Influence of Acoustic Coating on the Underwater Sound Radiation of a Double Hull Cylindrical Shell Structure

2011 ◽  
Vol 338 ◽  
pp. 406-410
Author(s):  
Fu Zhen Pang ◽  
Fu Bin Pang ◽  
Xu Chao Yin ◽  
Shuai Lv
Keyword(s):  
Cylindrical Shell ◽  
Noise Reduction ◽  
Shell Structure ◽  
Sound Radiation ◽  
Radiation Characteristic ◽  
Underwater Sound ◽  
Surrounding Water ◽  
Covering Density ◽  
Hull Structure ◽  
Double Hull

This paper studies the influence of acoustic coating to the underwater sound radiation characteristic of a double hull cylindrical shell by the Statistical Energy Analysis (SEA) method. Influence of covering density and laying location of acoustic coating to the underwater sound radiation characteristic of the double hull cylindrical shell structure are discussed. Study shows that low covering density of acoustic coating will cause “sound leaking” phenomena, sound will leak out from the uncovered area of the double hull cylindrical hull structure and radiate into the surrounding water, which harms the underwater noise reduction performance of the acoustic coating; however, the noise reduction capacity of the acoustic coating improves gradually as the covering density increases. Besides, laying location of acoustic coating also impact the underwater sound radiation performance of the double hull cylindrical shell structure; inner hull covered with acoustic coating is better than the outer hull covered from the noise treatment point of view

Research on Vibration and Sound Radiation from Submarine Functionally Graded Material Nonpressure Cylindrical Shell

2013 ◽  
Vol 690-693 ◽  
pp. 3046-3049
Author(s):  
Yan Bing Zhang ◽  
Chun Yu Ren ◽  
Xi Zhu
Keyword(s):  
Cylindrical Shell ◽  
Acoustic Radiation ◽  
Radiation Power ◽  
Sound Radiation ◽  
Functionally Graded ◽  
Underwater Sound ◽  
Graded Materials ◽  
Graded Material ◽  
Vibration And Sound Radiation ◽  
Sound Radiation Power

In this paper, we establish the finite element (FEM) and boundary element (BEM) models of a submarine section, and study the underwater sound radiation field of three different non-pressure shells made of steel, steel with anechoic tile, and the functionally graded materials (FGM) separately using a method combining of FEM and BEM . Research shows that the combination of FEM and BEM can address the acoustic radiation calculation problem of FGM, and in comparison with steel and anechoic tile laying submarine section, the weight of FGM non-pressure shell reduces 1600kg, and the sound radiation power decreases 4db and 2.5db respectively, thus having better performance in vibration and noise reduction.

Multi-channel Active Vibration Isolation for the Control of Underwater Sound Radiation From A Stiffened Cylindrical Structure: A Numerical Study

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Huang Xiuchang ◽  
Zhang Zhiyi ◽  
Zhang Zhenhua ◽  
Hua Hongxing
Keyword(s):  
Cylindrical Shell ◽  
Vibration Isolation ◽  
Sound Radiation ◽  
Spatial Average ◽  
Far Field ◽  
Underwater Sound ◽  
Cylindrical Structure ◽  
Vibration Isolators ◽  
Active Vibration ◽  
Active Vibration Isolation

Numerical simulation of vibration control of a submerged stiffened cylindrical structure with active vibration isolators is presented. Vibration transmission from vibrating machinery to the cylindrical structure through the active vibration isolators is analyzed by a numerical model synthesized from frequency response functions (FRFs) and impedances. The coupled finite element/boundary element (FE/BE) method is employed to study the vibro-acoustic behavior of the fluid-loaded cylindrical structure. Sound pressure in the far-field is calculated in terms of the pressure and normal acceleration of the outer surface of the cylindrical shell. An adaptive multichannel control based on the filtered-x least mean squares (FxLMS) algorithm is used in the active vibration isolation. Simulation results have demonstrated that suppression of vibration of the four elastic foundations attached to the cylindrical shell will reduce the spatial-average mean-square velocity and the instantaneous radiated power of the cylindrical shell. As a result, suppression of vibration of the foundations leads to attenuation of sound radiation in the far-field induced by the radial displacement dominant mode of the shell. Moreover, vibration suppression is greatly influenced by the strong couplings among control channels. According to these results, it can be concluded that the proposed method is effective in the analysis of underwater sound radiation control of cylindrical structures.

202,500 DWT Open Hatch Type Double Hull Structure Bulk Carrier

2009 ◽  
Author(s):  
H L Chien ◽  
◽  
C M Chou ◽  
K T Tsai ◽  
K C Tseng ◽  
...  
Keyword(s):  
Bulk Carrier ◽  
Hull Structure ◽  
Double Hull

Influence of Internal Structures of High Modal Density on Shell’s Radiation

1997 ◽  
Author(s):  
Lionel Oddo ◽  
Bernard Laulagnet ◽  
Jean-louis Guyader
Keyword(s):  
Cylindrical Shell ◽  
Sound Radiation ◽  
Numerical Results ◽  
Structural Damping ◽  
Radiation Spectra ◽  
Modal Density ◽  
Internal Structures ◽  
High Modal Density

Abstract The aim of this paper is to study the sound radiation by a cylindrical shell internally coupled with mechanical structures of high modal density. The model is based on a mobility technique. The numerical results show a smoothing of the cylinder’s velocity and radiation spectra associated with an increase of the apparent damping. The use of the S.E.A. method allows us to calculate an additional structural damping of the shell, equivalent to the effect of the internal structures.

Measured Imperfections and Their Effects on Strength of Component Plates of a Prototype Double Hull Structure

1995 ◽  
Vol 11 (01) ◽  
pp. 47-52
Author(s):  
Alan AhKum Pang ◽  
Robert Tiberi ◽  
Le-Wu Lu ◽  
James Ricles ◽  
Robert Dexter
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
The Finite Element Method ◽  
Initial Imperfections ◽  
Hsla Steels ◽  
Hull Structure ◽  
Surface Combatant ◽  
Double Hull ◽  
The U.S ◽  
Compressive Tests

The U.S. Navy is currently studying the use of double hull designs in high strength low alloy (HSLA) steels for surface combatant ships. A full-scale prototype double hull module was fabricated, from which multicellular box column specimens were cut for compressive tests to failure. Initial imperfections, i.e., initial plate deflections and welding residual stresses, affect the stiffness and strength of welded members. This paper describes the measurement of these imperfections and the analysis of their effects on the component plates of the cellular box specimens. Initial deflections were measured in the laboratory, where the maximum values did not exceed the Navy's guidelines or proposed values of several researchers. Residual stresses in a box specimen were also measured in the laboratory under more controlled conditions. Using the measured imperfections, the plate arrangements were analyzed using the finite element method. The imperfections were found to reduce the stiffness and strength of the plates. The results show that for accurate prediction of the strength of welded plates, initial imperfections must be taken into account.

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