Influence of Temperature Dependent Matrix Plasticity on the Formation of Residual Stresses and Initial Matrix Failure in CF/Epoxy

摘要

The formation of process induced residual stresses in CF/Epoxy was investigated by finite element methods at the micromechanical level. Based on results from thermomechanical experiments, the temperature dependent nonlinear matrix behavior was implemented into the FE-calculation. Different macroscopic boundary conditions, like a free or constrained UD-laminate, a cross ply laminate or a laminate, which is subjected to a temperature gradient, have been considered. The results showed that biaxial or triaxial stresses are generated after cooling down depending on the boundary conditions. It is found that for some boundary conditions the residual stresses are reduced by matrix plasticity and no initial matrix failure occurred while other boundary conditions cause a stress state which leads to matrix failure without yielding, in consequence of the used yield and failure criteria.