Microstructure Image-Based Thermo-Mechanical Damage of Aged Bismaleimide Composites

Thermo-mechanical behavior of high-temperature polymer matrix composites is determined by thermal transport and mechanical properties, and their respective evolution. Chemical aging mechanisms, namely thermo-oxidation dominates the property degradation and the service life reduction of high temperature composites. In this work, thermal transport properties are characterized for virgin and thermally aged carbon/bismaleimide test coupons using laser flash and differential scanning calorimetry. Numerical models are built for the temperature and oxidation state dependence of the thermo-physical properties. These models are used to simulate thermo-mechanical damage of a thermally oxidized laminate under steady heat transfer conditions. Object-oriented finite element is utilized to build a microstructure-based domain for the simulation. The developed simulations include the evolution of the elastic properties, coefficient of thermal expansion and density. The induced thermal residual stresses are investigated for failure initiation. The numerical and experimental outcomes will aid in better understanding of the specific contribution of residual stresses in the spontaneous cracking of aged composites