ANALYSIS OF MIXED MODE I/II/III FRACTURE IN FOAM CORE SANDWICH STRUCTURES USING IMPOSED DISPLACEMENT SPLIT CANTILEVER BEAMS

Static fracture in foam cord sandwich structures under mixed mode I/H/111 loading conditions was studied theoretically. In order to generate such loading conditions, a thread guide was used to impose in plane displacements of the lower crack arm of a sandwich Split Cantilever Beam (SCB). The upper crack arm was loaded by a transverse force. A three-dimensional finite element model of the imposed displacement sandwich SCB configuration was developed. The fracture was studied applying the concepts of linear-elastic fracture mechanics. The strain energy release rate mode components distribution along the crack front was analyzed using the virtual crack closure technique. The influence of the imposed displacement magnitude and the crack length on the fracture was evaluated. The effect of the sandwich core material on the mixed-mode fracture was studied. For this purpose, finite element simulations were carried-out assuming that the core is made by different rigid cellular foams. It was found that the strain energy release rate decreases when the foam density increases.