The Experimental Study of the Strain-Rate Dependence of a Unidirectional Reinforced Gr/Al Metal Matrix Composite

Abstract

Loading and loading-unloading tests of a unidirectional reinforced Gr/Al metal matrix composite have been carried out using a self-designed tensile impact apparatus, and quasi-static tensile tests have been performed on the Shimadzu-5000 testing apparatus. The stress/strain curves of composites have been obtained in strain rate range from 0. 0005 s^{− 1} to 1300 s⁻¹. The experimental results show that complete stress/strain curves of the material can be divided into two parts: the nonlinear elastic brittle deformation and residual deformation. The tests results also clearly indicate that the Gr/Al composite is a rate-sensitive material; namely the strength, failure strain and residual strength of composite all depend on strain rate. Statistical analysis and models were used to obtain the mechanical parameters for composites and their relationship with strain rate from experimental results. The simulated stress/strain curves from the model are in good agreement with the test data. The theoretical model and test results show that the shape parameter β and the scale parameter σ₀ are both independent of strain rate. The constituent, Gr fibers in Gr/Al composites, can be regarded as a rate-insensitive material, and the strain rate effect of Gr/Al composites is mainly caused by the Al alloy matrix.