Cure-Cycle Simulations of Composites With Temperature- And Cure-Dependent Anisotropic Viscoelastic Properties and Stochastic Delaminations

Complete three-dimensional, anisotropic, nonhomogeneous degree of cure, temperature-and time-dependent nonlinear thermal properties, and linear viscoelastic constitutive relations are formulated to describe composites during curing processes in autoclaves. Specific temperature, degree of cure, and stress profiles are determined for two distinct fiber orientations and two thicknesses by time-dependent finite-element analyses. Expressions for the probability of times to delaminate during cure under combined stresses are derived. Delami-nation onset survival times of laminated composites in the autoclave during manufacture are investigated in detail, and their dependence on temperature and thickness is shown. Specific areas are identified where critically needed deterministic and stochastic experimental data for thermal, viscoelastic, and failure properties during manufacturing cycles are unavailable.