Impact of wrinkle defects on failure behavior of L-shaped laminates: Experimental and numerical study

Abstract

The mechanical responses and failure evolution process of L-shaped composite laminates with effect of wrinkle defects were investigated using experimental and numerical methods. In experimental study, L-shaped laminates containing different magnitudes of wrinkle defects were prepared with the aid of ‘transverse-strip’ method. The loading capability and damage propagation of L-shaped samples containing wrinkle defects were investigated within bending test and compared with ones of the intact samples. In numerical study, a progressive damage failure model was created based on 3D Hashin failure criterion. Afterwards, the numerical model was applied to predict the evaluation of stresses distribution and failure mode during failure process. The mechanism of wrinkle impact on the failure behavior of L-shaped laminates was explored further. Test result shows that wrinkle defects significantly reduce the loading capacity of L-shaped laminates and the spatial extension characteristic of delamination damage evolution is changed from the layer-by-layer extension to the aggregation extension of wrinkle area. The numerical predictions consist with the experimental observations. It is revealed that concentrations of transverse stress and out-of-plane stress at wrinkle area are the dominant factors response for the premature failure. In addition, the stress concentrations in wrinkle area destroy the tendency of layer-by-layer damage, leading to the wrinkled samples to exhibit agglomerated extended failure characteristics. The above-mentioned researches can provide a strategy to assess the structural integrity of L-shaped laminates containing wrinkle defects and determine their design of damage tolerance.