Enhanced Tensile Properties and Damage Tolerance of an Unconventional Composite Bolted T‐Joint by Load‐Carrying Laminated Beams

ABSTRACT Improving the tensile performances of composite out‐of‐plane joints like T‐joints has always been a key focus for the connection structures. Based on the unconventional configuration design of composite bolted T‐joints, consisting of an internal laminated skeleton and external skin, load‐carrying laminated beams were incorporated on both sides of the lug skeleton, and the prepreg‐resin transfer molding (RTM) co‐curing process was improved in this study. Subsequently, tensile tests were conducted on new configuration T‐joints. The results indicate that the new configuration T‐joint exhibits excellent tensile performances, with the proportional limit load and ultimate load improved by 29.37% and 68.34%, respectively, compared to the original configuration T‐joint. Its specific elastic stiffness and specific proportional limit load reach 130.92% and 260.99% of the same‐sized 2A12 aluminum T‐joint. The main failure modes become large‐scale skin delamination and skeleton delamination around the bolt holes in the base panel, with more diverse damage progression paths, thereby improving the damage tolerance capability of the joint. Additionally, since skin delamination damage at the junction between the corner area and base panel area represents the non‐negligible initial damage, it can be judged whether the joint is within the linear load‐carrying segment according to the strain change at this zone.