Impacts of Length Scale Parameter on Material Dependent Thermoelastic Damping in Micro/nanoplates Applying Modified Coupled Stress Theory

Abstract

Among the different energy dissipation mechanisms, thermoelastic damping plays a vital role and need to
be alleviated in resonators inorder to enhance its performance parameters by improving its thermoelastic damping
limited qualityfactor, QTED. The maximum energy dissipation is also interrelated with critical length (???????? ) of the
plates and by optimizing the dimensions the peaking of energy dissipation can be diminished. As the size of the
devices is scaled down, classical continuum theories are not able to explain the size effect related mechanical
behavior at micron or submicron levels and as a result non-classical continuum theories are pioneered with the
inception of internal length scale parameters. In this paper, analysis of isotropic rectangular micro-plates based on
Kirchhoff model applying Modified Coupled Stress Theory is used toanalyzethe size-dependent thermoelastic
damping and its impact on quality factor and critical dimensions.Hamilton principle is adapted to derive the
governing equations of motion and the coupled heat conduction equation is employed to formulate the thermoelastic
damping limited quality factor of the plates. Five different structural materials (PolySi, Diamond,Si, GaAs and
SiC)are used for optimizing QTED which depends on the materialperformance index parameters. Thermoelastic
Damping Index [TDI] and thermal diffusion length, lT. According to this work, the maximum QTED is attained for
PolySi with the lowest TDI and Lcmax is obtained for SiC which is having the lowest lT. The impact of lengthscale
parameters (l), vibration modes, boundary conditions (Clamped–Clamped and Simply Supported), and operating
temperatures on QTED and Lcare also investigated. It is concluded that QTED is further maximized by selecting low
temperatures and higher internal length scale parameters (l).The prior knowledge of QTED and Lchelp the designers to
come out with high performance low loss resonators.