A New Ultrasonic Testing Method for Residual Strain Measurement With Laser Grating

In this paper, a new and noncontact ultrasonic testing (UT) method using laser grating is proposed for the residual strain measurement. In this method, the laser grating technique is utilized to generate coherent surface waves with a specific wavelength in the narrow frequency band. A numerical method based on the finite element model is established to simulate the coherent surface waves generated by the laser grating in prestrained media to determine the capability and sensitivity of this method. The relationship between the strain and frequency spectrum of the coherent surface wave is studied. Finally, an experiment validation of the laser grating-based UT of residual strain is carried out using specimen with different plastic strains by the tensile test.