Experimental Evaluation of Strength Degradation Temperature for Carbon Epoxy Filament Wound Composite

Polymeric composites have been widely used in various structural and thermal aerospace applications (Rajak et al., 2019). Polymeric composites having high strength and high modulus reinforcement are ideally suited for lot of critical aerospace applications as structure is designed with high specific strength and high specific modulus (Muralidhara et al., 2020). In case of launch vehicles/ missiles, one such application is design and manufacturing of solid rocket motor casing with polymeric composites as it gives high performance and reduces inert weight of propulsion system. The high specific strength and high specific modulus of composite materials makes it ideal choice for designing the composite rocket motor case (CRMC). Mostly the CRMCs are designed with high strength and high modulus carbon fiber as reinforcement and Epoxy Resin as matrix (Sharma et al., 2020). These are manufactured with filament winding process. As per ASTM D 2290 test method, the apparent tensile strength can be evaluated by preparing ring specimens from filament wound shell which simulates the hoop winding and cylindrical geometry of composite motor case. Composite rocket motor casings are designed with optimum margin of safety to meet requirement of high internal pressure due to combustion of solid propellant. Solid rocket motors are designed with insulation system for internal surface to limit back wall temperature of casing with in design specification depending on casing material (Trudeau, 1990). However, during flight in trajectory, the temperature on external surface of rocket motor will rise due to kinetic heating as result of aerodynamic drag. In case of rocket motor casings made up of polymeric composites, this temperature rise on external surface is more critical than metallic casings. The mechanical properties of FRP composites degrades beyond certain temperature, depending primarily upon resin system and its glass transition temperature (Tg). In present work, the method of ring fabrication using filament winding is used to prepare test samples to experimentally test and evaluate apparent tensile strength with temperature of Carbon Epoxy composite. The tensile test at ambient is also done on specimens made from carbon Epoxy laminate using filament winding technique and are compared with ring test results to establish correlation. The Glass Transition temperature (Tg) for Carbon Epoxy is also determined with Dry Scanning Calorimetry (DSC) technique. © 2020. All Rights Reserved.