Prediction of the macroscopic fracture toughness of a composite/adhesive interface with periodic surface microstructures

We developed a formula for predicting the macroscopic fracture toughness of a composite/adhesive interface with periodic surface microstructures. The formula is an expression of the total energy consumption along the interface averaged by the macroscopic crack length. The formula takes the effect of the crack kinking energy into consideration to compensate for the difference between the otherwise predicted consumed energy and that determined by finite element (FE) analysis. The predictions of the developed formula indicate that the macroscopic fracture toughness increases with increasing aspect ratio and decreases with decreasing height of the microstructures, which is in agreement with the findings of our previous studies on crack growth analysis using a cohesive zone model. The validity of the formula was investigated using microstructures of various shapes and sizes, and good agreement was observed between its predictions and the results of FE analyses.