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Mid-frequency vibration analysis of built-up structures

Mid-frequency vibration analysis of built-up structures
Mid-frequency vibration analysis of built-up structures

The thesis concerns the vibration analysis of built-up structures at frequencies where neither standard, low-frequency deterministic methods nor high-frequency statistical methods are appropriate, i.e. the so-called ‘mid-frequency’ vibration region.  The system model considered is a typical form of such complex built-up structures, composed of a long-wavelength (low mode-count) source and a short-wavelength (high mode-count) receiver. The interfaces might be either discrete-point couplings or continuous couplings.  The thesis is presented in four parts.

The first part concerns discrete point coupling cases between a stiff source and a flexible receiver. A concept of ‘power modes’ is introduced to estimate the power transmitted to a flexible receiver. It allows expressions for the upper and lower bounds and the mean value of the transmitted power to be developed in a simple manner.  The second part involves three cases of straight-line coupling of beam-stiffened plates. A hybrid Mode/FT approach and locally reacting impedance method are presented to predict simply and accurately the frequency response of the beam and the power transmitted to the plate, as well as the effective mass and damping loaded to the beam by the presence of the plate.  The third part concerns an arbitrary continuous coupling between the long- and short-wavelength substructures. A mode-based approach is described, which is able to accommodate both deterministic and statistical models. Relevant results are compared to those of ‘Resound’ and ‘Fuzzy’ structure theory. Following the numerical examples presented in the previous parts, the main theoretical developments are experimentally verified in Part IV. Good agreements are observed.

University of Southampton
Ji, Lin
ffbd69fc-52ea-4a83-be0e-bd9262031b24
Ji, Lin
ffbd69fc-52ea-4a83-be0e-bd9262031b24

Ji, Lin (2003) Mid-frequency vibration analysis of built-up structures. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The thesis concerns the vibration analysis of built-up structures at frequencies where neither standard, low-frequency deterministic methods nor high-frequency statistical methods are appropriate, i.e. the so-called ‘mid-frequency’ vibration region.  The system model considered is a typical form of such complex built-up structures, composed of a long-wavelength (low mode-count) source and a short-wavelength (high mode-count) receiver. The interfaces might be either discrete-point couplings or continuous couplings.  The thesis is presented in four parts.

The first part concerns discrete point coupling cases between a stiff source and a flexible receiver. A concept of ‘power modes’ is introduced to estimate the power transmitted to a flexible receiver. It allows expressions for the upper and lower bounds and the mean value of the transmitted power to be developed in a simple manner.  The second part involves three cases of straight-line coupling of beam-stiffened plates. A hybrid Mode/FT approach and locally reacting impedance method are presented to predict simply and accurately the frequency response of the beam and the power transmitted to the plate, as well as the effective mass and damping loaded to the beam by the presence of the plate.  The third part concerns an arbitrary continuous coupling between the long- and short-wavelength substructures. A mode-based approach is described, which is able to accommodate both deterministic and statistical models. Relevant results are compared to those of ‘Resound’ and ‘Fuzzy’ structure theory. Following the numerical examples presented in the previous parts, the main theoretical developments are experimentally verified in Part IV. Good agreements are observed.

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Published date: 2003

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Local EPrints ID: 465054
URI: http://eprints.soton.ac.uk/id/eprint/465054
PURE UUID: 416efef8-7108-44c6-8b72-c54bfa639833

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Date deposited: 05 Jul 2022 00:19
Last modified: 16 Mar 2024 19:55

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Author: Lin Ji

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