Moisture effect investigation on the dynamic fracture behavior of unidirectional and woven carbon fiber/epoxy materials

Abstract The mixed-mode fracture response of weathered unidirectional and woven composites was studied. Composites were hygrothermally aged and dynamically loaded by launching projectiles from a gas gun. Hygrothermal aging was achieved by submerging samples in distilled water at a constant temperature of 65°C until a moisture content of 1.5 wt% was achieved. Ultra-high-speed photography combined with digital image correlation was used to obtain the stress intensity factor histories and dynamic fracture toughness of the samples, thus allowing us to compare the material behavior in both pristine and weathered conditions. The experiments presented in this chapter include a more realistic loading condition compared to pure mode-I or mode-II fracture conditions, as such more complex and less intuitive failure modes will be presented. In particular, mixed-mode loading conditions arising from a mode-I loading scenario, and fracture arrest due to transverse fibers in woven laminates.