CURING IN THICK COMPOSITE LAMINATES - EXPERIMENT AND SIMULATION

Thick part (>5 cm) temperature profiles were obtained from a one-dimensional experiment. These results are compared with the predictions of a computer simulation containing improved and existing models for extent of reaction, viscosity and other composite properties of the same resin/fiber system. In particular the simulation recovers the thermal behavior of a 5 cm thick, unidirectional Hercules AS-4/3501-6 graphite/epoxy composite laminate. Application of consolidation pressures based on predicted viscosities led to dramatic improvement in void content of a real laminate. The simulation is used to investigate important processing variables and changes in chemorheology and temperature in a thick section laminate during cure. The following results are found: initial extent of reaction is relatively unimportant; consolidation is important; the peak temperature originates near the surface of the laminate and propagates to the center; asymmetric temperature application changes the viscosity and cure profiles; viscosity never reaches low values simultaneously through the thickness in laminates in excess of 10 cm thickness.