bending test. The mechanical integrity of coating during three point bend test was examined at room temperature. The conventional microscopic tools are not effective for the detection of all possible failure sources in real time during the load tests and we can investigate the cracking of the coatings only after the completion of mechanical loading. [2]. AE non-destructive technique is widely used for detecting the damage processes in engineering materials in real time [3]. The AE signals generated during the crack extension processes are captured using piezo-electric sensors mounted on the surface of the structure and processed using a data acquisition system. Various studies have been carried out towards the detection of micro-cracks in coating and its extension under stress by AE. It is demonstrated that the fracture of the Nickel-copper-coating on the carbon-ber reinforced plastic specimens could be successfully investigated using AE [2]. It is reported that the total AE event count during Brinell indentation tests are related to the porosity of plasma sprayed alumina coatings [4]. During Coupon level tests, the major difculty is the segregation of the genuine AE signals of degradation of coating from the noise signals from machine and other experimental setup. In the three point bending test, three rollers are used, in which two rollers were placed on either side to support the sample and the load is applied through the roller placed above the samples at the center. Hence the emissions due to the movement of rollers over the sample also will merge with the genuine AE data. The emission due to such disturbances has been eliminated using linear location mode analysis in which the source emissions from the area of interest alone has been re-plotted by applying suitable event lock out values. The located events from the center region of the specimen, where the coating failures are expected is separated for further analysis work. Data from the center region of the samples are a combination of different failure mechanisms. www.isnt.in
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For the detailed behavioral study, AE signals corresponding to different failure mechanisms are to be segregated. The clustering using pattern recognition method is found to be the best tool for separating the AE events corresponding to various failure mechanisms [5]. In pattern recognition technique, based on the similarity in different AE parameters, the data set is to be separated and forms different cluster groups [6]. The objects in each cluster will be similar. There are two types of pattern recognition method viz. supervised and unsupervised. The clustering is done through supervised algorithms. The commonly used algorithms are KMeans, Max-Min distance, Forgy, Cluster Seeking, Isodata etc. [7]. In this work the fast iterative k- means algorithm is used for the clustering. In this work, commercially available “NOESIS” software is used for the clustering through pattern recognition method. 2.0 EXPERIMENTAL PROCEDURE As part of the study, two samples were tested. The samples were made of two different type of Nickel based super alloys with thicknesses 2mm for sample-1 and 3mm for sample-2 (ref Figs 1a and 1b). The lengths of the samples are 115mm and width is 20mm. The samples were coated by spray method as per the standard procedure for metal-ceramic coating. Three layers of coating were applied to get the desired thickness of 130 to 140µm. Subsequently the samples were dried and then red in a furnace having inert gas medium (Argon) at a temperature of 1000ºC to obtain the desired mechanical properties. a
b
c
d
Fig.1. Photograph of samples (a) 2mm thick sample No.1 (b) 3mm thick sample No.2 (c) samples instrumented with AE sensors (d) samples loaded in UTM machine & digital camera
The samples are tested in INSTRON make UTM machine. The samples were placed on two rollers on small edges of the sample on either side in such a way that, the coating surface of the sample was on the bottom side. One roller was placed at the center on which the loads were applied. Digital camera recording was employed to capture the real-time coating failure. The time of load application and camera recording are synchronized to nd out the exact load at which the coating degradation initiated. The photograph of the sample and experimental set up is shown in Figs 1c and 1d. Real time AE monitoring was carried out during the bending test. Two 150kHz resonant frequency piezoelectric AE sensors (make Physical Acoustic Corporation) were deployed on the un coated surface of the samples. www.isnt.in
The sensors were xed at a distance of 30mm from the center of the samples. The sensors were xed using glue. PAC make 2/4/6 model preampliers were used for amplication. Data acquisition was carried out though standard 30m long RG58 Co-axial cables. Mistras make SAMOS boards are used for the real-time data acquisition. The sensitivity of the sensors are checked using Hsu-Nielsen pencil-lead breaks in which simulated AE signals are produced by breaking 0.5 mm, 2H pencil leads near to the sensors. NOESIS pattern recognition software supplied by PAC, USA was used for the post-test data analysis. 3.0 RESULTS & DISCUSSION Two coated samples made of two different Nickel alloy material with 2mm and 3mm thicknesses were loaded to different load levels. Their AE was recorded throughout the testing and assessment has been carried out afterwards. The fracture of coating at the center was captured in digital camera. The images had shown the visible cracks at the center where the maximum stress level occurs and the simultaneous delamination between the coating and substrate extended towards both sides as shown in Fig.2.
Fig.2. Photographs of the sample after the load test
Fig. 3. Filtering of Noise signals sthrough Linear Location mode event generation (a) Total data captured from sample-1 (b) segregated AE from the cracked region of Sample-1 (c) Total data captured from sample-2 (d) segregated AE from the cracked region of Sample-2
Figs 3a and 3c shows the located AE source events broadly distributed over the coated area but highest peak of RMS value were registered at the center where maximum damage level observed on the coating. Higher peaks of RMS above 0.005 has occurred near the supporting side rollers also along with rubbing noise signals and this attributed to the coating damage near the inner supports. The emissions on other regions of the sample is the combination of various mechanisms viz. the deformations/ micro-mechanical activities/ delamination of coating, deformations of the metallic sample, rubbing noises etc. June 2019
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Since the digital camera image shows the initiation of visible cracks at the center region of the samples, the study was concentrated on the emissions originated from that region alone and the segregated data is shown in Figs 3b and 3d. To understand the behavior of the AE under loading, the amplitude of AE signals captured during the entire loading and the segregated AE signals from the cracked regions of the samples were plotted against load. The entire test data for sample 1 & 2 (Figs 4a & 4c) shows a large number of AE hits from the initial phase of load application itself. But in Figs 4b and 4d the extracted data didn’t show much emissions in the initial loading phase as expected and this indicates that these initial phase signals are not related to the fracture of coating and is due to the extraneous disturbances. The crack formation in ceramic coating is reported to be brittle fracture phenomena. The metal-ceramic coating is expected to have lower ductility due to ceramic materials in it. During loading metal-ceramic is expected to experience plastic deformation after the yield point of the substrate. Two modes of failure expected for the coating are, delamination of coating from substrate and the cracking of coating. The coating side of the samples are under tension during the bending test and micro cracks will develop on the coating at lower strain level and crack will grow on further loading. Simultaneously extensive delamination’s can also occur below the coating. At higher strain levels macro cracks will evolve in the maximum strain region [3].
Fig. 4. Amplitude, Load vs Time plots (a) Total hits captured from sample-1 (b) segregated AE hits from the cracked region of Sample-1 (c) Total hits captured from sample-2 (d) segregated AE hits from the cracked region of Sample-2
Sample-1 data (Fig 4b) shows a few signals with low magnitudes initiated around 200s corresponding to a load of 500N and subsequently a trend change in AE occurred around 320s corresponding to a load of around 1000N. Similar trend occurred in sample -2 also for a load of 1200 and 1400N. When the trend change occurred, the intensity of AE activity drastically increased and also the magnitude of AE parameters increased. This indicates that the emissions with lesser intensity in the initial loading phases are due to the elastic deformations of coating and which lead to micro-cracks. On further loading the micro-cracks grow to macro level which give rise to a higher intensity emissions. The captured digital camera images shows the initiation of crack and degradation exactly matching with the trend changes occurred in AE activity. June 2019
To understand the failure mechanisms, the data sets extracted from the samples were investigated by unsupervised pattern recognition through clustering algorithms after removing the very low energy signals of value <1 which is due to the rubbing noises. The respective data set was partitioned into clusters using k- means algorithms available in NOESIS software. kmeans is the simple clustering algorithm, which divides n objects into k clusters in which each object belongs to the cluster with the nearest mean. The data points with similar features will form a cluster [6]. Different methods are used to identify the best-suited cluster numbers for a data set. One method is to calculate the ratio of heuristic criteria R & T. Davies and Bouldin defined the R criterion, which is the mean value of the ratios calculated from average within cluster distance to the distance between any pair of clusters. Bow defined the T criterion, which is the ratio of the minimum distance between any pair of clusters to the maximum of the average within cluster distances. Hence the better discrimination will give by minimizing the R-value and maximizing the T value ie. the R/Ď&#x201E; ratio should be minimum for a best suited cluster[7].
