Simulation of circumferential surface defect characteristics in high-strength screw blanks based on laser ultrasonics

Abstract Based on the propagation principle of laser ultrasonics on the circumferential surface of metal specimens, this paper uses the scanning detection source method and the scanning excitation source method to locate and analyze. The defects on the circumferential surface of bolt blanks. A comparison reveals that the amplitude change of the ultrasonic wave peak near the defect is significantly greater when using the scanning excitation source method, which is more conducive to defect identification. By analyzing the relationship between the time difference of characteristic echoes Rr, R’r generated on the circumferential surface and the depth of defects, a quantitative calculation method for defect depth is studied. Through numerical fitting and comparative verification, this method can achieve the characterization of 0-1.5 mm defect depth within the allowable error range.