Temperature-dependent pinned joint tensile behavior and failure analysis of CF/PEKK composites

The pinned joint tensile properties and failure behaviors of carbon-fiber-reinforced polyetherketoneketone (CF/PEKK) composites are sensitive to application temperatures. Herein, this study investigated the temperature-dependent mechanical behavior of CF/PEKK composites in a pinned joint configuration, emphasizing the impact on tensile behavior and bearing strength. Utilizing Solvay's CF/PEKK prepreg with a quasi-isotropic stacking sequence, tensile tests were conducted at -150 circle C and 230 circle C. At -150 circle C, increased load-pin displacement stiffness was observed, attributed to reduced polymer chain mobility, leading to increased peak load and concentrated bearing area around the pin contact region. Conversely, at 230 circle C, a substantial reduction in stiffness and peak load was evident, emphasizing the severe deterioration of pin-load strength. Fracture analysis revealed distinct failure modes at different temperatures, highlighting localized compressive failure at -150 circle C and severe permanent bearing failure at 230 circle C. Understanding these temperature-dependent behaviors is critical for optimizing CF/PEKK composite applications in diverse industrial settings, providing insights for enhanced performance and reliability. The findings offer valuable information on the material's behavior under extreme temperature conditions, contributing to the design and application of CF/PEKK composites in various industrial scenarios.