Fig. 5. Number of clusters formed in Sample 1 &2 using k-means algorithm
To understand the correlation between the number of clusters and different failure mechanisms, the fundamental AE parameters duration, energy & counts were plotted with respect to time as shown in Fig.6. Different clusters are shown in different colors. AE belonging to cluster-1 contains large number of signals initiated from the beginning of loading itself and broadly distributed over the samples. A significant growth in signals and its magnitude observed at certain load at which the cluster-2 also initiated. The magnitudes of different AE parameters are showing lesser values and this cluster is attributed to the elastic deformations on coating and subsequent micromechanical activity/ delamination prior to cracking. The cluster has been broadly distributed over the coated area. Due to the extensive micro cracking and simultaneous delamination activity occurred during loading, a large number of AE signals will produce which is comparatively more than the AE signals produced during the crack propagation. AE signals belonging to cluster-2, are showing the higher magnitude in all AE parameters. It is reported that the higher intensity AE signals are aroused during rapid crack propagation [8]. The AE sources of cluster 2 are located in the center region of samples, which is the maximum stressed region. Correlation with the images from digital camera shows that these high intensity emissions are occurred at the time of initiation of macro cracks at the center region of the samples. Therefore it is opined that, the signals of this cluster-2 could be due to the macroscopic crack propagation. There is a difference in overall magnitude of AE parameters are seen between the samples but the trend in both the samples are similar.
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4.0 CONCLUSION The investigation carried out on the acoustic emission data of metal-ceramic coated Nickel alloy samples shows that, the initiation and cracking of the protective coating on the base metal could be detected in real-time using AE. Pattern recognition method is found to be the best tool for segregating the AE signals corresponding to different failure modes like initiation of micro-cracks, delamination and subsequent failure of the protective coating. Even though a difference in overall magnitude of AE parameters corresponding to the failure mechanisms in two different samples is seen, the AE pattern of both the samples are found to be similar. The signature, corresponding to the various failure mechanisms of the coating fracture has been characterized based on fundamental AE parameters. This will help to predict the on-set of failure mechanism of similar coating on different alloys.
Fig. 6. Characterization of Clusters (a, b, c) energy, duration, count plots for sample-1 (d, e, f) energy, duration, count plots for sample-2
The AE signals belonging to cluster 3 shows that, they are few in number and exhibit lower magnitude in all AE parameters. Increasing tendency in the signal magnitudes are seen after some time after the peaking of the cluster-2. It is already reported that the elasto-plastic deformations of the metals will give lower intensity emissions compare to crack growth signals [9]. Since these signals are not seen in the initial loading phase, but initiated after coating fracture and varying with respect to load, these signals are not from the coating and is attributed to the initiation of yielding of the base metal. These inference is made on basis of the data from two samples and more detailed study is to be carried out in future. As a part of characterization of the failure mechanism on the coating fracture the magnitudes of different AE parameters corresponding to different clusters for both samples were compiled and studied as shown in below Table.
AE Parameer
Class 1 (Micro-mechanical activity/delamination)
Sample 1 Sample 2
Class 2 (Cracking of coating)
Sample 1
Sample 2
40-70
40-75
Class 3 (Deformation of base metal)
Sample 1 Sample 2
Amplitude (dB)
35-65
35-65
Duration (μsec)
1-2500
1-3500
Energy
1-40
1-50
10-120
10-500
1-5
1-10
Counts
1-300
1-400
20-500
20-2000
10-100
10-150
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35-50
35-60
2500-6000 3000-12000 200-900 300-1200
ACKNOWLEDGEMENT We acknowledge Shri. Praveen.P.S, Technical Ofcer-C, Shri. Shripati Ingale, Senior Technical Assistant, EXMD,VSSC supporting staff SMF, VSSC and the testing team MCD, VSSC for their whole hearted support and efforts put for completing the work. REFERENCES [1] Deepak Dinesh, A K Shukla 2015, Specication document for Metal-Ceramic coating for Semi-Cryo Engine components. [2] Markus G. R. Sause, Daniel Schultheiß and Siegfried Horn, Aacoustic Emission investigation of coating fracture and delamination in hybrid carbon ber reinforced plastic structures. [3] Sergey A. Nikulin, Vladislav G. Khanzhin, Andrey B. Rozhnov, Alexander V. Babukin and Vladislav A. Belov, Analysis of crack resistance and quality of thin coatings by Acoustic Emission, Int. J.Microstructure and Materials Properties, Vol. 1, Nos. 3/4, 2006. [4] S. Safai, H. Herman and K. Ono, Acoustic emission study of thermal-sprayed oxide coatings, American Ceramic Society Bulletin, 58, 1979, 624. [5] A. A. Anastassopoulos and T. P. Philippidis, “Clustering Methodology for the Evaluation of Acoustic Emission from Composites”, Journal of Acoustic Emission, 13, 11–21 (1995). [6] Pattern Recognition techniques for Acoustic Emission based condition assessment of unred pressure vessels Envirocoustics S.A., El. Venizelou 7 & Delfon, 144 52 Athens, Greece. [7] Anto Zacharias, B Binu, K K Purushothaman, Jeby Philip, Acoustic Emission Signal Analysis of 15CDV6 Pressure Vessel Using Pattern Recognition Method NDE 2014. [8] J. Miguel, J. Guilemany, B. Mellor and Y. Xu, “Acoustic emission study on WC/Co thermal sprayed coatings”, Materials Science and Engineering A, Vol. 352, pp. 55–63 (2003). [9] B Binu, K K Purushothaman, Jeby Philip Acoustic Emission Signal Analysis to Study the Yield Behaviour of AA2219 Aluminium Alloy Material, NDE 2014.
