A semi-analytical method for determining the mixed mode I/II fracture resistance and mode mixture of ADCB laminates

The crack tip of the asymmetric double cantilever beam (ADCB) under mode-I loading is often accompanied by a proportion of mode II component, thus it is a typical mixed-mode I/II problem. Characterizing the mixed-mode I/II fracture resistance behavior and mode partition in ADCB laminates is of great significance for studying the mode mixture phenomenon. In this work, a semi-analytical method is proposed to determine the mixed-mode fracture resistance curve (R-curve) and mode mixture of ADCB composite laminates. Considering the use of the equivalent crack length related to compliance, the global crack growth rate ratio correction model is proposed. The results derived from the proposed semi-analytical method is compared with other theoretical methods to verify its effectiveness and wide applicability for ADCB laminates with various material systems and stacking sequences. In contrast, the semi-analytical method with the global crack growth rate ratio correction requires fewer measurement data and gives accurate R-curve results. In addition, it makes the mode partition during the whole delamination growth process with physical meaning.