The Effect of Displacement Constraints on the Failure of MEMS Tuning Fork Gyroscopes under Shock Impact.

Displacement constraints such as stops are widely used in engineering to improve the shock resistance of microelectromechanical system (MEMS) tuning fork gyroscopes. However, in practical applications, it has been found that unexpected breakage can occur on MEMS tuning fork gyroscopes with stops. In this paper, the effects of two displacement constraints on the failure mode of MEMS tuning fork gyroscopes are studied. The MEMS tuning fork gyroscope is simplified to a two-degree-of-freedom (2DOF) model, then finite element analysis (FEA) is used to study the effects of displacement constraint on the gyroscope. The analysis proves that even if the displacement constraint of direct contact with the weak connecting beam is not established, the equivalent stiffness of the gyroscope can be enhanced by limiting the displacement of the movable mass, thereby improving the shock resistance of the gyroscope. However, under the shock of high-g level, displacement constraint with insufficient spacing will cause multiple collisions of the small-stiffness oscillating frame and lead to an increase in stress. The cause of failure and shock resistance of a MEMS tuning fork gyroscope are verified by the shock test. By comparing the results, we can get a conclusion that is consistent with the theoretical analysis.