Thermalizing and Damping in Structural Dynamics
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jam_085_08_081001.pdf
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1.8 MB
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Author(s)
Louhghalam, Arghavan
Pellenq, Roland Jm
Ulm, Franz-Josef
Date Issued
May 2018
Journal
Journal of Applied Mechanics
Publisher
ASME International
Citation
Louhghalam, Arghavan, et al. “Thermalizing and Damping in Structural Dynamics.” Journal of Applied Mechanics, vol. 85, no. 8, May 2018, p. 081001. © 2018 by ASME.
Version
Final published version
Abstract
Structural damping, that is the presence of a velocity dependent dissipative term in the equation of motion, is rationalized as a thermalization process between a structure (here a beam) and an outside bath (understood in a broad sense as a system property). This is achieved via the introduction of the kinetic temperature of structures and formalized by means of an extended Lagrangian formulation of a structure in contact with an outside bath at a given temperature. Using the Nosé-Hoover thermostat, the heat exchange rate between structure and bath is identified as a mass damping coefficient, which evolves in time in function of the kinetic energy/temperature history exhibited by the structure. By way of application to a simple beam structure subjected to eigen-vibrations and dynamic buckling, commonality and differences of the Nosé-Hoover beam theory with constant mass damping models are shown, which permit a handshake between classical damping models and statistical mechanics-based thermalization models. The solid foundation of these thermalization models in statistical physics provides new insights into stability and instability for engineering structures. Specifically, since two systems are considered in (thermodynamic) equilibrium when they have the same temperature, we show in the case of dynamic buckling that a persistent steady-state difference in kinetic temperature between structure and bath is but indicative of the instability of the system. This shows that the kinetic temperature can serve as a structural order parameter to identify and comprehend failure of structures, possibly well beyond the elastic stability considered here. Keywords: structural dynamics, damping, Nose–Hoover Bath, kinetic temperature, dynamic buckling
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1115/1.4040080
