Sound Velocity Difference Calculating Method and Application in Evaluation for Non-uniform Stress

In order to study the response of ultrasonic to non-uniform stress field of aluminium alloy, it is calculated using ABAQUS finite element software that the non-uniform stress field of specimens under different strain. Then, based on the theory of acoustic elasticity, the corresponding ultrasonic velocity difference corresponding to the complex stress field can be obtained To verify the simulation results, 7050-T7451 aluminum alloy samples were applied with the same degree of strain external stress, and the ultrasonic velocity distribution was obtained by ultrasonic scanning. The results show that the stress distribution obtained by simulation are correlated with those of ultrasonic method and they are consistent with the general rule of stress distribution. However, there are some differences between them because ultrasonic method is used to evaluate the superposition effect of stress in the whole thickness direction of the sample. The ultrasonic velocity difference obtained from the simulation of non-uniform stress field is consistent with the measured results, there is a nonlinear increasing relation between the difference of ultrasonic velocity difference and the external deformation, the relation curve between deformation and ultrasonic velocity difference by the two methods are basically the same.