Energy Dissipation In Resonators Research Articles

Thermoelastic Damping in Fully Clamped Circular Plate Resonators Based on Nonlocal Thermoelasticity

Thermoelastic damping (TED) is the main source of energy dissipation in resonators. The modelling of TED is of great importance for the design of micro-electro-mechanical systems (MEMS) and the improvement of quality factor. Most of the previous TED models are based on classical continuum mechanics and Fourier heat conductive model. However, small-scale effects are widely found for structures at nano and sub-micron level and the classical theories cannot describe their size-dependent behaviors. Based on the nonlocal elasticity theory and the nonlocal heat conductive model, the thermoelastic coupled governing equations of a circular plate with out-of-plane vibration under the influence of nonlocal effect are derived in this paper. The influences of nonlocal thermoelasticity on TED in circular plates are discussed by numerical examples under different boundary conditions, frequencies, thicknesses and modes.

Energy Dissipation in Graphene Mechanical Resonators with and without Free Edges.

Graphene-based nanoelectromechanical systems (NEMS) have high future potential to realize sensitive mass and force sensors owing to graphene’s low mass density and exceptional mechanical properties. One of the important remaining issues in this field is how to achieve mechanical resonators with a high quality factor (Q). Energy dissipation in resonators decreases Q, and suppressing it is the key to realizing sensitive sensors. In this article, we review our recent work on energy dissipation in doubly-clamped and circular drumhead graphene resonators. We examined the temperature (T) dependence of the inverse of a quality factor () to reveal what the dominant dissipation mechanism is. Our doubly-clamped trilayer resonators show a characteristic -T curve similar to that observed in monolayer resonators: ∝ above ∼100 K and ∝ below ∼100 K. By comparing our results with previous experimental and theoretical results, we determine that the and dependences can be attributed to tensile strain induced by clamping metals and vibrations at the free edges in doubly-clamped resonators, respectively. The -T curve in our circular drumhead resonators indicates that removing free edges and clamping metal suppresses energy dissipation in the resonators, resulting in a linear T dependence of in a wide temperature range.

Structuring of Inorganic Materials in Weak RF Electromagnetic Fields

Data are presented on the effect of weak rf electromagnetic fields on the setting of mineral binders and crystallization of metals, alloys, solutions, and molten salts. The results are interpreted in terms of electromagnetoacoustic conversion. The assumption is made that resonance energy dissipation gives rise to coupled motions of fluctuating supramolecular structures in the mesophase, thereby increasing the transport rate and leveling off the thermodynamic parameters of the system.