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NDE of GFRP Composite Laminates Using Single Sided NMR and Acousto-Ultrasonic Methods S K Sahoo1,2*, R N Rao1, Srinivas Kuchipudi2, Y L V D Prasad2 and M K Buragohain2 Department of Mechanical Engineering, National Institute of Technology, Warangal-506 004 2 Advanced Systems Laboratory, DRDO, Kanchanbagh PO, Hyderabad-500 058 *Corresponding Author Email: sahoosanjayk@rediffmail.com 1
ABSTRACT Glass ber reinforced plastics (GFRP) composites are being used in many industrial applications. Often, GFRP composite structures are used along with rubber lining in space and defence applications and also in oil and gas pipe industry. Rubber is adhesively bonded to composite inner surface to meet the requirements. The interface of GFRP composite and rubber lining is very critical. Any de-bond (separation of adhesively bonded liner from composite surface) at the interface may lead to failure of composite structure due to corrosive gases and liquids. Non-destructive Evaluation (NDE) of such structures is challenging due to their high attenuation of ultrasound and poor radiography defect signatures. NDE methods such as nuclear magnetic resonance (NMR) imaging and Acousto-Ultrasonic are being developed for their advantages and high resolution for defect detection. The present study reports application of proton single sided NMR method to evaluate the de-bonds of rubber liner with composite. Results are compared with Acousto-Ultrasonic method, which uses low frequency mechanical waves for inspection. Results indicate application of both these techniques for evaluation of bonded interfaces. Advantages of both the techniques over conventional techniques have been discussed. Keywords: NDE; composite; NMR; ultrasonic, de-bond. 1.0
F
INTRODUCTION
iber reinforced Composite cylindrical structures with polymer matrix have wide industrial and civilian applications. Often such structures are protected from corrosive environments using rubber/elastomeric layers. These layers are adhesively bonded to the composite structure for structural purposes. Integrity of these adhesively bonded layers is important to serve the intended purposes such as oil transportation or hot gases or other industrial uses. During usage, these adhesively bonded structures have to be nondestructively evaluated to avoid the possible failures due to defects such as de-bond and voids. Composite structure can fail catastrophically due to weakening of strength when defects occur. Such failures have been reported earlier in literature. Non-destructive evaluation (NDE) of such adhesively bonded structures using various physics based techniques has been of interest to both industry as well as NDE engineers. Reliable NDE methods for bond quality evaluation for both diagnosis and prognosis of bonded interfaces has been topic of research in industry. Any de-bond at the interface may weaken the structure due to uneven erosion of rubber liner leading to opening of lining, thus exposing composite materials. Many NDE methods are being used to access the bond quality. However, increased reliability of bond quality is both a requirement as well as necessity to take decision about replacement of the structure. Ultrasonic, X-ray radiography and Fokker bondtester are widely used for bonded interfaces. These techniques have limitations in measuring the thickness of the bond. Both qualitative and quantitative techniques are required for taking decision for replacement of the structure. Advanced NDE techniques such as bondtesters and mechanical impedance analyzers require standard reference specimen for comparison of the data for taking decision. Special techniques are required to meet field requirements. June 2019
Proton single sided NMR (SSNMR) technique uses chemical signature of the material present within rubber to identify the signature of the presence or absence of chemical composition of the adhesive at the interface [1-10]. The present study is focused on developing NMR methods for defect detection in at glass/epoxy composite lined with rubber. Proton single sided NMR system is unique as compared to conventional NMR systems wherein samples are to be taken in vials and inserted into the bore of the magnet to achieve magnetisation whereas SSNMR system magnetic eld is outside the magnet due to the special assembly of the permanent magnets so as to generate magnetic eld outside the core of the magnets. By superimposing AC magnetic eld over DC magnetic eld, a sensitive volume is generated which can be moved inside the sample by shifting magnets using stepper motor assembly/set up. This was rst demonstrated by Prof. B. Blumich group of Germany. Later on many other commercial systems were made available for research purpose. The present study uses commercially available SSNMR system for NDE applications. Advantages of proton single sided inspection are detailed below:Ÿ Single sided inspection access of only one side of structure is required Ÿ Non-contact inspection Ÿ No couplant is required during inspection Ÿ Safe for operator Ÿ Portable can be used on shop oor Ÿ Qualitative and quantitative assessment of defect is possible Results of proton NMR technique were compared with low frequency Acousto-ultrasonic method. Ultrasonic methods have been widely applied in industry and many new methods have been reported in literature. Low frequency Acousto-ultrasonic scanning (AUS) is an emerging NDE technique for characterizing and inspecting composite structures with multi-layered congurations. www.isnt.in
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The technique uses low frequency ultrasonic waves to interrogate the composite structures. It needs only one side access and no couplant is required during the inspection. With the use of tone burst excitation and single frequency in cyclic sinusoidal excitation, it was demonstrated that it is possible to penetrate deeper into the composite structures through the multiple interfaces to achieve the NDE of the composite structures.[11-18] The following features of AUS make it suitable and challenging NDE tool over the conventional NDE techniques: Ÿ Ability to penetrate thick multi-layered composite structures Ÿ Inspection of elastomeric interfaces Ÿ No couplant is required during testing Ÿ Testing can be done from one side Ÿ Single sided (reection method) or single sided (pitch catch method) inspection Ÿ Provides contact mode or non-contact mode of testing Ÿ Cost effective inspection setup Areas of application of AUS include bond-quality evaluation, determining thickness variation and defect detection. Inspection of glass/epoxy composite with known inserted defects by proton single sided NDE technique and low frequency ultrasonic methods are presented in this paper. The inspection procedure discussed in the paper has much potential space and defence applications including inspection of Radome of aircraft, inspection of case bonded composite pressure vessels. Other applications include, composite structural components such as re-entry vehicle structures of missile systems and heat shields. 2.0 FA B R I C AT I O N O F G L A S S / E P OX Y COMPOSITE STRUCTURE The glass/epoxy composite laminates were fabricated using lament winding process on at metallic mould using hoop winding process. The fabrication process involves winding glass laments under tension over the rotating at mandrel. The mandrel rotates around the spindle while a delivery eye on a carriage traverses horizontally in line with the axis of the rotating mandrel, laying down bers in the desired hoop winding pattern. The glass laments are impregnated in a bath with epoxy resin as they are wound on to the mandrel. Once the mandrel is completely covered to the desired thickness, the component is sent for curing in an oven. After the component is cured, the mandrel is removed by cutting from the template using diamond cutting machine. Nitrile based rubber of 2 mm thick is used as insulation. Rubber based adhesive is used for bonding glass/epoxy at laminate with rubber insulation. Defects such as de-bond/air-gap (Defect-1), foreign material inclusion (Defect-2) and wrinkles/folds in rubber (Defect-3) are taken for studies as shown in Figure 1. 2mm Rubber
200 mm
Defect-2
Defect-3
Defect-1
300 mm
Fig.1. Schematic of at GFRP test laminate www.isnt.in
4mm GFRP
3.0 EXPERIMENTAL WORK Proton single sided prole NMR Mouse system is based on the principle of inside-out NMR where the sample is outside the magnet. These systems are provided with stepper motor for precise lifting of magnets to magnetize the region of interest inside the sample. For the present studies, we have used commercially available proton solid state NMR system with 12.88 MHz RF frequency. The prole NMR-MOUSE (PM 25) is a portable open NMR sensor equipped with a permanent magnet (Bo equivalent to 0.3T) geometry that generates a highly uniform gradient perpendicular to the scanning surface outside the magnets. Figure 2 shows solid state proton single sided portable NMR system (PM 25) used for the present work. A at sensitive volume is excited and detected by a surface RF coil (frequency 12.88 MHz) placed on top of the magnet at a position that denes the maximum penetration depth into the sample. By repositioning the sensitive slice across the object, this scanner produces one-dimensional proles of the sample with a spatial resolution of 30 μm. Saturation recovery and Carr-Purcell-Meiboom-Gill (CPMG) pulse sequences were used for determining the T1 and T2 relaxation times respectively. The present study reports results from experiments performed with CPMG pulse sequence at pre-dened position programmed using PROSPA software. The sensor excites a sensitive volume at a xed distance from the magnet surface as per the program. By mechanically moving the sensor, the sensitive volume is stepped through the sample and the CPMG sequence is then applied at each position with an echo-time of 60 µs. Then signal from each position is plotted as amplitude versus depth plot to generate depth prole of the sample.
Fig. 2. Prole NMR system with sample on the top.
Fi g . 3 . A c o u s t o ultrasonic system used for testing Glass/epoxy structure with rubber insulation.
The experimental setup for low frequency Acousto-ultrasonic inspection consists of tone burst excitation pulser and broad band receiver system (frequency range of 10 KHz to 20 MHz) along with pre-amplier electronics and low frequency ultrasonic probes. The entire electronics and back-up power supply is housed in safety certied composite enclosure. The system is portable for testing at the shop oor. The test signals were captured in A-scan mode for further analysis. In A-scan mode, amplitude versus time of ight of tone burst excitation received using broad band receiver is captured. Two cycles of sinusoidal burst of 50 kHz frequency is used for testing. One probe for excitation and other probe for receiving were used in pitch catch mode. Figure 3 above shows the Acousto-ultrasonic system used for the present study. June 2019
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CPMG sequence is used for obtaining data at each of the depth during prole experiments. From the CPMG fast data, normalized peak integral value is plotted as a function of depth. Figure 4 (a) and (b) shows normalized peak integral value of glass/epoxy sample bonded with rocasin rubber as a function of depth (in microns) and weighted function of normalised peaks respectively. Depth prole data shows no signature of glass/epoxy sample whereas adhesive-rocasin rubber interface show steep increase in amplitude at the depth corresponding of 4 mm. This is because of low proton signature from epoxy resin, it may also be noted that glass ber does not have protons. Hence no signal is obtained from composite sample. Whereas the signal from rubber is observed until the entire thickness of the rubber is scanned. Beyond rubber thickness of 2 mm, the signal value falls to baseline indicating absence of protons beyond the rubber material. Weighted function of amplitude of peaks versus depth also clearly indicates the signature of rubber. From the weighted function, we can clearly ascertain the thickness of rubber layers. depth (81/81)
depth (82/81)
0.20 0.4
0.3
w [(1,8 ), (9, 16 )]
Amplitude
0.15
0.10
0.05
0.2
0.1
0.0
0.00 8000
6000
4000
2000
8000
Depth (um)
6000
4000
2000
Depth (um)
Fig.4. (a) and (b) Prole NMR data at defect free zone
From the figure 6 (a) and (b) the signature of rubber and its thickness can easily be ascertained. There is no notable change in the signature of the rubber, however the depth of the rubber is observed to be shifted to higher values indicating the presence of airgap when compared with figure 4 (a) and (b).The airgap thickness can be calculated from the shifted value taken from the X-axis. In this case, the airgap thickness is 1200 µm + 30 µm.
