Flexural Behavior of Cross-Ply Thermally Aged Bismaleimide Composites

Thermal aging in oxidative environments is a critical degradation mechanism for polymer composites in aerospace applications. After degradation, the composite strength is reduced and the working life is shortened. In the present work, thermal-oxidation effects on the bending behavior were studied experimentally and numerically. A cross-ply laminate was manufactured using, IM7G/AR4550, a unidirectional bismaleimide prepreg system. Thermal aging experiments were conducted in air at 176.7 °C (350 °F) for 1,700 hours. Weight loss of the samples was monitored during aging and three-point bending test was performed to characterize thermal oxidation impact on the bending behavior. 3D transient coupled diffusion-reaction simulations were conducted based on representative volume elements (RVE) using COMSOL Multiphysics. Three-point bending test was simulated using ABAQUS taking the effect of the transient oxidation growth and degradation into consideration. Thermal aging for 1,700 hours resulted in a weight loss of 0.5 % and a reduction of 19 % in the flexural modulus of the samples. Weight loss and flexural modulus simulation results showed a good match with the experimental findings.