Thermoviscoelastic analysis of residual curing stresses and the influence of autoclave pressure on these stresses in carbon/epoxy laminates

The effects of autoclave curing pressure and cooling rate on the room-temperature curvature of carbon/epoxy [0degrees(1)/90degrees(2)] laminated strips have been examined. The whole study is performed without inducing any changes in the epoxy matrix degree of cure and glass transition temperature. A first set of laminates was cured according to the cure cycle recommended by the prepreg manufacturer in which only the cooling rates were changed. The results obtained show that modifying the cooling rate between industrially acceptable limits has no influence upon the shape of [0degrees(2)/90degrees(2)] laminated strips at room-temperature. The second set of laminates was also cured according to the cure cycle recommended by the manufacturer in which only the pressure path was modified. The results obtained show that the room-temperature curvature of [0degrees(2)/90degrees(2)] laminated strips seems to depend on the laminate initial in-plane dimension and is influenced by autoclave curing pressure. All the laminates manufactured are void-free and an analysis of fibre volume fraction has been performed. (C) 2002 Published by Elsevier Science Ltd.