Features of Three-Point Bending Tests for Determining Out-of-Plane Shear Modulus of Layered Composites

Three-point bending tests are widely used to determine the elastic and shear moduli of polymer matrix composites due to their simplicity. Nevertheless, the accuracy of the elastic constants definition has a significant sensitivity to a degree of anisotropy of the laminates. This work is aimed to analyze experimentally and numerically the capabilities of the bending tests for determining the out-of-plane shear modulus of composites with different degrees of anisotropy. The methodology considering an influence of shear and local deformation effects was used. Finite element modeling was performed for an independent assessment of the accuracy of the methodology. It was found out that the methodology considered allowed one to determine the out-of-plane shear modulus with reasonable accuracy for both unidirectional and woven CFRPs. At the same time, the accuracy of the out-of-plane shear modulus determining is significantly reduced for materials with a low degree of anisotropy, such as woven GFRP.