Two-position impact behavior and interference mechanism of CFF/PEEK thermoplastic composites

• A novel LVI experiment for two positions was designed and performed. • LVI response is synergistically affected by impact energy and impact spacing. • Large impact energy and small impact spacing can induce more severe LVI damage. • Interference mechanism of two-position impact is revealed based on LVI response. Previous studies on low-velocity impact of fiber reinforced polymer (FRP) composites mainly focused on single-location impact (including single and multiple), while completely ignoring the multi-position impact common in practical engineering. This paper aims to investigate the mechanical response and damage behavior of carbon fiber fabric reinforced polyetheretherketone (CFF/PEEK) thermoplastic composites subjected to low-velocity impact (LVI) at two positions sequentially. Typical LVI responses of CFF/PEEK composite laminates at four impact spacing and three impact energy are analyzed comprehensively and deeply. A comparative analysis of impact damage including dents, cracks and internal delamination damage are performed. The results show that the mechanical response and damage morphology of two-position impact are induced synergistically by the impact spacing and impact energy. The coincidence degree of LVI response curves and delamination damage areas are the direct evidences reflecting the interference degree of the two impacts. For the two impacts with interference, the energy absorption by the two impacts mainly depends on the impact damage modes induced by different impact spacing and impact energy. These studies provide a technical idea for exploring the LVI behavior of FRP composites under multi-position impact.