Multiscale Modeling of Residual Stress Development in Continuous Fiber-Reinforced Unidirectional Thick Thermoset Composites

The primary objective of this research is to develop a multiscale simulation framework to arrive at more realistic estimates of cure-induced residual stresses in the vicinity of the fiber-matrix interface in thick thermoset composites. The methodology involves simulations at the part level—employing homogenized rendering of the composite using micromechanics approach—within a finite element framework to obtain part-level temperature and degree-of-cure gradients and strains, and imposition of this information as boundary conditions at the mesoscale simulations, employing microstructural representative volume elements (RVE). A simple implementation of the multiscale framework, involving simulations at the part as well as the RVE levels, is demonstrated in the context of a thick, unidirectional continuous-glass-fiber-reinforced thermoset composite. The trends in the mesoscale residual stresses estimated by employing different RVE-level thermal and thermomechanical boundary conditions—displaying different degrees of coupling between the global and part-level simulations—are then examined. Significant differences are observed in the estimates of mesolevel cure-induced residual stress evolution obtained from simulations with a conventional symmetric RVE and those obtained by employing the multiscale approach involving detailed boundary conditions that realistically account for global thermal and mechanical strain histories