Finite element modelling of z-pinned composite T-joints

This paper presents a finite element model (FEM) to analyse the structural deformation, strength properties and delamination fracture behaviour of composite T-joints reinforced with z-pins. The FE modelling involves multi-level analysis of a pinned joint using unit cell and macro-scale structural models. Unit cell model is used to calculate the crack bridging traction loads generated by the elastic and interfacial friction (pull-out) stresses of a single pin within a representative unit cell of the joint. Macro-scale analysis involves modelling delamination crack growth in the pinned joint using a cohesive zone model, which is based on the traction load analysis of a single pin. The FE model was validated using experimental results for a pinned carbon fibre/epoxy T-joint subjected to tensile (stiffener pull-off) loading. The model accurately calculated the crack initiation load, ultimate load, and fracture mode of the pinned joint.