1. owth in [0/90]2sIM7/5250-4 laminates with both free-edges and embedded-edges subjected to temperaturecycles between room temperature and liquid nitrogen temperature. The free-edge samples formed cracks early and severe crack densities were observed in all plies except 3 and 6, which resisted cracking until after 1,000 cycles and accumulated only a low density of cracks through 2,600 cycles. A second round of testswere performed by applying a layer of epoxy to the free-edges of the samples prior to cycling. The epoxy effectively embeds the fiber ends altering the micro-stress field and resulted in a large decrease in crack formation in all interior plies. The surface ply pair 1,8 with embedded-edges required more cycles to initiate cracking but then accelerated and actually appeared to be reaching a saturated state of about 10 cracks per centimeter after only 1600 cycles. These changes demonstrate that free-edge micro-stresses have a strong effect on the formation of transverse matrix ply cracks in this balanced, symmetriclaminate. of the Air Force Resea
2. Thermally induced damage in composite laminates: Predictive methodology and experimental investigation