About the influence of temperature and matrix ductility on the behavior of carbon woven-ply PPS or epoxy laminates: Notched and unnotched laminates

Could thermoplastic-based composites be used to replace thermosetting-based composites in high-temperature secondary aircraft structures? The purpose of this work is to establish the ability of a material system to be used in aircraft engine nacelles when subjected to static loadings, with a key upper temperature of 120 °C. In order to provide answers to this question, the thermo-mechanical behaviors of carbon fiber fabric reinforced PPS or epoxy laminates have been compared specifically within the temperature change with 120 °C at the upper bound. The temperature-dependent ductile behavior of laminates is more or less exacerbated, depending on polymers glass transition temperature, and laminates stacking sequence. For both materials, the degree of retention of tensile mechanical properties is quite high in notched and unnotched quasi-isotropic laminates. A Digital Image Correlation technique has been used in order to understand the influence of temperature and matrix ductility on the mechanisms of overstresses accommodation near the hole. In fabric reinforced laminates, the high-temperature results suggest a competition between the mechanisms of damage, and the mechanism of plasticization, enhanced in angle-ply lay-ups. Thus, the highly ductile behavior of TP-based laminates, at temperatures higher than their T_g, is very effective to accommodate the overstresses near the hole.