Study on Propagation mechanism of Stress Corrosion Crack with Laser Holographic Interferometry

摘要

Aiming at high strength steel material in aerial accessory, the crack propagation mechanism of material stress corrosion is studied. The theory of laser holographic interferometry and crack extension mechanism of the material stress corrosion are chiefly discussed. The testing method is presented, which includes monitoring with laser holographic interferometry, fringe-image sampling with CCD camera and image processing. The stress corrosion monitoring system of laser holographic interference is set up accordingly. Using this system, a group of real-tune holographic interference patterns are obtained. In these fringe images, it can be seen that dim-spot position of crack tip moves down and the rule of fringe-space change is gotten. According to the test data, the changing velocity of the surface-separating displacement under a certain hour can be obtained by image processing, which is from 0.038 microns to 0.047microns per minute. At last, the measuring range of the recording medium is discussed, which provides a valid means for damage tolerance design and safe life evaluation.