Fig.7 AUS data at defect zone 1 (De-bond)
Figure 7 shows the aucosto ultrasonic data of the test sample over the defect region (de-bond). It is observed to show increase in amplitude as compared to the figure 5 (non-defect region). This is due to the increased energy of the ultrasound due to reflection from de-bond. In case of the bonded zone, energy of the ultrasound gets attenuated whereas over the debond zone, the ultrasonic energy gets reflected back from the interface and more energy is received at the receiver end. Similarly, other areas of the glass/epoxy laminate were also inspected. At zone 2, defect (suspected presence of ceramic powder) was observed to be present as shown in figure 8(a) and (b). depth (81/81)
depth (82/81)
0.4
w [(1 ,8 ),(9 ,1 6 )]
Amplitude
0.15
0.10
0.05
8000
6000
4000
Depth (um)
Figure 5 above shows Acousto-ultrasonic data of the test laminate over the defect free region. Number of bunch of ultrasonic signals received at the receiver in pitch catch mode is observed. The signal is characteristic of the sample on a defect free zone. depth (82/81) 0.4
0.15
0.3
w [(1,8 ), (9, 16 )]
Amplitude
depth (81/81) 0.20
0.10
0.05
0.2
0.1
0.0
0.00 8000
6000
4000
Depth (um)
2000
8000
6000
4000
2000
Depth (um)
Fig.6 (a) and (b) Prole NMR data at defect zone 1 (De-bond)
Experiments were again performed on test laminate on other zones with suspected defects. Figure 6(a) and (b) shows normalized peak integral value of glass/epoxy sample bonded with rocasin rubber as a function of depth (in microns) and weighted function of normalized peaks respectively at defect zone marked as zone 1. June 2019
0.2
0.1
0.0
0.00
Fig.5. AUS data at defect free zone
0.3
2000
8000
6000
4000
2000
Depth (um)
Fig.8 (a) and (b) Profile NMR data at defect zone 2 (chalk or ceramic powder)
The defect was visually appearing as white patch, but nature of the defect is not known. From the NMR signatures there was no proton chemical signature obtained over the defect region, this indicates the material is not polymer and has finite thickness of about 900 µm+30 µm. Since, there is no proton NMR signature the foreign material is suspected to be ceramic powder. Figure 9 below shows Acousto-ultrasonic data over the zone 2 of the test laminate. Defect signature indicates that the defect is not air-gap and there is no shift in time stamp of the signal. However the increased amplitude of the signal indicates presence of defect with lower density than the composite. It is further confirmed from the NMR data that defect has no protons, hence it may be concluded that defect may be foreign material with no protons and has lower density. Glass/epoxy laminate was further tested at other suspected defect zones. At zone 3, profile NMR data was obtained as a function of depth. Figure 10(a) and (b) shows normalized peak integral value of glass/epoxy sample bonded with rocasin rubber as a function of depth (in microns) www.isnt.in
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Fig.9 AUS data at defect zone 2 (Chalk or ceramic powder)
and weighted function of normalized peaks respectively at defect zone marked as zone 3. Figure 10(a) shows characteristic peak in the prole data at a depth of 6000 μm indicating increased proton density at that point as compared to defect free sample (see gure 4(a) above). depth (81/81)
depth (82/81) 0.5 0.4
w [(1,8),(9 ,16 )]
Amplitude
0.15
0.10
0.05
0.3 0.2 0.1 0.0
0.00 8000
6000
4000
Depth (um)
2000
8000
6000
4000
2000
Depth (um)
Fig.10 (a) and (b) Prole NMR data at defect zone 3 (Wrinkles or fold)
Fig.11 AUS data at defect zone 3 (Wrinkles or fold)
Figure 11 above shows Acousto-ultrasonic data over defective region. Signal shows multiple peaks appearing over time domain indicating multiple reections occurring from different regions. 4.0 CONCLUSION Single sided prole NMR technique is observed to be qualitative as well as quantitative NDE tool for evaluating bond-quality of glass/epoxy-rubber bonded interfaces. Defects such as airgaps, thickness of rubber layers, presence of foreign material and wrinkles within rubber layers were qualitatively and quantitatively evaluated. Acousto-ultrasonic inspection method works as a complementary NDE tool with defect information obtained qualitatively. Both the techniques are safe to be used on the shop oor for qualitative and quantitative assessment of defects. ACKNOWLEDGEMENTS The authors are thankful to the Director, ASL for providing an opportunity, support and encouragement to carry out this work. www.isnt.in
REFERENCES [1] Manoj K Buragohain, Composite Structures: Design, Mechanics, Analysis, Manufacturing and Testing, CRC Press, 2017. [2] Sanjay K Mazumdar,Composites Manufacturing: Materials, Product, and Process Engineering, CRC Press, 2002, ISBN 0-8493-0585-3. [3] P K Mallick,Fiber-reinforced Composites: Materials, Manufacturing, and Design, Taylor & Francis Group, USA, 2008, ISBN-13: 978-0-8493-4205-9. [4] Kim Jang-Kyo,Engineered Interfaces in Fibrereinforced Composites, Elsevier Publications, 1998, ISBN 0-08042695-6. [5] P T Callaghan,Principles of Nuclear Magnetic Resonance Microscopy, Claredon Press: Oxford, 1993. [6] K Saalwachter, Chain Dynamics in elastomers as investigated by proton NMR, Macromolecules, 2006, Vol. 39, pp. 3291-3303. [7] B Blücmich,NMR Imaging of Materials, Oxford University Press: Oxford, 1992. [8] R Dykstra, R T Callaghan, D Eccles and MHunter,Portable NMR systems for Non Destructive Testing, Non-destructive testing Australia, 2005, Vol. 1, pp 15-18. [9] F Casanova, J Perlo, B Blumich,Single sided NMR, Springer-Verlag, Berlin, 2011, ISBN 978-3-642-16306-7. [10] K Srinivas et al, Single sided NMR for NDE of GFRP – rubber interface, The e-Journal of Non-destrustive testing- ISSN 1435-4934, Vol.20 No.6 (June 2015). [11] P K Raju,Acousto-ultrasonic technique for nondestructive evaluation of composites and structures, The journal of the acoustical society of America, 102, 3082 (1997) [12] S Mareeswaran and T Sasikumar,The Acousto Ultrasonic Technique: A Review, International Journal of Mechanical Engineering and Technology, 8(6), 2017, pp.418–434. [13] VK Srivastava,Acousto - Ultrasonic Evaluation of Interface Bond Strength of Coated Glass Fibre – Reinforced Epoxy Resin Composites, Composite Structures, 30, 1995,pp.281 – 285. [14] SM Moon, K L Jerinaand H T Hahn,Acousto Ultrasonic Wave Propagation in Composite Laminates, Springer US, 1988, PP: 111 – 125. [15] Oh-Yang Kwon andSeung-Hwan Lee,Acoustoultrasonic evaluation of adhesively bonded CFRP-aluminum joints, NDT&E International, 32, 1999,pp.153–160. [16] Anil Tiwari, Edmund G, Henneke II and John C Duke,Acousto-ultrasonic (AU) Technique for Assuring Adhesive Bond Quality, The Journal of Adhesion, Vol. 34, 1991, pp. 1-15. [17] Alex Vary, The acousto-ultrasonic approach, NASA Technical Memorandum 89843, July 12-15, 1987 [18] I M Daniel, J JLuo, H M Hsiao,Acousto-ultrasonic techniques for evaluation of bond integrity of composite repair patches, Review of progress in quantitative non-destructive evaluation, Vol. 17, 1998, pp. 1331-1338. June 2019
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Ultrasonic NDE of Large Composite Structures in Defense Applications for Fabrication Defect Identification with Quality Image Presentation Avinash Hood*, C Ramdas, Irfan Khan, Monali Pawar, and Makarand Joshi Composite Research Center, R & D E (E), Dighi, Pune-411 015, INDIA Email : *ahood@rde.drdo.in Contact :02027044865
ABSTRACT Composite structures are nding wide applications in the areas of defense due to their characteristics of high specic strength and high specic modulus. These structures are manufactured using one of the cost effective fabrication techniques, known as Vacuum Assisted Resin Transfer Molding (VARTM). In the present work fabrication defects such as dry region / low saturation region, commonly occurring in the structure manufactured using VARTM, have been identied using ultrasonic A-scan testing. A suitable size of grid is marked on a structure on which scanning is to be undertaken, Ascan are acquired in a systematic manner at all these grid locations in pulse echo mode. Final results in the form of C-scan amplitude image and C-scan thickness image are presented by processing the acquired A-scan signals through in-housed developed algorithm in Matlab platform. A novel way of representing A-scan data as a quality image is presented in the paper. These GFRP/CFRP structures manufactured with epoxy as matrix shows excellent ultrasonic amplitude variation with different resin saturation levels in the structures. By measuring the ultrasonic signals at pristine stage, at different resin saturation levels, and testing the samples destructively under mechanical loads, correlation between mechanical characteristics and ultrasonic amplitude has been established. Keywords: NDE of composites, ultrasonic testing, sonar dome, quality image. 1.0
