Rate-dependent tensile failure behavior of short fiber reinforced PEEK

Polyetheretherketone (PEEK) and two types of short-fiber (carbon fiber and glass fiber) reinforced PEEK were investigated under uniaxial tensile tests of various strain rates. The strain rate varies in the range between 10⁻³ and 10³ s⁻¹. The paper aims to show the rate dependency of mechanical properties of short-fiber reinforced PEEK, and the relationship between its failure behavior with strain rate and fiber type. High-speed camera system and digital image correlation technique were employed to measure the evolution of strain distributions. Scanning electron microscopy (SEM) was introduced to examine and analyze the failure mechanisms. The results indicated that the ultimate stresses of PEEK and PEEK composites presented little sensitivity against strain rates, while the failure strain of pure PEEK decreased and the failure strain of PEEK composites increased apparently with the increase of strain rate. Also, carbon fiber reinforced and glass fiber reinforced specimens showed differences in sensitivity to strain rate and failure mechanisms, the latter of which is further confirmed by in-situ SEM tensile tests.