Nonlocal thermoelastic damping in microelectromechanical resonators

The evaluation of loss mechanisms in microscale mechanical resonators is addressed. Among various dissipation causes, thermoelastic loss is considered as a fundamental dissipation mechanism in microbeam resonators packed in a near-vacuum environment. However, the standard thermoelastic analysis is unable to interpret the size effect experimentally evidenced in resonators when the dimensions become very small, below several microns. In this paper we propose an enhanced nonlocal thermoelastic model, based on a thermodynamical formulation, which incorporates internal characteristic material lengths. Analytical results obtained with this nonlocal theory are compared with experimental results reported in the literature. It is shown how nonlocality can better interpret the observed behavior, at least in a certain range of resonators dimensions.