Modeling Nonlinear and Time-Dependent Behaviors of Polymeric Sandwich Composites at Various Environmental Conditions

Polymeric sandwich composites are appealing for lightweight structures that require high strength and stiffness such as parts of aircraft, marine vessels and wind turbine blades. During service, polymeric sandwich composites are subjected to static and cyclic mechanical loading, in addition to a constant exposure to hostile environments. In addition, one of the characteristics of polymers is their prominent viscoelastic response when subjected to mechanical loading and the viscoelastic response of polymers becomes more pronounced at elevated temperatures and high humidity. Coupled mechanical loading and hostile environments cause the constituents of the sandwich structures to experience different time-dependent behavior and degradation, leading to complex failure mechanisms in sandwich composites. The aim of this study is to be able to predict the performance of sandwich composites subjected to mechanical loading histories and various environmental conditions, by incorporating knowledge of the behavior of each constituent (skins and core). We present experiments and numerical analyses in order investigate the overall mechanical response of two sandwich composite systems and their constituents, immersed in fluid at 50 °C. It is seen that different failure behaviors are observed in the two sandwich composites, which are strongly influenced by the response of the constituents.