Thermoviscoelastic Analysis of Residual Stresses and Warpage in Composite Laminates

Abstract

Linear thermoviscoelastic lamination theory was used to determine resid ual stresses and warpage in multidirectional woven-glass/epoxy laminates. The single "unidirectional" layer of the material was characterized by means of an accelerated proce dure. The material was assumed to be thermorheologically simple and the time-tempera ture superposition principle (TTSP) was used to obtain "master curves" for the viscoelastic properties. A numerical procedure was developed for determination of residual stresses and warp age, taking into consideration the irreversible polymerization shrinkage and boundary conditions during curing. Warpage was measured experimentally for [0 6 /90 6 ] and [0 11 /30] laminates using the projection moire method and results were in good agreement with the analytical prediction.