Simplified Evaluation Method for Shear Moduli of Carbon Fiber Reinforced Plastics

The in-plane and out-of-plane shear moduli (G12 and G23, respectively) of carbon fiber-reinforced plastics (CFRP) require specialized fixtures and setups for measurement due to their anisotropy. In this study, two approaches were employed to evaluate these shear moduli. A finite element analysis was first conducted to determine the optimal specimen geometries for the pure shear test. Subsequently, pure shear tests were performed to determine G12 of the CFRP. However, this method cannot be used to calculate G23 because of the low stiffness and strength of the specimen, in which the fibers were oriented out-of-plane relative to the specimen surface. Therefore, tensile tests were conducted using 90° laminated plates, and the digital image correlation method was employed to evaluate G23. Finally, the obtained results were validated by comparing with the reference data, and good agreement was observed between them.