Fault Mechanism Analysis of MEMS Gyroscopes Under High-Overload Environment

High-overload micro-electro-mechanical system (MEMS) gyroscopes can retain an output after impact while exhibiting degraded sensing performance. This study examines a packaged four-mass gyroscope using a coupled mechanical model, transient finite element analysis and a single-device high-overload test. The transient model yields a peak stress of 181.412 MPa in the sensitive structure. The reported drive and sense frequencies change from 7734.0 and 7755.7 Hz to 7745.2 and 7751.3 Hz, respectively, reducing the frequency split from 21.7 to 6.1 Hz. Under a calibrated impact of 16,190 g, the zero-rate output changes from 0.00178 to 0.06733°/s and the reported bias instability from 3.52 to 143.8°/h. A smaller frequency split therefore does not establish improved post-impact performance. For unchanged effective modal mass, the reported frequencies imply equivalent stiffness changes of approximately +0.290% and -0.113%. These estimates do not establish silicon plasticity or uniquely identify a package mechanism. The results are interpreted as a mechanism-oriented case study, with residual stress redistribution and boundary condition changes considered possible explanations requiring further physical verification. Population reliability and repeatability are outside the evidence provided by this single-device, single-event dataset.