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Cure Management for Bonded Composite Repair Wichita State University/NASA Human Exploration and Operation Mission Directorate

Bonded composite patch repairs are widely employed to repair flaws/damage resulting from manufacturing processes, fatigue, impact loading, etc., in metallic as well as composite structures. The repair process involves the removal of the flawed or damaged region from the parent structure, followed by surface preparation and bonding of the repair patch. The heat for curing the patch is typically applied using a

suited for field repair, the tight tolerances on the repair process often result in rejection of repairs and no mechanisms exist for mapping the temperature measurements to the mechanical properties of the adhesive bondline and the repair plies. In this program, several aspects of the repair process were investigated to integrate a ‘cure management system’ to control the repair process and assign a quality index to the repair patch. The activities were carried out as a multi-institution effort involving Wichita State University (WSU), Kansas State University (KSU) and University of Kansas (KU). A new cure management approach has been investigated and implemented for bonded composite repair in an effort to alleviate the risks associated with current repair practices and to improve the accuracy of post cure repair assessment.

Pictures and TTU C-scan image of failed test panel #1.

heating pad which is controlled based on feedback from one or more surface mounted thermocouples. The temperature measurements on the surface of the parent structure and/or the repair patch do not accurately represent the temperature prevailing at the bondline or interior plies. The relatively poor thermal conductivity of the uncured prepreg coupled with heat losses due to conduction through adjoining structure (e.g., parent laminate, core, frames, etc.), convection and radiation to the surrounding ambience, results in spatial variation of temperature within the repair patch and the adhesive layer. Therefore, the repair patch and adhesive bondline may be under-cured and could be detrimental to the performance of the repaired structure under service loading. In spite of the availability of out-of-autoclave prepreg materials which are

Dr. Bob Minaie and Dr. S. Keshavanarayana, Science PI’s, Wichita State University

Sarah Cox, NASA Technical Monitor, Kennedy Space Center, STMD

www.nasa.gov/epscor/stimuli

NASA EPSCoR Stimuli 2014-15

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EPSCoR Stimuli 2014-15  

NASA Office of Education’s Aerospace Research & Career Development (ARCD) is pleased to release NASA EPSCoR Stimuli, a collection of univers...

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