New Product Development approach for design and FEA analysis of Skid Plates - A Case study

IJSRD - International Journal for Scientific Research & Development| Vol. 4, Issue 03, 2016 | ISSN (online): 2321-0613

New Product Development Approach for Design and FEA Analysis of Skid Plates – A Case Study Jayaraju S H1 Dr. N S Narahari2 1 Student 2Professor and Head 1 Department of Mechanical Engineering 2Department of Industrial Engineering & Management 1,2 RVCE, Bengaluru Abstract— Vehicle safety is an important factor during design and development of any automobile. There are several components which make an automobile and each component has its own functionality and importance. In the same way there are many accessories which are required to be used along with the vehicle. One such accessory is skid plate which is very much essential for off-road vehicles. In this paper, a NPD approach is used to develop a skid plate for safeguarding the propeller shaft. To design and develop skid plate, a survey has been carried out to know the necessity of skid plate. From concept generation and selection, 2 feasible concepts were selected for FEA and static structural analysis has been carried out for UDL of 1400lbf and then for various loading conditions. From comparison of results, a feasible concept is recommended for prototyping.

Key words: Skid Plate, FEA (Finite Element Analysis), NPD (New Product Development), Von-Mises Stress, Deformation, PLC (Product Life Cycle) I. INTRODUCTION Propeller shaft is a critical part in vehicles. Especially in Four Wheel Drive vehicles they may be fractured due to impact loads from the uneven terrains. Hence safeguarding the propeller shaft is the area of focus. Skid plates are made up of tough materials fitted to vehicle’s underbody to protect the parts from damage. Hence there are many key factors which plays crucial role in designing the skid plate that includes DFM (Design for manufacturing), DFA (Design for environment) and cost optimization. Skid plates are usually aftermarket modification for customers who prefer more safety and long life of their vehicle. Skid plates are made using different materials. This includes aluminum alloys, structural steel, plastic and many more. The material to be chosen depends on material’s cost and toughness. As the weight of skid plate increases the fuel efficiency decreases but provides protection even in the extreme conditions.

Light weight skid plates do not affect much on vehicles weight and hence maintain its efficiency.

A survey has been made which explains the design, development and analysis of automobile components. Some of them are cited herein.

Riley D and Jones R [1] explained the increasing adoption of underbody shields as a means to withstand high levels of impact and abrasion from small stones and gravels, but also they need to be light weight. They described the development and validating the underbody components using 100% polypropylene and self-reinforced composites and concluded that the material has high levels of impact resistance even in the low temperatures.

Ying-Kui Gu et al. [2] said that the product life cycle (PLC) is a continuous process. It’s the product development stage that plays a crucial role in a product’s

performance during the entire PLC. The scope of PLC is to improve the product quality, reduce development cost and shorten development time.

Chan S L [3] described that to become successful in dynamic business environment, companies usually target on improving their new product development (NPD) by identifying customer needs and improving product quality.

Automobile safety is a hierarchical process and a little variation in the final part/product leads to variation in all assembly parts, tools etc. Modeling of variation propagation is essential in predicting the product dimensional quality. In this research sheet metal part is assumed as a rigid body and finite element analysis (FEA) is usually used to analyze the flexible deformations (10) II. CONCEPT GENERATION In the concept generation stage the needs and drivers which serve the need are listed. T.Taura et al. [4] defined concept generation as the process of choosing a desirable concept towards the future. Concept generation is done by design creativity which has two stages: planning for something and concept creation. The second phase is called as the concept design. Joanna Tsenn et al. [5] proposed that design always starts with concept generation for a known problem. It involves exploring various potential solutions before choosing a best concept that fulfills their requirements. The concept generation using conceptual design is the first stage of design in a systematic approach. The customer requirements for the skid plate were identified through a survey and the corresponding drivers to meet those needs were listed as shown in table I of appendix. The basic requirements for concept generation is done using attribute listing technique as shown in table II of appendix and these attribute were combined in the concept combination table as shown in table III of appendix.

