Research on High-Frequency Vibratory Stress Relief for Small Assembly

To relieve the residual stress in small assembly, a method called high-frequency vibratory stress relief was researched. Microscopic origin of residual stress was analyzed according to the theory of crystal dislocation, which shows that the appeared unstable dislocations and localized energy concentrating are the main reason to produce residual stress. And then the mechanism of high frequency vibratory stress relief was studied through the dynamic model of dislocations, which is that the microscopic grains on the dislocations will move severely and go back to their original positions when the workpiece is excited at the higher resonant frequency, and thus the number of dislocations will become less and less so that residual stress is relieved. An experiment was designed to relieve the residual stress on a small welding specimen. The results prove that the method of stress relief on small-assembly is effective. Finally, the metallographic analysis also proves the mechanism of the method. The method could play an important role in the stress relief for MEMS devices