Characterization of nonlinear shear properties for composite materials using digital image correlation and finite element analysis

A method for accurate assessment of nonlinear shear stress–strain relations of composite materials is developed in this work using short-beam shear (SBS) tests. The method is based on a combination of a finite element model (FEM) for stress calculation and a digital image correlation (DIC) technique for full-field measurement of deformation. An inverse problem of generating shear stress–strain curves is solved using an iterative procedure which starts with a beam theory-based closed-form approximation of shear stresses, and updates the stresses through a number of finite element simulations. The method is demonstrated on unidirectional carbon/epoxy SBS specimens. Experimentally-generated strain fields are compared with FEM-computed strain fields to verify accuracy of the developed method. Shear stress–strain data are compared with V-notched beam test results for further verification.