A. Concept 1

Fig. 1: Concept 1

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New Product Development Approach for Design and FEA Analysis of Skid Plates – A Case Study (IJSRD/Vol. 4/Issue 03/2016/551)

B. Concept 2

Fig. 2: Concept 2 C. Concept 3 Fig. 4: Concept 1

Fig. 3: Concept 3 III. CONCEPT SELECTION Concept selection is a technique of choosing the best concept which satisfies the product design specifications.

Kevin Otto and Katja Otto [6] proposed a multi criteria assessment tool for screening preliminary product platform concepts. They generated a list based on the personal expertise of platform development. Each metric was rated onto a scale from 0 to 10 and then combining the metric score using a simple weighted sum. The concept selection is done on the basis of customers needs by taking one of the products as reference or by assuming the requirement. Then the concepts are rated with respect to requirement and then they are ranked and top two ranked concepts are selected for further development.

Concept scoring is a technique of concept selection where the concepts are rated from 1 to 5 based on their relative performance. 1-much worse than requirement, 2worse than requirement, 3- same as requirement, 4- better than requirement, 5-much better than requirement.

Using concept scoring technique as shown in table IV of appendix, it was found that among 3 concepts, concept 1 and concept 2 are top scored concepts and hence they are used in further steps.

IV. CONCEPT EVALUATION Concept evaluation is an important step in the product development process as it shows the overall capability of design against design objectives.

Following steps involved in concept evaluation: A. Importing the Model The skid plate models are built using NX 7.5 and imported to ANSYS Workbench 17.0 and they are as shown in figure 4 and 5.

Fig. 5: Concept 2 B. Defining the Material Properties The material of the skid plate is 1018 Carbon structural steel with Young’s modulus (E) 2e6psi, Poisson’s ratio 0.3, Yield tensile strength 39900psi.

C. Meshing Mesh generation is a technique of dividing the given body into sub regions called elements. Initially coarse meshing is done to reduce the computation time. Further the mesh is refined to tetrahedron meshing. Tetrahedron mesh consists of small sized triangle which gives the number of nodes and elements present. C. Veyhl et al. [7] explained the meshdependence of structural nonlinear finite element analysis (FEA). Various meshes like tetrahedron, hexahedron and mixed were taken into consideration. It was concluded from the obtained results that linear mixed meshes were superior than linear- and quadratic tetrahedron and linear hexahedron.

D. Defining the Boundary Conditions The boundary conditions are defined on the components.

Preliminarily, a UDL of 1400lbf is applied on the skid plate and fixing the end supports on both sides as shown in fig 6 and 9. The total deformation and von-mises stress (equivalent stress) are considered.

E. Solve the Model The model was solved using the solver which is present in the software ANSYS 17. It calculates equivalent stress and deformations for each element to obtain the total deformation and equivalent stress results.

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New Product Development Approach for Design and FEA Analysis of Skid Plates – A Case Study (IJSRD/Vol. 4/Issue 03/2016/551)

1) Result Analysis for UDL of 1400lbf on Concept 1 Once the model was solved, the results of von-mises stresses and deformations were plotted as shown in figure 7 and 8.

The results plotted were indicated by different color bands.

Fig. 9: Boundary conditions on Concept 2

Fig. 6: Boundary conditions on Concept 1

Fig. 10: Deformation for load of 1400lbf

Fig. 7: Deformation for load of 1400lbf

Fig. 8: Stress induced for load of 1400lbf 2) Result Analysis for UDL of 1400lbf on Concept 2 Once the model was solved, the results of von-mises stresses and deformations were plotted as shown in figure 10 and 11.

The results plotted were indicated by different color bands.

Fig. 11: Stress induced for load of 1400lbf As shown in table V of appendix, For the UDL of 1400lbf on both concept 1 and 2, the deformation is negligible for both the concepts 1 and 2. The von mises stresses induced was 25012psi and 38618psi for concept 1 and 2 respectively which is less than yield tensile stress of 39900psi, Hence both the designs are safe and max deformation do not results in any damage to propeller shaft.

But one major drawback of concept 1 is that the expensive sheet metal welding for joining the tubes to the supports.

3) Result Analysis for Different Loading Conditions The analysis is done for 3 loading cases: 1400lbf, 2100lbf and 2800lbf. The loads are applied on extreme end supports and on the mid span. The results of deformation and von mises stress for all the 3 loading conditions are shown in the table VI and VII of appendix.

