Friction influence on the Compression-After-Impact test response of thin-walled Carbon-Fibre-Reinforced-Plastics with buckling development

Abstract

The impact damage to thin-walled Carbon-Fibre-Reinforced-Plastic (CFRP) components remains a critical concern in aircraft structures. Standardised Compression-After-Impact (CAI) test procedures, commonly involving 4 mm thick CFRP plates, are used to study the failure mechanisms of impact-damaged composite structures. However, these procedures do not consider the influence of imperfections and global buckling on thin-walled CFRP structures. This study focuses on the behaviour of 2.13 mm thick CFRP plates under CAI test loading, where global buckling develops, leading to increased loads carried by the knife-edge supports of the device (located at the unloaded plate sides, aligned with the compressive loading). The influence of friction between the knife-edges and the plate is investigated via Finite Element models and compared with experiments, revealing its influence on the buckling shape, failure load, and rupture of the plate. In summary, friction is a physical phenomenon that, contrary to the current state of the art, should be addressed for thin-walled CFRP in CAI testing when global buckling develops.