Predicting in-plane instability of high-speed rotating silicon multi-ring structures

Silicon multi-ring structures connected by spokes are ideal candidate to carry circumferential traveling waves in the design of MEMS vibratory gyroscope. However, these structures are prone to instability at high-speed rotation. This paper presents an efficient approach to determine the critical and flutter speeds of these structures for their various natural modes, and thereby to predict their in-plane instability. Through extensive parametric study, the effects of various design parameters on the instability of these structures are obtained and discussed. The results show that stability of these structures could be enhanced by increasing number of spokes, reducing number of rings, and reducing gaps between rings. Furthermore, it is found that these structures are more stable with circumferential traveling waves with a larger nodal diameter.