Concept 1: load on extreme end 1, end 2 and mid span. Force of 1400lbf, 2100lbf and 2800lbf is applied at end 1, end 2 and mid span as shown in figure 12.

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New Product Development Approach for Design and FEA Analysis of Skid Plates – A Case Study (IJSRD/Vol. 4/Issue 03/2016/551)

conditions. As per the aim of this research two different models of skid plate are evaluated for different impact loads.

From the analysis results it was found that concept – 2 has shown the good results compared to concept -1 under conditions.

In the future work, the concept – 2 model can further be improved by providing reinforcement to enhance the strength and critical regions where stress concentration is more can further be modified.

REFERENCES

Fig. 12: Different loading conditions applied on concept 1 Concept 2: load on extreme end 1, end 2 and mid span. Force of 1400lbf, 2100lbf and 2800lbf is applied at end 1, end 2 and mid span as shown in figure 13.

Fig. 13: Different loading conditions applied on concept 2 By comparison of values for concept 1 and 2 for various impact loads at various locations as shown in table 6 and 7, it can be concluded that: For concept 1 the von-mises stress are less than yield tensile for all the 3 loading conditions. The deformation is also negligible without damaging the propeller shaft. As the impact load increases above 1400lbf gradually permanent deformation takes place and results in failure of component. Hence, it can be concluded that U shaped profile skid plate can withstand impact loads upto 1400lbf.

4) Result Analysis of Final Concept – 2 for Different Materials In the previous section, the results were discussed when an UDL of 1400 lbf is applied and it was seen that concept 2 yielded better results.

The concept is tested for different materials since selection of material plays an important role in ease of manufacturing and cost reductions. The other materials tested are aluminum alloys 6110-T6; magnesium alloys EQ21A-T6 M18330. From the results as shown in table VIII of appendix, it was seen that carbon structural steel yielded better results than other materials. Also, aluminum and copper alloys are costlier than steel, hence structural steel is chosen for prototyping.

[1] Riley, D. and Jones, R., “The Development of Lightweight, Highly Impact Resistant Components for Automotive Underbody Applications,” SAE Technical Paper, 2003.

[2] Ying-Kui Gu and Hong-Zhong Haung, “An integrated product and process development model supporting entire life cycle,” The 8th international conference on computer supported cooperative work in design proceedings, pp. 558-562, 2003.

[3] Chan S L, “A dynamic decision support system to predict the value of customer for NPD,” Decision support systems, vol 52, pp. 178-188, 2005 [4] T. Taura and Y. Nagai, “Perspectives on concept generation and design creativity”, Concept generation for design creativity, pp. 9-20, 2013 [5] Joanna Tsenn et al, “The effects of time and incubation on design concept generation”, Design Studies Vol35, pp. 500-526, Sept 2014 [6] Kevin Otto and Katja Otto, “A multi criteria assessment tool for screening preliminary product platform concepts”, Journal of intelligent manufacturing, July 2007 [7] C. Veyhl et al. “Mesh dependence of non-linear mechanical finite element analysis”, Finite Elements in Analysis and Design 46, 2010, 371–378.

[8] John B Bowles et al, “An assessment of RPN Prioritization in a Failure mode effects and Criticality analysis”, proceedings of annual reliability and maintainability symposium, 2003, pp.380-386 [9] D. Natarajan –“Failure mode and effect analysis”, Reliable design of Electronic equipment, 2015.

VI. APPENDIX Sl no

NEEDS

DRIVERS

CTQC

1

Easy for installation

*Size of the component *Weight of the component

2

Economical

*Amount of material used

*design specifications *Design for min number of parts *Economy of material *Quality of material

3

Resistant to weather changes

V. CONCLUSION

4

Life span

In this paper, various protective covers of skid plate are designed and evaluated for different loads under different

5

Should be less weight

*Type of material used and physical and chemical properties *materials used *design consideration *simple design *providing holes on

*Non corrosive materials *coating *Material property *constant servicing and maintenance *Design specifications

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New Product Development Approach for Design and FEA Analysis of Skid Plates – A Case Study (IJSRD/Vol. 4/Issue 03/2016/551)

the plate 6.

