DCB test simulation for stitched CFRP laminates by using interlaminar tension test results

A mechanical model for the delamination extension of stitched laminates and 3-D orthogonal interlocked fabric composites has been developed by using 2-D finite element method to simulate experimental results of their DCB tests. The fracture phenomena around the through-the-thickness thread, such as debonding from the in-plane layer, slack absorption, fiber bridging, and the pull-out of broken threads from the in-plane layers, are introduced to the analytical model of the through-the-thickness yarn, and this model is determined from the result of the interlaminar tension test of the specimen including only one through-the-thickness yarn. The present FEM model is applied to some stitched laminates and a 3-D composite, and the analyses indicate good agreement with the experimental results, including the load-displacement curve and Mode I strain energy release rate. Since the present model of FEM analysis can simulate the experimental results in the DCB test for the stitched laminates and the 3-D composite, it is proven that this innovative method of the interlaminar tension test and FEM analysis has a possibility of predicting the result of a DCB test without actually executing the DCB test.