C
INTRODUCTION
omposite structures made of Carbon Fibre Reinforced Plastics (CFRP) / Glass Fibre Reinforced Plastics (GFRP) and polymer-based epoxy have high strength and stiffness while being light weight[1]. Because of these attractive features, composites are widely used for structural applications in defense applications such as sonar dome, armored hull of ICV, mobile heli-portable bridges etc. There are number of fabrication methods to realize the large composite structures. One of the promising techniques for realization is, out of autoclave manufacturing technique, Vacuum Assisted Resin Transfer Molding (VARTM).Due to the complexity of shape and size of the structures, often there is difficulty for resin infusion at critical locations. Inspite of best technical efforts, practically there remain certain regions in the fabricated structures with resin rich areas and resin starved areas. These regions need to be identified through suitable non- destructive testing methods [2]. Ultrasonic signals shows good sensitivities to different resin saturation levels in the fabricated structure[3]. As the defense structures such as sonar dome, bridges are large in size, ultrasonic testing using automated gantry system still remains a challenging task. In addition, there is a variation in thickness and geometry in each structure which makes interpretation of NDE results complex. Wronkowicz A et al [4], used pulse echo and phased arrayed method for ultrasonic testing. Paterson et al [5] used immersion through transmission technique to evaluate elastic constants of composite material. Caminero et al [6], utilizes phased array ultrasonic method to identify and evaluate manufacturing defects in composite laminate. In the present paper, a methodology for inspection and testing of VARTM fabricated large composite structures using ultrasonic A-scan acquisition is presented. June 2019
As a case study, testing results for indigenously developed sonar dome and CFRP bridge section is presented. Result representation as a simple quality image by combining information from amplitude C-scan and thickness C-scan is proposed. In addition, procedure for qualitative resin saturation evaluation with ultrasonic testing, calibration with mechanical destructive test for future use is also presented. The organization of this paper is as follows. Section two provides details about sonar dome structure with test layout for inside and outside scanning. Section three provides detailed description about ultrasonic NDE test along with description for Graphical User Interfaced (GUI) based program designed for data acquisition, analysis and presentation of ultrasonic test results. Section four summarizes results of Ascan testing of dome from both inside and outside, quality image representation and description of A-scan testing with composite samples with different resin saturation levels and calibration with mechanical test results. Section ve is conclusion, which deals with observations for large composite structure NDE scanning. 2.0 COMPOSITE STRUCTURES IN DEFENCE APPLICATION Large number of structural applications for defense systems today is being realized in Fiber Reinforced Plastics (FRP) based composites. For some applications it is mandatory to use FRP based composite for the given end requirement. These structures can be realized as single co-cured product with all structural complexities. Hence a single composite structure from inspection point of view may have different sections with different composition and/or thickness. This section summarizes two defense products which are considered as case studies for NDE inspection in this paper. www.isnt.in
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2.1 COMPOSITE SONAR DOME Composite sonar dome fabricated with VARTM process is as shown in gure 1. Overall the length of the dome is 10.5 m, width in the bulbous section is 3m and height is 3.1 m. It consists of different sections based on various technical requirements. Primarily it has acoustic window region, which is transparent to propagation of underwater sound (acoustic) waves. It is the most critical section of composite dome. Its construction is different compared to the other sections of the dome and is not monolithic. It has been constructed sandwiching rubber between GFRP face sheets. A-scan signals captured in this region are complicated due to sandwich multilayered construction [7]. Next one is aft region which accommodates the bafe wall. This section has been monolithic without rubber with tapering regions. Its thickness is as high as 40mm around certain region. Next is aft region which is situated at the end of the dome. It has monolithic construction with thickness in range of around 35-40mm with tapering sections. Top portion of dome is ange region which is around 60mm in thickness.
Figure 1: Composite sonar dome designed by R&DE
3.0 ULTRASONIC NDE TEST Ultrasonic testing is most popular NDE test for composite material owing to its suitability and exibility for complex shape inspection, high attenuation material inspection and so on[8]. For meaningful inspection all the parameters of hardware and software should be set to appropriate values. In this work ultrasonic testing in Pulse echo mode have been used in which single ultrasonic transducer is used as ultrasound transmitter and receiver. Data is recorded using National Instrument based USB digitizer unit which is controlled through application developed in Labview platform. This section summarizes all the hardware and software setting used to carry out ultrasonic Ascanning of test structure. 3.1 PARAMETER CONFIGURATION FOR TEST For the successful inspection using ultrasonic testing certain parameters are required to be estimated. In addition instrumentation setting for carrying out test plays important role. One of the parameter is velocity of ultrasound in the test structure at different regions, estimation of which is described in the next sub section. 3.1.1 Estimation of Ultrasound Velocity in Test Structure Estimation of velocity of the propagating ultrasound bulk wave in the test structure is required for analyzing the recorded Ascan signals. For this ultrasonic A-scan signal is acquired in the pulse echo mode at points on structure where physical measurement of thickness is possible. By noting down time of rst echo and multiple back wall echo, velocity of ultrasound at those points can be estimated by inputting known thickness as shown in gure 3. These estimated velocity is used as representative ultrasound velocity at these specic regions with assumption that it will remain same throughout region which is made of same material and having same thickness. These estimated velocities is used as input in the developed application to imaged manually acquired A-scan signals as ‘thickness C-scan’ signal in addition to ‘amplitude C-scan’ signal.
Amplitude in Volts
2.2 COMPOSITE 5M MOBILE BRIDGE Another defense product realizedthrough VARTM process is 5m composite bridge in CFRP with epoxy as resin base. One of the sections realized of composite 5m bridge is ramp section as shown in gure 2. It consists of different parts (Deck, Web, Flange) based on various technical requirements. As shown in gure-2, primarily it has a thick deck section varying from of 18 mm to 24 mm thickness. Basically, it is having 40-48 layers of carbon fabric having plies thickness of 0.45 mm, which gives nal thickness variation of 18 to 24 mm. Next section is Web, which is the intermediate wall for Deck & Flange sections. This section is having 32 layer of carbon fabric having layer thickness of 0.45 mm, which gives nal thickness variation of 14.5 to 16 mm.
It’s having radius pattern at contact region of deck and ange section. Last is ange section which is having 40-42 layer of carbon fabric having layer thickness of 0.45 mm, which gives nal thickness variation of 18 mm to 21mm. In gure 2 cross section image, all the dimensions mentioned are in mm.
