Numerical and experimental analysis of delamination of Nomex honeycomb core from the Carbon/Epoxy facesheet in a sandwich structure

In this research, mode I delamination fracture is investigated. A sandwich beam with an initial delamination between one skin and core inspired from double cantilever beam (DCB) has been made for evaluation of the critical strain energy release rate. The problem with this specimen is the apparition of the mixed Mode I+II fracture in some asymmetric specimen. This is caused by the difference between the flexural rigidity of the lower arm and the upper arm. In this research, a rail fixture and a manual control at the free side of the specimen, the failure in mode II was eliminated. The results of the experiments were compared with results of numerical solution and modified elastic foundation theory. The strain energy release rate was calculated using the compliance calibration method and least squares method and the results were compared. Thus pure Mode I delamination has been occurred. In result the rail fixture leaded to a small scatter between numerical and experimental results.