Tensile properties and damage behaviors of the prepreg-RTM co-cured composite bolted T-joint with a novel configuration

The tensile properties and damage behaviors of prepreg-resin transfer molding (RTM) co-cured composite bolted T-joints, consisting of an internal skeleton and an external skin, were investigated through experimental and numerical methods. With the validated finite element model, the effects of adding load-carrying beams, the corner radius and the stacking sequence were investigated. Results indicate that the novel T-joint, weighing only 55.7% of an equivalent sized 2A12 aluminum T-joint, can achieve 82% of the aluminum T-joint's tensile stiffness and 107% of its proportional limit load. Damage in the joint initiates near the bolt holes and leads to delamination failure within the skeleton. With load-carrying beams including bolt holes, the tensile stiffness and ultimate load increase to 1.11 and 1.51 times that of the original configuration, respectively, with the final failure mode shifting to the fracture of the base panel. With the final failure mode unchanged, the ultimate load remains essentially unchanged with increasing the corner radius. Under tensile loads, the preferred stacking sequence for the skeleton is [0/+45/90/−45]nS. For the skin, the greater the number of ±45° plies, the higher the ultimate load, while the greater the number of 90° plies, the higher the tensile stiffness.