Multiscale modeling of failure behaviors in carbon fiber-reinforced polymer composites

In this chapter, we discuss a bottom-up multiscale modeling approach that effectively investigates the failure behaviors of carbon fiber-reinforced polymer (CFRP) composites by integrating low-scale structural and mechanical attributes. Computational models of four length scales are constructed and integrated to characterize CFRP composites with complex structures. Specifically, the mechanical properties of the nanoscale fiber/matrix interphase region are determined by molecular dynamics simulation results and an analytical gradient model. The interphase region is then incorporated into microscale representative volume element (RVE) models to characterize the failure strength and envelopes of unidirectional CFRP composites. These results are leveraged to propose an elastic-plastic-damage constitutive law for the fiber tows in woven composites, which more efficiently describes the mechanical response of mesoscale structural elements. Then, the failure mechanisms and failure strength of woven composites are effectively predicted and studied by mesoscale RVE models. Finally, building upon the models and results from lower scales, a homogenized macroscale model is shown to capture the mechanical performance of a U-shaped part under four-point bending. Along with the model integration, we also show that computational results are in good agreement with experiments conducted at different scales.