Effect of material nonlinearity on the toughness evaluation in quasi-static mode II interlaminar fracture toughness tests of composite laminates

In mode II interlaminar fracture toughness tests of composite laminates, the evaluated based on linear elastic mechanics deviates from true due to material nonlinearity matrix. this study, an elastoplastic finite-element analysis was performed a new quasi-static test, i.e., doubly end-notched tension (DENT) investigate difference between perceived energy release rate and J-integral. The effect compared with other tests: three- four-point bend flexure tests. Analysis DENT showed that for given J-integral loading, size plastic zone at delamination crack tip same regardless length. in test respect independent length, smaller flexure-type Furthermore, compliance calibration method applied results reduce evaluation rate.