Effect of thermal shock cycling on the creep behavior of glass-epoxy composites

Abstract

Abstract The aim of the present work is to investigate the effect of thermal fatigue on the creep and recovery behavior of polymer-matrix composites (ET441 epoxy resin, reinforced with woven E-glass fibers). For this purpose, 3 h creep followed by 3 h recovery tests were performed to specimens, which have previously been subjected to a certain number of thermal cycles (from +50 °C to −27 °C). It was found that the variation of the reduced creep compliance of the materials considered with the number of cycles follows an exponential decay law which was independent on the time period over which the load was applied. In order to better understand such a behavior, a four elements viscoelastic model was applied and the variation of all the four elements with the number of cycles gave a better insight into the observed behavior. In addition, the viscoelastic behavior observed was correlated with the value of the degree of damage and its variation with the number of cycles. It was found that there is a damage threshold corresponding to a certain number of cycles above which damage increases rapidly reaching a plateau where saturation of micro-damage is attained.