Sensors & Transducers (Dec 2019)
Analysis of Material Dependent Thermoelastic Damping Limited Critical Thickness in Micro/Nanobeams
Abstract
The thermoelastic energy dissipation of micro/nano beam resonators is a critical energy loss mechanism which limits the maximum attainable quality factor. Critical thickness of a resonator is defined as the thickness at which the peaking of energy takes place. The critical dimensions of the resonators are properly selected to alleviate the energy losses i.e. by properly selecting the thickness of the resonators the peaking of energy dissipation can be alleviated. Classical continuum theories cannot explain the size effect related to mechanical behavior at micron or submicron sizes. In this study, isotropic rectangular micro-plates are used to analyze the size-dependent thermoelastic damping and its impact on the critical thickness. Micro- and nanoplates using five different structural materials are analyzed to optimize hc, which depends on thermal diffusion length lT of the material. In our study, an expression for the theroelastic damping limited quality factor is obtained in terms of the material performance indices and simulated numerically. In this work, hcmax is obtained for resonators with Si material, which has the highest lT. The impact of length-scale parameters (l), vibration modes, boundary conditions, and operating temperatures on hc are also investigated. It is concluded that hc is maximized by selecting Si as the structural material with higher internal length-scale parameters (l). These results can help designers to engineer high-performance, low-loss resonators.
