Energy release rate prediction in stiffened-skin structure using a three-dimensional crack tip element analysis

Total energy release rates and energy release rate components are predicted for a stiffened-skin structure that is loaded in bending and which contains a delamination between its skin and a hat-shaped stiffener. This is done using three-dimensional crack tip element and three-dimensional finite element analyses. An isotropic configuration and a variety of graphite/epoxy layups are considered, for which the two analyses are shown to be in good agreement. The results indicate the practicality of, and considerable computational savings that may be achieved by, employing crack tip element analyses for energy release rate assessments in realistic structural geometries. They are also used to qualitatively examine the effects of layup on energy release rate distributions in this geometry.