Sound radiation from finite cylindrical shells, partially covered with longitudinal strips of compliant layer

1995 ◽  
Vol 186 (5) ◽  
pp. 723-742 ◽  
Author(s):  
B. Laulagnet ◽  
J.L. Guyader
Keyword(s):  
Cylindrical Shells ◽  
Sound Radiation ◽  
Compliant Layer

Characteristics of Modal Sound Radiation of Finite Cylindrical Shells

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Tian Ran Lin ◽  
Chris Mechefske ◽  
Peter O’Shea
Keyword(s):  
Cylindrical Shells ◽  
Low Frequency ◽  
Sound Radiation ◽  
Sound Field ◽  
Radiation Efficiency ◽  
Boundary Element Methods ◽  
Frequency Range ◽  
Nodal Lines ◽  
Infinite Cylindrical Shell ◽  
Modal Index

Characteristics of modal sound radiation of finite cylindrical shells are studied using finite element and boundary element methods in this paper. In the low frequency range, modal radiation efficiencies of finite cylindrical shells are found to asymptotically approach those of the corresponding infinite cylindrical shell when structural trace wavelengths of the cylindrical shells are greater than the acoustic wavelength. Modal radiation efficiencies for each group of modes having the same circumferential modal index decrease as the axial modal index increases. They converge to each other when the axial trace wavelength is much greater than the circumferential trace wavelength. The mechanism leading to lower radiation efficiency of modes with higher circumferential modal index of short cylinders is explained. Similar to those of flat plate panels, change in slope or waviness is observed in modal radiation efficiency curves of modes with higher order axial modal index at medium frequencies. This is attributed to the interference of sound radiated by neighboring vibrating cells when the distance between nodal lines of a vibrating mode is in the same order or smaller than the acoustic wavelength. The effects of the internal sound field on modal radiation efficiencies of a finite open-end cylinder are discussed.

Simulation of Vibration and Acoustic Radiation of Finite Underwater Cylindrical Shells

2000 ◽  
Author(s):  
X. M. Zhang ◽  
G. R. Liu ◽  
K. Y. Lam
Keyword(s):  
Acoustic Analysis ◽  
Acoustic Radiation ◽  
Cylindrical Shells ◽  
Sound Radiation ◽  
Coupled Vibration ◽  
Response Curves ◽  
Vibration And Sound Radiation ◽  
Acoustic Domain ◽  
High Sound ◽  
Element Method

Abstract A coupled structural-acoustic analysis of vibration and sound radiation of underwater finite cylindrical shells is investigated in this paper. The coupled vibration and radiation problem is formulated using Finite Element Method (FEM) for the structure and Boundary Element Method (BEM) for the acoustic domain. Vibration and sound radiation under symmetrical and unsymmetrical point force excitations are examined. It is shown that the coupled modals are the causes of large vibration of the shell and high sound pressure radiation of the acoustic fields. The shapes of frequency response curves of pressure are quite similar in the far fields but change greatly in the near fields.

scholarly journals Prediction of Sound Radiation from Submerged Cylindrical Shell Based on Dominant Modes

2020 ◽  
Vol 10 (9) ◽  
pp. 3073 ◽  
Author(s):  
Chao Zhang ◽  
Sihui Li ◽  
Dejiang Shang ◽  
Yuyuan Han ◽  
Yuyang Shang
Keyword(s):  
Cylindrical Shell ◽  
Radiation Power ◽  
Cylindrical Shells ◽  
Low Frequency ◽  
Sound Radiation ◽  
Radiation Efficiency ◽  
Frequency Sound ◽  
Comparison Results ◽  
Sound Radiation Efficiency ◽  
Sound Radiation Power

A sound radiation calculation method by using dominant modes is proposed to predict the sound radiation from a cylindrical shell. This method can provide an effective way to quickly predict the sound radiation of the structure by using as few displacement monitoring points as possible on the structure surface. In this paper, modal analyses of a submerged cylindrical shell are carried out by taking the vibration mode of a cylindrical shell in a vacuum, as a set of orthogonal bases. The modal sound radiation efficiency and modal contributions to sound radiation power are presented, and comparison results show that a few modes dominantly contribute to the sound radiation power at low frequencies. These modes, called dominantly radiated structural modes in this paper, are applied to predict the sound radiation power of submerged cylindrical shells by obtaining the modal participant coefficients and sound radiation efficiency of these dominant modes. Aside from the orthogonal decomposition method, a method of solving displacement modal superposition equations is proposed to extract the modal participant coefficients, because few modes contribute to the vibration displacement near the resonant frequencies. Some simulations of cylindrical shells with different boundaries are conducted, and the number of measuring points required are examined. Results show that this method, based on dominant modes, can well predict the low-frequency sound radiation power of submerged cylindrical shells. In addition, compared with the boundary element method, this method can better reduce the number of required measuring points significantly. The data of these important modes can be saved, which can help to predict the low-frequency sound radiation of the same structure faster in the future.

Sound Radiation From a Finite Cylindrical Shell Covered With a Compliant Layer

1991 ◽  
Vol 113 (2) ◽  
pp. 267-272 ◽  
Author(s):  
B. Laulagnet ◽  
J. L. Guyader
Keyword(s):  
Cylindrical Shell ◽  
Frequency Domain ◽  
Mathematical Analysis ◽  
Strong Influence ◽  
Sound Radiation ◽  
Radiated Power ◽  
Shell Motion ◽  
Compliant Layer ◽  
Finite Cylindrical Shell ◽  
Large Frequency

The aim of this work is to present the mathematical analysis and numerical results about sound radiation from a finite cylindrical shell covered with a compliant layer, immersed in water. The shell motion is obtained using Flu¨gge’s operator whereas the layer is described by a locally reacting material. The results are presented both in shell radial quadratic velocity and radiated power. Two major conclusions can be drawn when looking at results: (1) a reasonable stiffness layer allows one to reduce the radiated power in a large frequency domain; (2) the layer has a strong influence on the shell velocity which exhibits an antiresonance phenomenon when covered.

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