Residual stress profiling of an aluminum alloy by laser ultrasonics

In order to effectively determine the residual-stress profile of an aluminum alloy, the measuring method was studied by the laser ultrasonic technique. In this method, surface acoustic waves are generated by a Nd:YAG pulse laser and detected by a heterodyne interferometer. Theoretical analysis shows that the residual-stress profile could be determined by measuring the relative velocity-variation of the surface waves at different locations of the sample. Three samples with no stress, compressive or stretched stress were measured experimentally. The results show that the residual-stress distribution can cause surface waves vary in velocity at different locations, and that this method is an effective technique of nondestructively detecting the residual-stress profile.