Research On Digtal Ultrasonic Flaw Detection System

Ultrasonic flaw detection is one of the most widespread technique in Non-Destructive Testing (NDT). It is widely used in industrial fields because it can detect the flaws in and on the metal and non-metal material.In this paper, the status and the development of ultrasonic flaw detection technique at home and abroad are introduced and the basic principle of ultrasonic flaw detection is presented. In order to meet the need of the fast non-destructive examination on plane, the research direction of the paper is determined. The four-channel ultrasonic non-destructive testing system is introduced based on pulse ultrasonic detecting theory. With C8051F340 high performance processor as its control core unit, the system adopted PCI8001 to realize high speed data acquisition. In order to implement the effective evaluation of the flaws, the software of ultrasonic non-destructive testing system is designed based on VC6.0 environment. The system can realize real-time data acquisition and display of ultrasonic wave and can give an alarm automatically when the flaws exist. The digital signal process technique is adopted to analysis the flaw echo, which realized the evaluation of the depth and the size of the flaws successfully. At the same time, the wavelet technique is adopted to denoise in the situation of small signal-to-noise ratio, which enhance and extract the flaw echo successfully and reduce the ratio of misjudge and missing report during the detection. Besides, according to the principle of wavelet modular maximum, we realize the measure of the position of the flaws accurately.We accomplish the design of prototype of ultrasonic flaw detector and build a good platform for ultrasonic non-destructive testing. According to a lot of experiments, it is indicated that the result of the test goes along with the true flaw on the specimen by and large.In the end, the conclusions of this paper are given and the suggestions for further study are made.