Time-temperature dependent failure analysis of open-hole composite laminates under compression loading

Taking time-temperature dependent properties of composites into consideration, storage modulus segments of cured 5228A resin was obtained within a certain experimental window by dynamic mechanical analysis (DMA) under different temperatures. Master curve was constructed by closed form shifting (CFS), which corresponding shift factors resulted from. Constant strain rate (CSR) compression master curves were established based on accelerated testing methodology (ATM), studying quasi-isotropic open-hole CCF300/5228A laminates of two kinds of layup. By means of macro photography and C-scan, the damage processes and failure modes were investigated under different temperatures. The results show that dynamic mechanical properties of resin decrease with the increasing time even though with temperature range below the glass transition temperature; strength of thicker-ply laminates is more sensitive to time and temperature changes, while thinner-ply ones possess better damage tolerance property; the dominant factor of final failure tends to be micro-bulking of fiber instead of delamination as temperature rises and loading rate decreases.