Study On Ultrasonic Testing Technology For Thin Wall Cylinder And Defect Recognition Algorithm

When a shell is fired, its cartridge will bear high temperature and high pressure. In this case, if there are cracks, inclusions and other defects in the inner or outer wall of the cartridge, it will cause-serious safety accidents. Therefore, in order to ensure security, nondestructive inspection for cartridge shell is needed. Cartridge shells belong to the thin-walled cylinder (thickness between 0.8mm～1.2mm). This paper focuses on non-destructive testing techniques and defect recognition algorithm of longitudinal defects in the inner or outer wall of the cartridge.For the plate component with thickness less than 2mm, the traditional transverse wave detection and longitudinal wave detection cannot achieve a very good detection effect because of the disadvantages of big noise, short sound path and weak echo signal. Lamb wave is a form of guided wave usually used in ultrasonic testing. Different with point by point scanning of conventional ultrasonic testing, Lamb wave detection can scan a line, and the send and receive probe can be placed in the same side of the test pieces, which makes it has fast and efficient characteristics transverse and longitudinal waves can not be compared. But the Lamb wave’s modes and dispersion characteristics make the analysis of the data becomes very complicated. For this problem, study on Lamb wave in ultrasonic nondestructive testing was made and the method of Lamb wave water immersion testing was put forward in the paper, which was used in nondestructive detection of thin-walled tubular component. Defect signal and the echo signal were analyzed. According to the periodicity of the defect signal and the characteristic of energy difference between defect signal and interference signal, loss compensation algorithm was proposed, which can realize the effective identification of the defect signal and meet the needs of online production.