Figure 2. 5m composite ramp section with cross section
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Figure 3. Ultrasound velocity estimation in test structure Time in sec
3.1.2 Instrumentation Parameter Setting Setting up various instrumentation for given test is important aspect of ultrasonic testing. Figure 4 shows instrumentation set up used for carrying out A-scanning of composite structures. Recorded signal to large extent depends upon the setting of Pulser receiver unit, digitizer unit through the software setting of the soft panel. Usually the standard sample specimen is required to congure all the instrumentation. June 2019
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If the structure has multiple interfaces, thickness tapering sections, sandwich construction etc., it requires standard calibration samples of each to be fabricated using same manufacturing process through which actual structure is realized. Input excitation along with other parameters of the Pulser receiver are set in such a way that maximum thickness back wall echo appears and it does not get saturated for low thickness section of the structure. Thus parameters are congured by visibly assessing healthy region of test structure with maximum output on receiver signal at low thickness region and measurable back wall signal at highest thickness of the test structure. If the test results are to be compared with some reference and/or structure, same parameters setting of the instrumentation need to be used for both the test. Any alteration of the instrumentation parameter leads to different test result. For the case study of sonar dome ultrasonic inspection, instruments, hardware and software parameters setting mentioned in table 1, 2 and 3 respectively are utilized. Sr No 1 2 3 4 5 6 7
Equipment used Remote console (Dell make Laptop) USB based NI digitizer NI 5133 Olympus make Pulser Receiver PR5058 Panametric 0.5 MHz transducer V101 Water sprayer along with water gel CFRP samples for calibration LabVIEW data acquisition program
Figure 5. Scanning layout for outside, inside of dome with cross section at acoustic window
Table 1: Summary of instruments used for test Parameter
Set Value
Parameter
Set Value
Channel
CH 1
Mode
Pulse echo
Voltage
400V
Gain
40 dB
Sampling Fequency Samples Trigger Filter used LP Filter HP Filter
100 MS/s 5000 CH 0 Low pass filter 1.5 MHZ 0.1 MHz
Velocity 2300 m/s Data saving Filter signal ON Table 2: Data acquisition Labview program
PR 5058
Attenuation 10 dB 10 dB Attenuation 1 dB
5 Db
Damping
100 Ohm
PRF
50 Hz
HP Filter
0.1 MHz
LP Filter
1.5 MHz
Table 3: Instrument PR5058 settings
NI 5133
V 101
F i g u r e 4 . Ultrasonic A-scan testing instrumentation
3.2 MEASUREMENT PROCEDURE As pulse echo mode is utilized for NDE inspection, data is acquired from both inside and outside of the dome.These structures should be marked with measurement points where data need to be acquired for manual C-scan construction post data acquisition. Next sub section provides details about scanning and measurement layout. June 2019
3.2.1 Scanning Layout Figure 5 shows dome marked with grid pattern from outside and inside along with cross section at acoustic window region of dome which is at front side of dome. As it is very large structure, systematic approach has been adopted to acquire ultrasonic A-scanning. Dome is divided broadly as LHS and RHS. Further grids of size 100 mm x 100 mm have been marked.
3.2.2 A-Scan Acquisition A-scan data is recorded in each of the grid in systematic manner. Grids are group as block with 9 x 9 grids each as row and column. Data is acquired in block wise fashion from left to right and top to bottom as shown in figure 6 which is one representative of complete scanning. For acquiring A-scan signals, water based gel is applied on the structure along with water sprayer. As these structures are vertically aligned and are at field locations, water gel helps in coupling ultrasonic energy to test structure.
Figure 6. Measurement pattern for outside scanning of RHS side of dome
3.3 A-SCAN SIGNAL POST PROCESSING AND ANALYSIS Data analysis and result representation after post processing the signal is essential for meaningful interpretation of acquired signals. As the collected A-scan signals are large in number, data interpretation and analysis is cumbersome and time consuming job for accessing recorded individual A-scans. Thus, for ease of data import, interpretation and nal representation of result, Matlab based application tool has been developed as shown in gure 7 and is used in the current work. In this application, all recorded signal can be imported by providing le path of the directory which is used to store these recorded A-scans during measurement. It provides A-scan analysis by providing tools such as Hilbert transform for enveloping the RF signals of A-scan for estimation of group velocity.
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in the recorded A-scan signals. Figure 9 shows results for inside scanned dome. In this case highest occurred back-wall echo have been imaged as per the requirement to measure highest thickness. Black color in the image shows saturation level indicating thickness more than 65mm. Due to resin over saturation in the bottom of the dome, these regions have high thickness as it is resin rich areas and subsequently very less ultrasonic amplitude is recorded at these locations as indicated by white color in displayed image in gure 9.
Figure 7. A-scan analysis application in Matlab
Different results based on selected parameters can be plotted. Recorded A-scan signal can be view as multiple representations. Also user can import data subsection wise and generate thickness image, back wall echo only image, multiple echoes image etc. Additionally there is provision to plot C-scan amplitude and thickness image by noting peak amplitude value and peak time value in selected window from acquired A-scan signals. Depending upon the requirement, suitable image representation can be displayed. 4.0 RESULTS OF ULTRASONIC A-SCANNING After post processing the recorded signals, it needs to be presented to the user in suitable form. Most commonly used representation is C-scan image presentation. However in the Cscan only the energy or amplitude information is presented to the user. In majority of the application it is also imperative to know about the thickness proling of the test structure. Hence by utilizing estimated ultrasonic wave velocity, time or depth information can be converted to and represented as thickness C-scan image. This section summarizes results of A-scan testing of sonar dome for inside and outside scanning. Results have been presented in different forms for thorough analysis with easy understanding. Mainly two images C-scan thickness plot and C-scan energy or amplitude plot has been presented in this section. Thickness plot can be displayedfor different echoes in acquired signals. Thus if there are three wave groups in the recorded A-scan we can get three different thickness C-scan images or we can plot thickness where highest peak has occurred in the recorded A-scan signal. In the next sub section later representation is displayed for sonar dome case. As a case study for concept of quality image, results for 5m composite bridge is discussed. 4.1 COMPOSITE SONAR DOME TEST RESULTS Figure 8 shows C-scan thickness and C-scan amplitude image from the A-scan acquired from outside of the dome. Both amplitude and thickness information is presented as color map. Thickness is displayed in millimeter (0-70 mm) and amplitude in volts (0-3V) units. There are certain regions marked by red circle in gure 8 which show more thickness than designed. Also around certain region marked by blue circle shows less thickness or early back-wall echo than designed thickness. White regions in the image represent those areas where either A-scan signals have not recorded or no back wall echo detected www.isnt.in
Figure 8. Cscan thickness and C-scan amplitude image for RHS of outside s c a n n e d dome Figure 9. Cscan thickness at highest back echo location and C - s c a n amplitude image for i n s i d e scanned dome
4.2 QUALITY IMAGE REPRESENTATION Interpretation of ultrasonic test result, C-scan image, is a complex task which requires knowledge of the structure under test as well as expertise in the signal processing domain to extract and image desirable feature. Majority of existing ultrasonic NDE testing system presents test results as energy attenuation image with image interpretation part to be judge by user for nal acceptance and/or rejection of tested part. Attenuation imaging particularly in pulse echo mode with contact testing is prone to errors as it is subjective to variability in couplant application, person performing the scanning and orientation of test job etc. Also, at the end, user (designer) expects results in the form of acceptance/rejection or go no-go situation. A new methodology is presented to enhance the reliability of the data interpretation process by utilizing test images of thickness C-scan image and amplitude C-scan image. Both of these representations are equally important from quality aspect of the test specimen. Hence ‘Quality image’ as single image outcome from the ultrasonic testis proposed by innovatively combining information from these two representations by appropriate weights. Figure 10 shows result for ramp deck section shown in gure 2 of 5m composite bridge with C-scan thickness and amplitude image. Figure 11 shows owchart to obtain quality image. Both thickness C-scan and amplitude C-scan images are rst normalized by designed structural thickness (ideal condition) and desirable ultrasonic amplitude (~3V in this case). Next these are combined with weight percentage of 60% for thickness C-scan image and 40% for amplitude C-scan image. As these are normalized images, it gives index from 0 to 1. Figure 12, part A, shows quality image for results shown in gure 9. June 2019
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level as indicated by ultrasonic signal amplitude and mechanical test output.
