Device and method for measuring residual stress on surface of work piece based on laser ultrasonic

Abstract

The invention discloses a device and a method for measuring the residual stress on the surface of a work piece based on laser ultrasonic. The method comprises the following steps: (1) placing a to-be-measured work piece under a vibrating mirror, and placing a piezoelectric sensor on the surface of the work piece and connecting the piezoelectric sensor to an oscilloscope; (2) using pulse laser to excite a surface wave on the surface of the work piece after the pulse laser is focused by the vibrating mirror, obtaining a surface wave signal R1 through the piezoelectric sensor, and obtaining the arrival time t1 of the surface wave; (3) making the pulse laser move longitudinally through scanning by the vibrating mirror, and repeating the step (2) to obtain a surface wave signal and obtain the arrival time of the surface wave; (4) obtaining the surface wave velocity distribution of the work piece on the longitudinal movement line through calculation; (5) laterally moving the piezoelectric sensor along the surface of the work piece, and after each lateral movement, repeating the steps (2)-(4) to obtain the surface wave velocity distribution of the surface of the work piece on different longitudinal movement lines; and (6) calculating the distribution of residual stress on the surface of the work piece according to the theory of acoustic elasticity and the surface wave velocity distribution. The residual stress on the surface of a work piece can be detected rapidly and nondestructively.

Description

technical field [0001] The invention relates to the field of non-destructive testing, in particular to a laser-ultrasonic-based measuring device and method for workpiece surface residual stress. Background technique [0002] Today, parts processed from various materials such as metal alloys and ceramics are widely used in important fields such as aerospace, national defense and military industry. In order to ensure the strength and reliability of these parts, it is particularly important to carry out quality inspection and develop measurement equipment, which is the most difficult point of current research. During the manufacturing process, the workpiece is prone to residual stress due to processing technology, welding and heat treatment. Residual stress is the elastic stress that still exists and maintains balance in the material due to uneven plastic deformation. The existence of residual stress will not only reduce the corrosion resistance of the workpiece, but also caus...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the shortcomings of the traditional stress measurement method such as narrow application range, damage to the workpiece, slow detection speed, complex and expensive equipment, etc., and provide a laser ultrasonic-based workpiece surface residual stress measurement device and its method

Images