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Damping of plates with attached fluid or elastic layers

Damping of plates with attached fluid or elastic layers
Damping of plates with attached fluid or elastic layers
The thesis is in three parts. The first is a theoretical and experimental investigation of squeeze-film damping on plates separated by gas, for example. air. For this study a thick excited plate was attached to an auxiliary plate parallel to the surface, thereby trapping a thin layer of air. Relative vibration of these two plates pumps this air at high velocities, resulting in energy loss due to air viscosity. The theory employs an impedance approach to predict the loss factor of the coupled plates. Below the excited plate critical frequency the damping is controlled by gas pumping, while above the critical frequency the plate couplings are the controlling factor. Theoretical predictions were compared with experimental measurements. A brief examination of the bolting effect on the loss factor was also conducted. The second part is a theoretical and experimental investigation of squeeze-film damping on plates separated by heavy fluid, for example, oil. The attached plate can be either perforated or unperforated. The ratio of fluid dynamic viscosity to density controls the losses. Viscosity was artificially increased by inserting porous materials into the oil layer. The properties of the porous materials were obtained from macroscopic flow resistance measurements. Theoretical modelling of the loss factor of these layered configurations with oil alone and with oil impregnated porous material were conducted using the impedance approach and compared with experimental measurements. The third part is a theoretical and experimental investigation of granular infill damping treatments on plates. Sand was used in the experiments and the bulk and shear elastic constants were measured when the sand was subjected to varying hydrostatic pressures. Both the dilatational and rotational motions in the granular layer were considered and the loss factor predictions were compared with measured results.
Chow, Leung Choi
1b11d5cd-ba9f-4959-a646-b937e430ce62
Chow, Leung Choi
1b11d5cd-ba9f-4959-a646-b937e430ce62
Pinnington, R.J.
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Chow, Leung Choi (1987) Damping of plates with attached fluid or elastic layers. University of Southampton, Institute of Sound and Vibration Research, Doctoral Thesis, 275pp.

Record type: Thesis (Doctoral)

Abstract

The thesis is in three parts. The first is a theoretical and experimental investigation of squeeze-film damping on plates separated by gas, for example. air. For this study a thick excited plate was attached to an auxiliary plate parallel to the surface, thereby trapping a thin layer of air. Relative vibration of these two plates pumps this air at high velocities, resulting in energy loss due to air viscosity. The theory employs an impedance approach to predict the loss factor of the coupled plates. Below the excited plate critical frequency the damping is controlled by gas pumping, while above the critical frequency the plate couplings are the controlling factor. Theoretical predictions were compared with experimental measurements. A brief examination of the bolting effect on the loss factor was also conducted. The second part is a theoretical and experimental investigation of squeeze-film damping on plates separated by heavy fluid, for example, oil. The attached plate can be either perforated or unperforated. The ratio of fluid dynamic viscosity to density controls the losses. Viscosity was artificially increased by inserting porous materials into the oil layer. The properties of the porous materials were obtained from macroscopic flow resistance measurements. Theoretical modelling of the loss factor of these layered configurations with oil alone and with oil impregnated porous material were conducted using the impedance approach and compared with experimental measurements. The third part is a theoretical and experimental investigation of granular infill damping treatments on plates. Sand was used in the experiments and the bulk and shear elastic constants were measured when the sand was subjected to varying hydrostatic pressures. Both the dilatational and rotational motions in the granular layer were considered and the loss factor predictions were compared with measured results.

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Published date: February 1987
Organisations: University of Southampton

Identifiers

Local EPrints ID: 52269
URI: https://eprints.soton.ac.uk/id/eprint/52269
PURE UUID: 3e87b9c2-edc2-48d2-b545-d3947917bc5b

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Date deposited: 26 Aug 2008
Last modified: 13 Mar 2019 20:44

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Contributors

Author: Leung Choi Chow
Thesis advisor: R.J. Pinnington

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