Quantitative testing of residual deformation in plate with varying thickness based on nonlinear ultrasound

The purpose of this research is to obtain the method of measuring the residual deformation of plate with varying thickness (PWVT) based on nonlinear ultrasound (NLU) quantitatively. The arrangement of residual tensile deformation in PWVT was observed by optical microscope (OM) and simulation. The results showed that the residual strain increased linearly in the direction of deformation. Based on the arrangement of residual strain, the equation of stress wave in PWVT was established and the approximate solution which was verified by the finite difference method (FDM) was calculated. According to the calculation which presented the law of the ultrasound's propagation, a quantitative method to measure the residual deformation of PWVT was proposed. Further, the feasibility of the method was verified in experiment. This study provides a reference for the application of NLU in the test of residual deformation in irregular structures.