Bridging tractions in mode I delamination: Measurements and simulations

This paper discusses the results of bridging tractions in mode I delamination specimens. Bridging laws determined from a novel technique using distributed strains and an inverse-numerical technique are compared to those obtained using a method based on the experimental measurements of energy release rate and crack opening displacement. Both types of bridging laws are implemented in a numerical model that uses cohesive elements to calculate strains along the FBG and to predict crack growth progression in a double cantilever beam specimen. Global force–displacement responses are well-described by a cohesive model using both experimental bridging laws, however, the J-integral method requires an additional assumption about the length of the bridging zone. In addition, using the cohesive model, the crack tip position and longitudinal strains are more difficult to simulate due to the need for additional parameters (i.e., initial stiffness, maximum stress) required to describe the crack initiation behaviour of the cohesive elements.