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 fiber-reinforced composite (FRC) in on-axis ((Formula presented.) and (Formula presented.)) and off-axis ((Formula presented.)) 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. Highlights: Single-bolt and double-bolt joint performances of 3D woven composites Failure investigation of different joint configurations and fiber orientations Effect of matrix toughness on the bearing performance of 3D woven composites Progressive damage development and failure modes of 3D woven composite joints.