Investigation of residual stresses induced by composite forming using macro-micro simulation

As the thickness of a composite differs significantly from the size of a representative volume element, composite is studied at both micro- and macroscales. In this study, the synergy between the prescribed displacement boundary and massively parallel computing enables end users to model a composite described in the micro-meter scale and take into account the global influence of the forming process. After validating the software and material models, the residual stresses of a sandwich thermoplastic composite caused by the dynamic thermomechanical forming process were simulated. The results of the macro-micro simulation revealed that the micro structure of a composite consisting of continuous carbon fiber and thermoplastic that have significantly different material properties has a weak impact on temperature distribution throughout the thickness, but exerts a significant influence on the distribution of in-plane stresses. The stresses within a representative volume element at the top and bottom surfaces of the composite layer were further studied to explain the effect of the temperature gradient on the simulated stresses along with the axial and transverse directions of the fiber. The results of this study provide a practical method to reveal actual residual stresses feasibly and efficiently.