Ultrasonic and X-Ray tomography inspection of a woven glass reinforced composite damaged by drop weight impact

International audienceThe present paper deals with the investigation of a polyamide 6.6/ 6 reinforced with woven glass fibers response to drop weight solicitations. The chosen impact energies were considered in order to remain in the barely visible impact damage domain (BVID). The main objective of this project is to perform a quantitative and a qualitative study of the induced damage as well as its detectability. To do so, several nondestructive testing methods were used. The different damage mechanisms, relative to drop weight tests, were identified using X-Ray tomography. As a result, each damage mechanism was visualized as well as the propagation network of the cracks and the delamination. Two C-Scan configuration, namely in transmission and in pulse/ echo, were used for the purpose of, first, detecting the damaged area and then extracting information relative to residual damage on the surface i.e estimation of the depth and the diameter of the permanent indentation (PI). These information were later validated using a method that is based on the measure of the flatness of the surface. A link was established between the PI measures and the different damage mechanisms detected using X-Ray tomography. The final section of the paper was about a guided waves based method that was employed in order to analyze the effect of drop weight impact energies on the propagation, the transmission and the parameters characterizing the wave. The influence of the impact energy on the time of flight and also on the frequency response of the emitted signal was observed. An analysis of the induced damage effect on the dispersion properties of guided waves is also proposed