Determination of the in-plane shear modulus of unidirectional carbon fiber-reinforced plastics using digital image correlation and finite-element analysis

Accurate in-plane shear properties are essential to simulate the mechanical behavior of fiber-reinforced laminated composites. Herein, a digital image correlation technique was used to analyze unidirectional carbon fiber-reinforced composites by three shear-test methods (±45° in-plane, Iosipescu, and V-notched rail shear tests), focusing on the uniformity of shear deformation during each test. The V-notched rail shear test imposed the most uniform shear deformation. This test, however, still imposed non-uniformity around the deformation regime for the in-plane shear modulus calculation, which needed to be accommodated. The non-uniformity was virtually characterized by a combination of various material properties using finite-element analysis. A universal correction factor of 0.925 resolved the non-uniformity involved in the V-notched rail shear test. This enabled the in-plane shear modulus of unidirectional carbon fiber- or glass fiber-reinforced composites to be accurately determined.