Analyse du comportement vibro-acoustique de structures immergées excitées par des sources transitoires

Abstract : In the sea, the acoustic detection of other battle engines is done by detecting mostly stationary signals. However, new types of detection systems are being developed, and are able to detect and to analyze transient signals. Therefore, the industrial conception process needs to be improved, so that the underwater vehicles transient noises can be taken in account. In order to do so, the mechanism of vibroacoustic transfer of transient sources of submerged structures has to be understood. The object of this thesis is then the study of the mechanism of vibration transfer and acoustic radiation of those structures when they are excited by transient sources. The shell radiation in the water, the wave diffraction by circumferential stiffeners and the resonant behavior of internal substructures are analyzed. The first chapter presents the bibliographical study of three themes: the study of transient phenomenon of submerged structures, the influence of heavy fluid coupling on vibroacoustic behavior of plates, and the different calculation methods in transient vibroacoustics. In the second chapter, we study the transient response of a submerged infinite plate excited by an impulsively point force. First, the calculations are done in the wavenumber-frequency domain. Then the spatio-temporal responses are obtained using inverse Fourier transforms. The discretization of wavenumber and frequency domains and the damping model are studied. The analysis of frequency and time responses of the plate vibration and the radiated pressure enable us to observe the influence of heavy fluid coupling. Besides the Mindlin-Timoshenko plate model is also used and the effect of rotation inertia and shear stress are studied. In the third chapter, these numerical results are confronted to experimental data, obtained experimentally. The studied structure is a rectangular plate lying on the surface of a water tank. Two different excitations are used: an impact hammer and the free fall of a steel ball. The study of the correlation between numerical and experimental results showed that some phenomena are observed in both cases. The influence of stiffeners on the acoustic radiation is the theme of the fourth chapter. An infinite plate which is periodically stiffened through one direction is considered. The effect of Bloch-Floquet waves on time response is studied. Numerical results are compared to measurements data obtained on an industrial submerged structure. In the fifth chapter, the effect of internal structures is analyzed by modelling an infinite plate coupled to a resonant system made of a beam and a rectangular finite plate. The inertance coupling method is used to obtain the coupling forces between the different substructures. Influence of inertance difference between the substructures is illustrated by the time signals.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-01247460
Contributor : Abes Star <>
Submitted on : Monday, January 4, 2016 - 3:10:56 PM
Last modification on : Saturday, May 18, 2019 - 3:34:23 AM
Long-term archiving on : Thursday, April 7, 2016 - 4:31:19 PM

File

these.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-01247460, version 1

Citation

Roch Scherrer. Analyse du comportement vibro-acoustique de structures immergées excitées par des sources transitoires. Acoustique [physics.class-ph]. INSA de Lyon, 2015. Français. ⟨NNT : 2015ISAL0037⟩. ⟨tel-01247460⟩

Share

Metrics

Record views

423

Files downloads

657