Microscale viscoplastic analysis of unidirectional CFRP composites under the influence of curing process

Cure-induced residual stresses have a great impact on the mechanical behavior of carbon fiber reinforced polymer (CFRP) composites. This paper develops an integrated analytical framework to study the effect of the cure-induced residual stresses on the mechanical behavior of unidirectional IM7/8552 composites. During the curing process, evolution of the material properties of the resin matrix is captured using the cure hardening instantaneous linear elastic (CHILE) model. In addition to the mechanical strain, thermal and chemical shrinkage strains of the resin are taken into account in the determination of the residual stresses. By introduction of the predicted residual stresses into the representative volume element (RVE), the quasi-static and dynamic compression analyses are performed to demonstrate the local viscoplastic deformation of the matrix and the homogenized stress–strain response of the composites. Simulation results are in good agreement with the experimental data. The comparative analysis indicates that the cure-induced residual stresses lead to an earlier nonlinearity and lower compressive strength. Furthermore, to investigate the effect of the fiber distribution on the residual stresses and compressive response of the composites, a parametric analysis is performed, in which two parameters are considered, i.e., minimal inter-fiber distance and fiber volume fraction.