Abstract:

Based on ultrahigh sensitivity of the SQUID sensor, the SQUID nondestructive testing is used in nondestructive detection of the internal defect of flat pieces for 3-D  braided composites. The system constructs the theory of circular eddy current distribution in the thin sheet, which is suitable for the SQUID testing requirements. This paper presents flux imaging algorithm for the SQUID detection of the internal defect in flat pieces of 3-D braided composites. The OPENCV was used for processing the flux image and detecting the inside defect condition of the pieces of 3-D braided composites. Experimental results show that the method is accurate to describe the location and size of defects of the detected test piece.The SQUID magnetic flux has good function for detection and location. Compared with the conventional detection technologies such as ultrasonic detection, the SQUID technology is a more advanced nondestructive testing techniques suitable for 3-D braided composites.

Key words: three-dimensional braided composite material, superconducting quantum interference device, defect, non-destructive testing, flux image