Analysis of the mixed-mode end load split delamination test

Composite delaminations are commonly characterized using the double cantilever beam test for mode I, the end-notched flexure test or the end load split test for mode II and the mixed-mode bending test for mixed-mode. For all these tests, the mode mix remains constant and does not vary with the crack length. However, in the mixed-mode end load split test (MMELS), the delamination propagates under a varying mode mix that depends on the crack extension, which is a more realistic scenario. The MMELS test has been previously analysed by different researchers but the resulting expressions are not equivalent. A more accurate alternative analysis of the test, based on the finite element method and the virtual crack closure technique, is used in the present work for comparison. The results are compared to the predictions of approaches presented in the literature and significant findings are found for materials characterization using the MMELS test.