Effect of fiber reinforcement and fabrication process on the dynamic compressive behavior of PEEK composites

This paper investigates experimentally the dynamic compressive behavior of short fiber reinforced polyetheretherketone (PEEK) composites, with a specific focus on the effect of strain rate, fiber reinforcement and fabrication process. Hopkinson compressive bar system is employed to test the specimens with strain rate varies from 800–2500/s. Ultra-high speed camera system is used to record the deformation and failure process. Scanning electron microscopy (SEM) is introduced to examine the fracture surface, and to analyze the failure mechanism and its rate dependency. Three different types of PEEK composites are studied and compared to investigate the sensitivity of failure mechanism to fiber reinforcement and fabrication method (injection and extrusion). The results indicate that the ultimate stresses of PEEK and PEEK composites present different levels of sensitivity against strain rates, while the failure strain of PEEK composites decrease with the increase of strain rate. The strain rate dependency is associated with the increase of interface toughness under higher strain rate. The experimental results also identify the presence of phase transformation for matrix material during the high-rate compressive failure. The sensitivity of failure behavior against fabrication process is found to associate with the difference of fiber distributions.