Mechanism And Model Of Thermoelastic Damping In Microbeam Resonators With Rhombic Cross-Section

Micro-mechanical resonant device is a new type of resonant devices in recent years. Quality factor is the core parameter of this kind of device. It is a measure of the amount of energy stored in the system compared to the energy dissipated over a period of time. A higher quality factor means lower energy dissipation, increased sensitivity and improved stability for the system. Generally speaking, damping in Micro-Electro-Mechanical Systems (MEMS) resonators arises from two principal sources, namely external energy dissipation and intrinsic energy dissipation. The external dissipation mechanism includes air damping, anchor damping and surface loss. External dissipations can be removed by appropriate design and working conditions. Thermoelastic damping is an internal energy dissipation mechanism in MEMS, and it cannot be controlled as easily as external dissipation mechanisms. As the inherent property of materials, TED does not only restrict the quality factor's maximum of resonators, but also have great influence on their sensitivity, resolution, noise characteristic and so on. For this reason, thermoelastic damping in flexures has been an active area of current theoretical research for a long time.It is of great value to develop more specific TED model. For the rectangle and the circular cross-section microbeam resonators, the research of TED has been mature. But the TED in the microbeams with rhombus cross-section has not yet been studied. This paper purposes to study the mechanism and model of TED in microbeam resonators with rhombic cross-section. Detailed formulas are derived, for the first time, based on the previous research. In the latter part of this paper, the theoretical models are summarized and analyzed on adiabatic thermal boundary conditions. In order to observe the results visually, they are transformed into a curve form using MATLAB software. We obtain that the quality factor will be increased when microbeams of rhombus cross-section is operated in high frequency state (>109rad·s-1). At last, the Finite Element Method (FEM) is used to calculate the TED by ANSYS. Through comparing theoretical results with numerical simulation of finite element theory, the analytical model of this paper is proved to be valid and feasible under certain situation. It can provide an effective theoretical basis for quickly and accurately estimating the TED in microbeam resonators with rhombic cross-section.