Investigation of Thermoelastic Loss Mechanism in Shell Resonators

Maximizing quality (Q) factor is key to enhancing the performance of micro mechanical resonators, which are used in a wide range of applications such as gyroscopes, filters, and clocks. There are several energy loss mechanisms commonly associated with micro resonators including anchor loss through the substrate, squeeze film damping, thermoelastic dissipation (TED), and surface loss. This work focuses on the thermoelastic loss as one of the major energy dissipation mechanisms of micro shell resonators. In this article, the effects of material properties, thickness, conductive coating and operating temperature on the Q-factor of micro shell resonators are investigated. Numerical simulation shows shell resonators have higher Q-factors when they are operating at lower temperatures. Although, the magnitude of the simulated Q-factors of an uncoated bare resonator made from fused silica is more than 70 million and so it is too high to have a remarkable effect on the total Q-factor, our study shows that even a thin layer of some conductive coatings like gold on the surface of a bare shell reduces Q-factor significantly. The sensitivity of the coated shell resonator design to the TED phenomenon provides useful information for the development of new micro shell resonators with improved performance and Q-factors.