An energetic approach for the experimental identification of damping in microstructures

The focus of this paper is the experimental measurement of damping in microstructures. The main source of damping in MEMS (micro electro-mechanical systems) is due to viscous dissipations of the surrounding fluid, although other dissipative effects are associated to internal frictions in the material, to surface and anchor losses, to parasitic currents, etc. The Kelvin-Voigt theory, normally used to describe the stress-strain relation in viscoelastic materials, also provides the estimation of the material damping capacity. In this work, the theory has been transferred from the continuum to the microstructural scale through integral approach, and an energetic method for computing the energy dissipations in the microscale is obtained. The adopted modeling approach estimates the effect of all damping contributions acting on the microstructure, including viscous damping of fluid and material damping. The validity of the experimental methodology based on the described theory is demonstrated by comparing the measured damping coefficients with those provided by two other experimental methods largely used in the microstructures characterization: the logarithmic response decay to step force and the half power method.