Analysis of mode I delamination of z-pinned composites using a non-dimensional analytical model

We present a non-dimensional analytical model for crack propagation in a z-pinned double cantilever beam specimen (DCB) under mode I loading. Effect of various design parameters on the crack bridging length and apparent fracture toughness are investigated using this model. The efficacy of the analytical model is evaluated by comparing the results with 3D finite element (FE) simulations of the DCB. In the FE model the z-pins are modeled as discrete nonlinear elements. Bi-linear cohesive elements are used ahead of the crack tip to account for the interlaminar fracture toughness of the composite material. The results for load–deflection and crack length obtained from the analytical model and the FE model are compared and found to be in good agreement. The proposed non-dimensional analytical model will be useful in the design and analysis of translaminar reinforcements for composite structures.