Flexural progressive damage and failure behavior of carbon-aramid/epoxy hybrid woven composites

Two kinds of carbon aramid/epoxy hybrid woven composite specimens with different fiber orientations were prepared. The progressive flexural damage behaviors of the composites were studied. The failure process was monitored in real time by acoustic emission during the test, and the characteristics of the acoustic emission signals originating from the damage were deeply studied. In addition, the internal damage initiation/evolution and failure mechanisms were characterized by X-ray micro-computed tomography. The results show that composite specimens exhibit higher strength and obvious quasi-brittle damage behavior when carbon fiber orients along the loading direction, and the macroscopic failure is mainly shear fracture, which propagates in the direction of thickness, and the damage is dominantly distributed above the neutral plane of specimen. When aramid fiber orients along the loading direction, composite specimens show high ductility and the failure modes are mainly ply fracture at the bottom, delamination (inter-ply delamination and intra-ply delamination) and tensile fracture of the tows. The combination of acoustic emission and X-ray micro-computed tomography analysis provides an insight for further elucidation of the progressive damage initiation/evolution and failure mechanism of composites.