The composite industry is rapidly growing its applications of lightweight polymer matrix composites (PMC) in aircraft, industrial machines, and automobiles due to their increased fuel efficiency. The mechanical behaviors of PMCs are usually studied at room temperature rather than higher temperature because they are more economical to test. However, there are a lot of higher temperature applications such as high-powered rocketry and robotic industrial components. Rocketry demands to further decrease the mass of the rocket while maintaining stiffness, and motor actuators need to move quickly with low inertial components to increase manufacturing productivity.
This study uses empirical techniques to test and evaluate the mechanical properties of carbon fiber-reinforced composite at room and elevated temperature levels. The high resin epoxy pre-impregnated carbon fabric with a tow size of 3k and woven in a 2x2 twill weave was cured into laminated plates following an eight-hour cure profile, and waterjet cut to ASTM test samples. The tensile strength, compression strength, flexural strength, and stiffness were measured following ASTM standards D638, D6641, and D7264. The ASTM standard tests were conducted with the MTS 810 Universal Testing Machine at five temperature levels from 75 to 600 Fahrenheit. Additionally, hardness and impact resistance were measured following ASTM D785 and D6110.
It is expected that the tensile and compression strength will decrease slightly, while the flexural strength and hardness decrease dramatically, and impact resistance increase slightly. These changes will be observed as temperature levels are increased up to and past the glass transition temperature (362 Fahrenheit) of the neat epoxy resin. These measured values can be used to predict the strength, stiffness, impact resistance, and hardness of the material at any temperature between 75 and 600 degrees Fahrenheit. The experimental results and models can then be used for the design of composite structures in high-temperature applications.