The application of J integral to measure cohesive laws under large-scale yielding

A method is developed to obtain the mode I cohesive law of elastic-plastic materials using a Double Cantilever Beam sandwich specimen loaded with pure bending moments. The approach is based on the validity of the J integral for materials having a non-linear stress-strain relationship without unloading of any material point. This assumption is not met exactly as there is a small where the material unloads. To examine the error of the method, a numerical parameter study is performed for a wide range of material and specimen parameters. The error of the method is below 16% and thus the method can be used to measure cohesive laws including their shape. (C) 2016 Elsevier Ltd. All rights reserved.