Amplitude (Volts) summation Bending Strength (KN)
8.01
Figure 10. C-scan thickness and C-scan amplitude image for ramp deck of 5m bridge Figure 13. Resin saturation calibration samples with result
Figure 11. Flowchart to obtain quality image
Further by selecting right threshold in quality index image, a novel representation in the form of simple self-descriptive image can be generated as shown in gure 11 part B. This leads to better understanding of test results by person not necessarily expertise in the subject eld. In the presented test result image, green color indicates excellent quality region, yellow color as acceptable quality with red region as non-acceptable as per the criteria and threshold (0.8) set.
5.0 CONCLUSIONS AND DISCUSSION In this paper work carried out to inspect large composite products by ultrasonic testing is highlighted. Every defense composite structure has unique inspection requirement based on the application. Two inspection results of sonar dome and 5m composite bridge sections have been discussed in detail. Importance of thickness C-scan imaging along with amplitude C-scan is emphasized. With appropriate interpretation of the test results, it provides valuable quality addition to the designer of the product. In case of sonar dome, ultrasonic inspection successfully detected resin rich regions and resin starved regions. Also certain regions with anomaly as per the test results are highlighted. Concept of quality image representation is proposed to ease and automate ultrasonic test result interpretation. It is matter of discussion regarding weight distribution to be used to arrive at quality image. Also, methodology for quality image threshold value nalization needs to be worked out by carrying out experiments at sample coupon level. Final decision regarding acceptance, rejection of part/region will be easy once right value threshold is xed for particular structure. Needless to say every inspection requirements are unique and it greatly assists to carry out inspection job with proper knowledge about the test structure in all aspects. ACKNOWLEDGEMENTS The authors would like to express their gratitude to Shri V VParlikar, Director R&DE (E), Shri A K Patel, Group Director ASG for all the encouragement and support to carry out this work. Also the help rendered by entire CRC team at all the stages is deeply acknowledged.
Figure 12. Quality image with threshold image
REFERENCES
4.3 RESIN SATURATION LEVEL AND MECHANICAL TEST CALIBRATION For quantitative analysis it is desirable to know resin saturation levels in the nished composite products. Resin saturation level has impact on the mechanical properties such as bearing strength, tensile and compressive strength of the material. Ultrasonic signals shows good sensitivity to different resin saturation levels in the composite structure. Hence by preparing the composite samples at coupon levels with different resin saturation and testing these samples as per ASTM standard for mechanical test, calibration data can be generated. Figure 13 shows sample result of calibration test for samples shown in the gure. Ultrasonic amplitude have been summed up to arrive at a single number for comparison. As can be seen from gure, correlation exists between saturation
1.Isaac M. Daniel, OriIshai, “Engineering mechanics of composite materials”, Oxford university press, 2010 2.Don E Bray and Roderic K. Stanley, “Non-destructive evaluation, A tool for design, manufacturing and service”, Mc-Graw Hill, New York, 1997 3.Lester W. Schmerr, “Fundamentals of ultrasonic non-destructive evaluation”, Plenum press, New York, 1998 4. WronkowiczA. ,Dragan, K., Lis, K., “Assessment of uncertainty in damage evaluation by ultrasonic testing of composite structures”, Composite Structures, 2018 5. Paterson, D.A.P, I Jomah, W., Windmill, J.F.C, “Elastic constant determination of unidirectional composite via ultrasonic bulk wave through transmission measurements”, Progress in Material Science, 2018 6. Caminero MA, Garcia-Moreno I, Rodriguez GP, Chacon JM, “Internal damage evaluation of composite structures using phased array ultrasonic technique, Impact damage assessment in CFRP and 3D printed reinforced composites”, Composites Part B, 2018 7.S.C.Ng, N. Ismail, Aidy Ali, BarkawiSahari, J.M. Yusuf, B.W. Chu,“Nondestructive inspection of multi layered composites using ultrasonic signal Processing”, Material science and engineering, 2011 8. www.ndt-ed.org
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CORRIGENDUM Due to a typing error in the March issue, Page 40, Events Section, the caption below Dr. R J Pardikar’s picture mentioned “Dr. B Venkatraman, IGCAR delivering maiden Dr. Baldev Raj Memorial Lecture” instead it should have read “Dr. R.J.Pardikar, delivering Presidential Address”. JNDE regrets the error. Dr. R.J. Pardikar, delivering Presidential Address
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Read Ahead: ISNT President’s ‘Address at NDE 2018’ in Events Section, Page 42.
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PRESIDENT ISNT’S ADDRESS AT THE NDE 2018, MUMBAI 19TH DECEMBER 2018 Honorable chief guest, Shri. S A Bharadwaj, chairman Atomic Energy Regulatory Board, Respected Mr. Arvind Modgil, president-Reliability center of excellence, Reliance industries Ltd, Dr. Paritosh Nanekar, Chairman NDE-2018, Dignitaries on the dais, Distinguished guests, eminent scientists and engineers, esteemed delegates, sponsors of the conference, ladies and gentlemen. Good morning to all of you and welcome to NDE-2018. Friends, we are living in times of unprecedented change. In the last few decades science and technology has unleashed waves of innovation transforming society and business. Technology is increasingly becoming part of our daily life. Connectivity and access to information has given a stronger voice to individuals and communities. Quality of life has vastly improved in the last few years. Yet, there is so much more to be done. The professional societies like ISNT have got a big role to play in improving the quality of life. ISNT’S Vision is to help create a safer world by promoting the profession and technologies of nondestructive testing. ISNT has already crossed many mile stones of innovative contribution to the realm of the technological advances and has been continuously striving hard to promote NDE Science and technology in the country through knowledge dissemination, training and certication. The ISNT mission is primarily educational and informational. Its inuence ows from the highly visible functions such as to develop professional excellence, to publish professional journals, to raise public awareness, to organize seminars and workshop, to promote interdisciplinary research and education etc. Through our work, we help to dene and set standards for professional elds and to promote high standards of quality. Cultivating an active and motivated membership base is essential to ensure the continued success of the Society. We attract and retain students and early career engineers and capture their energy, creativity and passion. Today, we are a strong force of over 5000 members spread over 18 chapters across the country. We have our own internationally recognized training and certication scheme. We are doing yeoman service to the industry by providing the skilled manpower in the eld of quality and NDT. Our guiding principle is such that we keep one foot into the future even as we remain rmly rooted in the present. Change and innovation go hand in hand. We believe that innovation must embrace not just products but also business processes. India is proactively adopting technology to fundamentally reshape the way we do business. India is leading the digital transformation with signicant investments in Automation, Robotics, and articial intelligence across the value chain. With India poised for sustained growth, the NDE Technology has a great role to play to enhance manufacturing quality, safety and productivity of critical engineering products. The performance driven world also demands that engineering products and systems extend the operational life limits with greater reliability, safety and efciency with lower carbon footprint to meet the challenges of competitiveness and sustainability.
