Bearing performance and damage characteristics of rein-infused thermoplastic 3D woven composites bolted joints

This paper presents a comprehensive study on the single-bolt single-shear (SBSS) and double-bolt single-shear (DBSS) lap joint performance of resin-infused thermoplastic 3D fibre-reinforced composite (FRC) in on-axis (0 degrees and 90 degrees) and off-axis (45 degrees) configurations. The bearing performance and failure mechanisms are compared with thermoset 3D-FRC. The resin-infused thermoplastic 3D-FRC bolted joint shows improved bearing performance in terms of higher ultimate bearing strength, stiffness loss strength, and reduced damage severity than its thermoset counterpart. Additionally, this paper presents a detailed study on the intermediate and final failure mechanisms, obtained from scanning electron microscopy of the interrupted and ultimate bearing tests, to understand damage progression in SBSS and BDSS lap joints at the submicron level. The major damage characteristics of a thermoplastic 3D-FRC bolted joint include plastic deformation and plastic kinking at the hole front tip, which improve the bearing capacity and reduce stress concentration, damage severity, and its deleterious effects.