Should be reliable

*product structure *error tolerant design *resilience

*fault tolerance *recoverability

Table 1: Needs, Drivers and Ctqc’s (Criticality to Quality Characteristics) FEATURES Materials used Assembly Manufacturing method Shape of plate

ATTRIBUTES Steel Fasteners Sheet metal operations Profile-1 (plate with tube support)

ALTERNATIVES Aluminum alloys Welding

Conce pt 1

Conce pt 2

PLATE MATE RIAL

ASSEM BLY

Steel

Weldin g

METHOD OF MANUFACT URING Sheet metal operations

SHA PE OF PLA TE Profi le-2

Steel

Weldin g

Sheet metal operations

Profi le-1

Conce pt 3

Steel

Fastener s

Sheet metal operations

Profi le-2

Conce pt 4

Alumin um alloys

Weldin g

Sheet metal operations

Profi le-2

Conce pt 5

Alumin um alloys

Weldin g

Sheet metal operations

Profi le-1

Conce pt 6

Steel

Fastener s

Sheet metal operations

Profi le-1

Conce pt 7

Alumin um alloys

Fastener s

Sheet metal operations

Profi le-2

Conce pt 8

Alumin um alloys

Fastener s

Sheet metal operations

Profi le-1

Conce pt 9

Steel

Fastener s

Sheet metal operations

Profi le-3

Conce pt 10

Alumin um alloys

Fastener s

Conce pt 12

Steel

Alumin um

Weldin g

Sheet metal operations

Profi le-3

Weldin g

Sheet metal operations

Profi le-3

place.

Non removab le assembl y, difficult y in mainten ance

alloys

Table 3: Concept Combination Table Profile-2 (U Shaped profile) Profile-3 (Convex pipe with tube support)

Table 2: Attribute Listing Technique CONC EPT

Conce pt 11

Sheet metal operations

Profi le-3

COMM ENTS Non removab le assembl y, difficult y in maintena nce.

Non removab le assembl y, difficult y in maintena nce. Not all aluminu m alloys are weldable and they are costly.

Suitable only for light loading since bending takes place.

Suitable only for light loading since bending takes

Selection criteria

Weig htage

Ease of handling Ease of manufacturing Estimated production cost Durability

Concept 1 R ati WS ng

Concept 2 Ra tin WS g

Concept 3 Rat ing

W S

10%

3

0.3

3

0.3

3

0.3

30%

2

0.6

4

1.2

1

0.3

20%

2

0.4

4

0.8

1

0.2

25%

3

0.75

4

1.0

3

0.7 5

2

0.3

3

2

0.3

Maintenance 15% cost Total score Rank Continue?

2.35 2 Yes

0.4 5 3.75 1 Yes

1.85 3 No

Table 4: Concept Scoring Matrix Concept

Deformation (inches)

Concept 1 Concept 2

5.46e-2 4.88e-2

Induced von-mises stress (psi) 25012 38618

Table 5: Results of Deformation and Stress for Udl of 1400 Lbf Loading area/value Deformation (inches) End 1 Von-mises stress (psi) End 2 Mid span

1400lbf

2100lbf

2800lbf

0.10466

0.15144

0.20311

72897

80821

93295

Deformation

5.305e-2

Stress induced Deformation Stress induced

45322 0.11881 48729

8.223e2

0.1031

78901 0.1737 74459

83610 0.23691 94314

Table 6: Results of Analysis for Concept 1 for Various Loading Loading area/value Deformation (inches) End 1 Von-mises stress (psi) End 2 Mid span

Deformation Stress induced Deformation Stress induced

1400lbf 5.865e-

2100lbf

2800lbf

2

9.4e-2

0.11686

36516

65557

83686

1.737e-

2.101e-

3

3

4.02e-3

4883.4 8.91e-2 37179

7378.5 0.13407 44937

10013 0.17849 72605

Table 7: Results of Analysis for Concept 2 for Various Loading Material Aluminum alloys Magnesium alloys Structural steel

Deformation (inches) 0.11840 0.18009 0.04784

Von-mises Stresses (psi) 91851 95436 70675

Table 8: Results of Analysis for Various Materials

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