Analysis of the Viscoelastic Response of Composite Laminates During Hygrothermal Exposure

The linear viscoelastic response of polymeric matrix laminated com posites to hygrothermal exposure is investigated within the framework of lamination theory. Experimentally measured curvature changes in non- symmetric GY70/339 composite laminates during long term exposures to elevated hygrothermal conditions are shown to be accurately predicted by the linear viscoelastic analysis. Application of the analysis is made to prob lems involving 1) dimensional stability and alteration of residual stresses, 2) the strain rate dependence of tensile response, and 3) the effect of residual thermal stress relaxation upon creep in laminated composite plates under mechanically applied loads.