Effects of off-axis angle on shear progressive damage of 3D woven composites with X-ray micro-computed tomography

This paper presents the influence of the off-axis angles on the shear progressive damage of three-dimensional (3D) woven carbon/epoxy composites. Five kind of samples with different angles, 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees, of the weft and warp yarn orientation are experimentally tested via short beam shear method. X-ray micro-computed tomography (Micro-CT) techniques are employed to identify the internal damage initiation/evolution of 3D woven composites. Results indicate that the off-axis angles have significant effects on the mechanical behaviors, damage change and final failure mechanisms. Furthermore, the ultimate strength of on-axis samples are mainly influenced by the yarn tensile fracture and delamination, whereas those of off-axis samples are largely governed by the debonding and yarn pull-out breakage.