Compressive Mechanical Properties of [0°/90°]_s Glass Fiber Epoxy Laminate

Compressive mechanical properties of [0/90°]_s glass fiber epoxy laminate at direction angle 0°, 45° and 90° are studied. A material test system is adopted to analyze their quasi-static properties, while Φ 14.5 mm split Hopkinson pressure bar (SHPB) apparatus is used to investigate the dynamic characteristics under high strain rates. The results indicate that quasi-static and dynamic properties of glass fiber epoxy laminate at direction angle 0° and 90° are nearly identical, but differ from those at 45°. The specimens at direction angle 0° and 90° experience a quick-loading-quick-unloading process, while those at direction angle 45° experience a quick-loading-slow-unloading process. The experiments exhibit that maximum stress and critical strain under high strain rates are much higher than those under low strain rates. After impact, the specimens are delaminated between plies. The specimens at direction angle 45° probably absorb more energy because of their more fiber delamination. The specimens at direction angle 0° and 90° experience less but heavy delamination to result in a quick-loading-quick-unloading process. On the contrary, those specimens at 45° experience more but incomplete delamination to lead to a quick-loading-slow-unloading process. It can be concluded that strain rate has strong effect on the damage stress and critical strain, so it should be taken into account under dynamic loading conditions.