Failure of short carbon-fiber-reinforced PEEK composites under high strain rate biaxial loading

The dynamic failure of short carbon fiber reinforced polyether-ether-ketone (SCFR-PEEK) composites under biaxial stresses was investigated in this paper. Cruciform specimens were loaded with a biaxial split Hopkinson tensile bar system, and a high-speed camera was utilized to record the deformation and failure processes. A nonlinear numerical model calibrated with dynamic uniaxial tests was used to estimate the stress in the cruciform specimen, in conjunction with strain fields from digital image correlation (DIC) of high-speed camera images. The failure of the cruciform specimen initiated inside the gauge section under all dynamic loading cases, and the numerical strain fields are in good agreement with the experimental ones. The dynamic failure envelope under biaxial stresses was successfully obtained, the failure strain decreased and failure stress increased with strain rate noticeably. The testing method developed here is also applicable for dynamic biaxial testing of many other composites.