Experimental determination of torsion and shear properties of sandwich panels and laminated composites by the plate twist test

A recently developed sandwich plate twist test is employed here for determination of the transverse shear modulus of the core and twist stiffness (D66) of a sandwich panel consisting of a soft (H45 PVC foam) core and glass/vinylester face sheets. The shear modulus of the H45 PVC foam core extracted from the twist test was in good agreement with shear modulus obtained from ASTM plate shear testing of the foam core. D66 values obtained from the sandwich twist test were in good agreement with predictions from classical laminated plate theory. In addition, the twist test was used to determine the in-plane shear modulus of glass/vinylester laminates isolated and as face sheets in sandwich panels with a stiff (plywood) core. The in-plane shear modulus of the face sheets, isolated and as part of a sandwich panel, was in good agreement with shear modulus determined using the Iosipescu shear test. The results point to the potential of the twist test to determine both in-plane and out-of-plane shear moduli of the constituents of a sandwich structure, as well as D66.