Evolution of curing residual stresses in composite using multi-scale method

Residual stresses occur in composite structures during curing process which play an important role in the deformation and mechanical properties of composite, especially for thick laminates. However, the experimental measurement of curing residual stresses is often costly and complicated. Alternatively, computational tools are used to predict the curing residual stresses. Considering the effect of multi-scale in composites, this paper proposes a multi-scale model to predict the residual stresses of composites during the curing process. At the part level, a macro-scale three-dimensional model, which incorporated the thermo-chemical model and residual stress model, is developed by considering the time-dependent properties of material performances during curing process. The two sub models are mathematically coupled to solve for the process with variables interactively to obtain part-level temperature, degree of cure gradients and macro curing residual stresses. At the reinforcement level, a representative volume elements (RVE) is employed to calculate the micro-scale residual stresses by using the results of macro-scale simulations. The results show there is a significant difference in the calculation of micro residual stresses by introducing the effect of multi-scale model. Subsequently, the effect of different boundary conditions and fiber arrangement are discussed.