Experimental Investigation on Laminar Dynamic Compression Behavior of Quasi-3D Needle-Punched Cf/Sic Composite at Room Temperature
准三维针刺C_f/SiC复合材料室温层向动态压缩力学行为的实验研究

To evaluate the influence of strain rate on laminar dynamic compression characteristics of quasi-3D needle-punched Cf/SiC composite, uni-axial compressive experiments were carried out at the strain rate ranging from 10-4 to 6.5×103s-1 at room temperature. Experimental results show that the dynamic compressive strength distribution obeys Weibull distribution due to the inevitable heterogeneous distribution of defects as gas-holes. Catastrophic brittle failure was not observed for the specimens tested at different strain rates. Instead, despite of the decrease of true stress with true strain after the stress reaches its compressive strength, the material still possesses a relatively high load-bearing capacity. It is also found that the compressive strength of the material increases obviously with the strain rate, and presents a linear relation with logarithm strain rate. Optical and scanning electron microscope (SEM) images of specimen's fracture surface indicate that the failure pattern of material varies with the strain rate applied. Under quasi-static loading, shear failure and delamination play important roles in the fracture process. However, split pattern is observed to feature the failure mode under high strain rate dynamic loading.