Thermal ageing degradation mechanisms on compressive behavior of 3-D braided composites in experimental and numerical study

This paper reports the thermal ageing degradation mechanisms on compressive damage behaviors of pure epoxy resin and 3-D carbon fiber/epoxy braided composites. The epoxy resin and the 3-D braided composite have been aged in air for 1, 2, 4, 8, and 16 days at 180 °C. The compressive testing results and the scanning electron microscope (SEM) observations revealed that the epoxy resin degradation only occurred within regions close to surface layer. The inner parts of the epoxy resin were protected from the ageing oxidation by the outside oxidized layer. The compressive behaviors degradation of the braided composite is attributed to the epoxy resin degradation and interface debonding. The numerical study (Finite element analysis, FEA) illustrates the interface crack propagation. The interface degradation and crack propagation are the main mechanisms of the compressive behaviors degradation after the several-day's high temperature ageing.