Effect of residual stresses on a micromachined z-axis vibrating rate gyroscope

The design of mechanical structures depends upon characterizing the stress/strain state in these devices under the combined influence of both loading and residual stresses. The performance of the dynamic structures is strongly influenced by residual stresses. Understanding of the behavior of gyroscopes in presence of residual stresses and ability to relieve the stresses are essential for improving the performance. In this paper, we briefly analyze the cause of residual stresses. The effect of residual stresses on natural frequencies of the drive mode and sense mode is theoretically analyzed. The FE model of the z-axis gyroscope is built to investigate the relation between the frequencies and the residual stress by model analysis. Methods for residual stress relief are presented. The results of the simulation demonstrate that the performance of the gyroscopes with serpentine beams and stress relief slots can be improved significantly.