Multiscale thermo-mechanical analysis of cure-induced deformation in composite laminates using Direct FE2

In this study, we propose a versatile two-scale approach for thermo-viscoelastic analysis of the curing of composite laminates. Cure-induced residual stresses and part distortion significantly affect the quality and assembly of composite parts. An accurate computational tool for process optimization is required to replace time consuming and expensive experimental trial and error. The proposed method accounts for the different behaviors of fiber and resin during the curing process in terms of heat transfer and mechanical deformation. In particular, the evolved resin properties are described by a cure kinetics model and a cure-dependent viscoelastic constitutive model, which can be characterized directly from experiments. These microscopic mechanisms are concurrently used to reproduce the induced macro deformation. By virtue of the Direct FE2 implementation, the two-scale modeling only requires a single finite element analysis, where the macro laminate and the micro RVEs are coupled through multi-point constraints. Finally, this approach was employed to predict process-induced distortions of flat and curved composite parts subject to a typical two-dwell cure cycle. The results are verified by direct numerical simulations and typical residual deformations such as warpage and spring-in are well captured.