Ultrasonic investigation of fatigue, tensile damage, and impact damage in woven glass-fiber fabric reinforced composites with comparison to X-ray tomography

This work was done on woven glass-fiber fabric reinforced composite samples. Those materials exhibit a complex anisotropic evolution of defects induced by several damage mechanisms. In order to non-destructively evaluate the damage accumulation within this material, a methodology based on the measurement of the complete stiffness tensor is considered. After validation of the detectability of increasing damage state with this method, a new damage indicator is proposed to thoroughly quantify it. Samples were damaged by tensile tests (quasi-static and fatigue) at increasing stress levels along and out-of fibers axis. Afterwards, drop-weight impact is performed to consider several damage situations. Finally, an X-ray tomography is conducted to identify the damage mechanisms as well as the evolution of the void volume fraction. It is shown that this evolution has the same tendency with the ultrasonic damage indicator.