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NDE Science and technology is the key enabling technology. The NDE is increasingly expanding to new frontiers. T h e modern NDE has been playing a vital Dr. R.J. Pardikar, delivering Presidential Address role in ensuring the manufacturing quality, structural integrity and safety of components in Nuclear, Aerospace, automobile, power, defense, petrochemical and other fabrication industries. NDE Techniques are deployed to qualify the materials for critical applications, to control manufacturing processes, lower production costs and maintain a uniform quality level. The importance of Nondestructive Testing (NDT) as a Quality Control / Quality Assurance tool in the industrial domain cannot be over-emphasized. With the rapid advancement in research and technology, the NDT eld is becoming larger and more sophisticated day by day. Innovative research in materials science and digital technology is paving the way for more and more new methods in NDT technology. Developments in Computers, microelectronics, sensors, array technologies, numerical modeling, software and data processing etc. are enabling highly sensitive detection, sizing and imaging of smaller aws. Developments in signal processing, image processing, image fusion, articial intelligence methods are playing a vital role in aw characterization. The NDE research community is continuously striving hard to improve the capability of inspection methods and reliability to detect critical aws at lower cost with minimum impact on the serviceability and life cycle of the test structure. In this fast-developing environment, it is essential that the engineers and scientists working in the eld of NDE are abreast with all latest advancements and share their research ndings with the NDE fraternity. NDE-2018 will offer a wonderful platform for all the stake holders of NDE. The NDE-2018 will provide an excellent forum for scientists, engineers and practitioners as well as end users to review the latest developments, identify needs and opportunities for further advances, exchange knowledge and experience with other well-known experts and to outline the milestone for further progress in this fascinating eld. I wish all the delegates, authors, speakers and exhibitors a very enriching experience and a meaningful stay for the next three days. R J PARDIKAR PRESIDENT-ISNT
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PERMANENT INVITEES 57. Shri G. Ramachandran
NATIONAL CERTIFICATION BOARD MEMBER'S LIST (NCB)
MEMBERS 11.Shri. Anil V. Jain 12.Shri. Anil Kumar Das 13.Shri. V Deepesh 14.Shri. Dharamveer Singh 15.Shri. Dipankar Goutham 16.Shri. R.G.Ganesan 17.Shri. Gopalakrishnan 18.Shri. S. Hari Krishna 19.Shri. G. Levin 20.Shri. V Manoharan 21.Shri. Mukesh Arora 22.Shri. C.K. Muktopadhyay 23.Smt. Navita Gupta 24.Shri. Bhausaheb K Pangare 25.Shri.Partha Pratim Brahma 26.Shri.Rajul R. Parikh 27.Shri.Ravibabu Mulaveesala 28.Shri.S.R. Ravindran 29.Shri.Sadasivan. N 30.Smt.Sangita Kapote 31.Shri.Shashidar Pallaki 32.Shri.S. Shendkar 33.Shri.S. Subramanian 34.Shri.Sunil Gophan 35.Shri.G. Surya Prakash 36.Smt. Umrani K.J 37.Shri.M.N.V. Viswanath
Shri V.R. Deenadayalu Shri K. Balaramamoorthy Shri Ramesh B. Parikh Shri A. Srinivasulu Shri Dr. Baldev Raj Shri S. I. Sanklecha Shri Shri D.M.Mehta Shri K. Viswanathan Shri Dilip P. Takbhate Shri K. Thambithurai Dr. P. Kalyanasundaram Shri. V.Pari
1. 2. 3. 4. 5.
Dr. M.T. Shyamsunder Shri P.P. Nanekar Shri T. Loganathan Shri S. Viswanathan Shri B. K. Shah
REGIONAL CONTROLLER OF EXAMS 6. Shri S.K. Bandyopadhyay 7. Shri S.R. Ravindran 8. Shri Jayaprakash Hiremath
9.
PATRON Shri K. Balaramamoorthy
10 11. 12. 13. 14. 15. 16. 17.
MEMBERS Shri. R.B. Bhardwaj Shri V. Manoharan Shri Avinash U. Sonuwane Shri R. Sundar Shri Phani Babu Shri Dilip Gatti Shri ME. K.A Nerurkar Shri Bikash Ghose
18. 19. 20. 21. 22. 23. 24.
Shri Chintamani Khade Shri G.V.S. Hemantha Rao Shri. Uday B Kale Shri Sadasivan. N Shri. Vikas Neeraj Smt. Navita Gupta Shri M. Venkata Reddy
EX-OFFICIO MEMBERS 25. Shri R.J.Pardikar 26. Dr. B. Venkatraman 27. Shri Diwakar D. Joshi 28. Dr. Krishnan Balasubramaniam 29. Shri. Jaiteeth Joshi 30. Shri. P. Mohan 31. Shri Nerurkar K.A 32. Shri. V. Pari CHAPTER REPRESENTATION 33. Shri Hemant Madhukar 34. Dr. Krishnan Balasubramaniam 35. Shri M. S. Shendkar 36. Shri G.V.S. Hemantha Rao
June 2019
ANNOUNCEMENT
46
ANNOUNCEMENT
ISNT MEMBERS goes online... After a long wait, continued persuasion and with the vision of earlier Presidents of ISNT and the current president Dr R J Pardikar, nally, ISNT has launched the ISNT's Online Membership Module (iSOM) and also integrated it to the new website of ISNT www.isnt.in. The link for the membership area is http://isnt.in/member-area/. The link to the member area is also provided at the home page in the form of a button as shown below. Further details about the module and the functionalities are mentioned in the form of FAQ (Frequently Asked Question) and is available under the same link. Few of the important functionalities and features of the new membership module are as follows:Existing Member can now check whether their membership data is available online. Existing member can now check whether the e-mail ID is registered / updated online so as to get updated information from ISNT time to time and also would enable them “to nominate new member” to ISNT. · After registering the e-mail IDs to the online database, the members can generate password which will be sent to their registered e-mail IDs. · The existing members can now login to the membership area with the generated password and change the contact details and other elds by their own. · Members can now easily claim the membership discount offered by ISNT for various events / programmes conducted throughout the countries through various chapters. · Prospective new member can now apply for new membership online through website under various categories like "Associate Membership", Student Membership", "Life Membership" etc. · After getting the conrmation by the nominating members and paying the membership fees, the membership will be accepted and the Membership certicate will be generated online and the same will be sent automatically to the registered e-mail ID. · The password to login to the member area can be generated immediately for the new registered members after receiving the membership certicate. · ·
For more details please go through the FAQ available at the link as mentioned above. Please use the contact form available at link http://isnt.in/contact/ to contact us or write to us at info@isnt.in / isntheadofce@gmail.com for any query. Bikash Ghose Hon. Jt Secretary, ISNT
June 2019
www.isnt.in
47
NDT Course Calendar for 2019 - 2020 by ISNT CHENNAI SR. NO
MONTH
1.
July
VT -1905
2.
August
3.
August
4.
COURSE CODE
TRAINING PERIOD FROM
TO
EXAM DATE
Visual Testing Level- II
22.07.19
25.07.19
27.07.19
ST -1906
Surface NDT Level II (MT & PT)
01.08.19
07.08.19
RT -1907
Radiographic Testing Level II
21.08.19
28.08.19
Ultrasonic Testing Level II
11.09.19
18.09.19
September UT -1908
COURSES
*COURSE LAST DATE TO RECEIVE FEES APPL FORM Rs. 6,000/-
17.07.19
09.08.19 & 10.08.19
10,500/-
25.07.19
30.08.19 & 31.08.19
12,000/-
16.08.19
12,000/-
05.09.19
20,000/-
10.10.19
10,500/-
01.11.19
7,000/-
19.11.19
12,000/-
04.12.19
6,000/-
02.01.20
20.09.19 & 21.09.19 25.10.19 & 26.10.19
5.
October
ET -1909
Eddy Current Testing Level -II
16.10.19
23.10.19
6.
November
ST -1910
Surface NDT Level II (MT & PT)
07.11.19
13.11.19
15.11.19 & 16.11.19
7.
November
RI -1911
RT Film Interpretation II
25.11.19
28.11.19
30.11.19
8.
December
UT -1912
Ultrasonic Testing Level II
11.12.19
18.12.19
20.12.19 & 21.12.19
9.
January
VT -1913
Visual Testing Level- II
06.01.20
09.01.20
11.01.20
10.
February
RT -1914
Radiographic Testing Level II
30.01.20
05.02.20
07.02.20 & 08.02.20
12,000/-
24.01.20
11.
February
UT -1915
Ultrasonic Testing Level II
19.02.20
26.02.20
28.02.20 & 29.02.20
12,000/-
15.02.20
*GST 18% APPLICABLE FOR COURSE AND EXAMINATION FEES.
Important Note: All courses, examinations and Certications are based on IS 13805. If any one wishes to write Examination as per SNT TC 1A. The employer shall have / develop a written Practice based on “SNT TC 1A”.
R.Vivek (Hon. Secretary) ISNT Chennai Chapter Module No.59, 3rd Floor, Readymade Garment Complex, SIDCO Industrial Estate, Guindy, Chennai - 600 032 Tel.: No. 044-45532115 Email: isntchennaichapter@gmail.com
BUSINESS CARD ADS
www.isnt.in
To advertise for Business Card size ads in JNDE, please contact:Rachna Jhaveri : 022 61503839 or email to isnt.jnde@gmail.com
June 2019