Development of a Data Reduction Method for Composite Fracture Characterization Under Mode III Loadings

This work is part of a research aimed at developing a reliable data reduction method for a novel test rig for sandwich composites, which is inspired by the Shear Torsion Bending (STB) rig designed for unidirectional composites. The rig performs fracture characterization tests on pre-delaminated composite sandwich specimens subjected to out-of-plane shear loading. An out-of-plane displacement is applied at the end of the delaminated arms using a hydraulic actuator and the corresponding load is recorded. An analytical equation is required to compute the global value of the energy release rate for an imposed displacement. The preliminary work presented in this paper assumes the material to be quasi-isotropic and linear elastic. The mathematical derivation of the energy release rate relies on First Order Shear Deformation Theory and Vlasov theory for non-uniform torsion of beams. The analytical expression is compared with the energy release rate extracted from a 3D FE model of the specimen using the compliance method.