Further developments in testing and analysis of the plate twist test for in-plane shear modulus measurements

The plate twist test for testing the in-plane shear modulus of composite materials is analysed. In the proposed test set-up the loads are not applied to the corners of the plate. This makes the test easier to perform than the original plate twist test. Based on a strength of materials approach, an analytical expression is found for the correction factor that accounts for the shifted position of the loading points. The analysis is made without making the assumption of equal bending stiffness in the diagonal directions of the plate, and can thus be applied for off-axis tests on orthotropic or lower symmetry composite materials.