Mixed-Mode II/III Fracture in Foam Core Sandwich Beams

This paper is motivated by the fact that no mixed-mode II/III fracture studies of foam core composite sandwich beams were found in the literature available. In order to generate mixed-mode II/III crack loading conditions, it is proposed here to load an End-Loaded Split (ELS) foam core composite sandwich beam in torsion and bending by applying a transversal load at one of the beam corners. The fracture behavior was studied theoretically using the methods of linear-elastic fracture mechanics. The strain energy release rate mode components distribution along the crack front was analyzed by the virtual crack closure technique. For this purpose, three-dimensional linear-elastic finite element simulations of the ELS foam core sandwich beam configuration were performed. The analysis yielded non-uniform distribution of the strain energy release rate mode components along the crack front. The influence of the sandwich beam core material on the mixed-mode II/III fracture was studied assuming that the core is made by three different rigid cellular foams. The mixed-mode I/II/III fracture was analyzed too. The results obtained indicate that the mixed-mode II/III and the mixed-mode I/ II/III fracture performance of the sandwich beam can be improved using a foam core with higher density.