Extracting Interlaminar Cohesive Laws from Displacement Field Measurements

摘要

Cohesive/interface elements are one of the successful numerical tools that havernbeen recently applied to many different problems and shown good results in modellingrncrack development. However, most applied cohesive laws are hypothetical and are notrnbased on experimental measurements. The aim of this study is to investigate therndamage development at a delaminating interface and to propose a method by whichrnthe mode-Ⅱ traction-separation law can be extracted experimentally.rnTo find the traction-separation law, both variables (traction and separation) need tornbe evaluated separately at the interface. Mode-Ⅱ separation can be found byrnsubtracting the displacements on each side of the interface, however finding the valuernof traction (shear stress) at the interface is more difficult. As a first step, the shearrnstrain field is found from the available displacement field measurements and then, thernshear stress is worked out using the shear constitutive law.rnAfter validating the proposed method against FE simulations, the experimentalrndisplacement field is used to find the traction-separation law. The overall form of therntraction-separation law can be approximated by a trapezoidal shape.