Non-destructive investigation of quasi-static indentation damage to C/SiC composites and its effects on compressive properties

Abstract

Impact damage was introduced into C/SiC composites by a quasi-static indentation method. Damages with different indentation depths were detected by non-destructive testing (NDT) technologies of thermography, X-ray radiography and ultrasonic C scan, and then the detection resolutions were compared. Effects of the impact damages on the retained compressive strengths of the C/SiCs were investigated. Results indicate that when the indentation depth is <0·5 mm, the C/SiCs reveal the linear elastic behaviour with invisible damage for three NDT methods. Once the indentation depth is >0·75 mm, thermal images and ultrasonic C scan are able to detect the obvious damage, while X-ray radiography did not detect any damage up to the indentation depth of 1·5 mm. The retained compressive strengths decreased gradually with increasing indentation depth, and the descent rate of the compressive strength suddenly increased when the indentation depth is >1·5 mm.