Impact response and damage evolution of triaxial braided carbon/epoxy composites. Part I: Ballistic impact testing

Abstract

To investigate the high-velocity impact response and damage evolution of the triaxial braided composite fan case, a series of ballistic impact tests using blade-like projectiles were conducted. Cylindrical projectiles of the same cross-section perimeter were also employed to identify the influence of projectile geometry. In addition, satin woven composites were tested for comparison with respect to failure modes and damage shape. Experimental results indicate that the main failure modes for the two different fiber reinforcement architectures are similar, that is, fiber shear failure and matrix crush failure in the impact surface and fiber tensile failure, fiber pull-out, matrix cracking, and delamination in the exit surface. The damage area in the exit surface is diamond-shaped for satin woven composites while rounded or elliptic for triaxial braided composites according to projectile geometry. The triaxial braided composites have an improved ballistic resistance and higher ballistic limit than satin woven composites. Based on damage area and failure modes observed from experiments, ballistic behavior was predicted using an analytical model, which proves to be accurate enough.