Failure modelling and characterisation for pin-reinforced metal-composite joints

Through-thickness metallic pin reinforcements can significantly improve the performance of hybrid metal-composite joints, particularly when failing in the high-energy mode of pin pull-out. However, there is a lack of knowledge on how to promote pull-out across the wide range of joint parameters including geometry and load conditions. Here, a numerical methodology capturing all relevant pin geometry, material and damage characteristics is proposed, and shown to closely match experimental results. This model was then used to characterise pin failure mode and energy as a function of pin geometry across loading ratios ranging from pure tensile to pure shear. The numerical model provides extensive insight into the damage sequence and the interaction of damage mechanisms. The investigation also comprehensively reveals how increasing the shear loading component reduces the pin aspect ratio of height-to-diameter required to maintain pin pull-out. The results add new knowledge and capability for the optimum design of pin-reinforced hybrid joints.