Dynamic compressive mechanical properties and a new constitutive model of 2D-C/SiC composites

The layer-directional compressive properties of 2D-C/SiC composites were investigated at strain rates ranging from 10(-4) to 2.8 x 10(3) s(-1). The quasi-static experiments were performed using the electronic universal testing machine, and the dynamic experiments were conducted by the split Hopkinson pressure bar system. The results show that the dynamic compressive stress-strain curves are non-linear. The failure strength and the elasticity modulus vary linearly to the logarithm of the strain rate, and the failure strain reduces with an increasing strain rate. Scatter of dynamic compressive failure strength obeys Weibull distribution and the Weibull parameter m is 5.27. The damage angle of dynamic compression is larger than that of static loading. Observed on SEM, the ruptured surface is smooth at high loading rate and more cracked fibers appear in the specimens than at lower strain rate. Based on the experimental results, a new constitutive model is proposed in this paper. (C) 2008 Elsevier B.V. All rights reserved.