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.

scholarly journals Active control of structures and sound radiation modes and its application in vehicles

2016 ◽  
Vol 35 (4) ◽  
pp. 291-302 ◽  
Author(s):  
He-Xuan Hu ◽  
Bo Tang ◽  
Yang Zhao
Keyword(s):  
Radiation Power ◽  
Low Frequency ◽  
Sound Radiation ◽  
Diagonal Element ◽  
Structural Vibration ◽  
Structural Dynamic ◽  
First Order ◽  
Sound Radiation Efficiency ◽  
Sound Radiation Power ◽  
The Relationship

This paper presents computation of structural sound power and sound radiation modes, combined with structural dynamic equations to obtain the coupling relationship between sound and structures. As a result, the relationship between sound radiation modes of structures and structural vibration modes is established. The influence of the number and position of optimal secondary force sources on control of sound radiation modes is considered. Results show that sound radiation efficiency of sound radiation modes at the first order was more than that of sound radiation modes at other orders. The main diagonal element of coupling matrix between modes and sound radiation impedances was more than elements at other positions. Sound radiation modes at the first order were dominant sound radiation modes. When the number of secondary force sources was 4, the sound radiation power of structures was the lowest. Four force sources were taken as the basis to conduct on the related experiments in the anechoic chamber and compare with the computational result. Their results had a good consistency, which showed that the mentioned theory method was effective. Finally, the control strategy was applied to roofs of the vehicle. Experiments verified that sound pressure level of the driver in the low frequency was obviously improved, which remedied the defect of other optimization strategies for solving noises in the low frequency.

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.

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.

Acoustic Radiated Calculation of a Finite Cylindrical Shell and Interface Design of the Programs

2011 ◽  
Vol 378-379 ◽  
pp. 39-42
Author(s):  
Fei Fei Qiu ◽  
Xiao Wei Liu ◽  
Huan Wen Shi ◽  
Yong Wang
Keyword(s):  
Cylindrical Shell ◽  
Driving Force ◽  
Radiation Power ◽  
Cylindrical Shells ◽  
Sound Radiation ◽  
Sound Field ◽  
Directivity Pattern ◽  
Radiation Impedance ◽  
Simply Supported ◽  
Finite Cylindrical Shell

Based upon the vibratory equation and sound radiation impedance of a cylindrical shell, the sound field distribution of a finite cylindrical shell simply-supported at two infinite rigid cylindrical shells were resolved with considering the structural loss. An interface containing some buttons connected with all the programs was designed by using Matlab, and their data were all stored in a file. It has been shown that the sound radiation power of the cylindrical shell decreases and the radiation efficiency increases with increasing of structural damping loss factors; when the frequency of the driving force is low, the sound field shapes “∞” directivity pattern; When the frequency of the driving force grows higher the sound directivity pattern becomes complex due to superposition of axial modes and circumferential modes; Only when the radiation of the end plates is much weaker than the cylindrical shell the analytical results of the shell simply-supported at two infinite rigid cylindrical shells can be utilized to illustrate the sound radiation by a finite cylindrical shell with two end plates.

scholarly journals Faster Calculation of the Low-Frequency Radiated Sound Power of Underwater Slender Cylindrical Shells

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Rui Tang ◽  
He Tian ◽  
Dajing Shang
Keyword(s):  
Cylindrical Shell ◽  
Cylindrical Shells ◽  
Low Frequency ◽  
Sound Radiation ◽  
Sound Power ◽  
Radiation Characteristics ◽  
Calculation Process ◽  
Radiated Sound ◽  
Stiffened Cylindrical Shells ◽  
Radiated Sound Power

Based on the fact that beam-type modes play the main role in determining the sound radiation from an underwater thin slender (length-to-radius ratio L/a>20) elastic cylindrical shell, an equivalent-beam method is proposed for calculating the low-frequency radiated sound power of underwater thin slender unstiffened and stiffened cylindrical shells. The natural bending frequencies of the cylindrical shell are calculated by analytical and numerical methods and used to solve equivalent Young’s modulus of the equivalent beam. This approach simplifies the vibration problem of the three-dimensional cylindrical shell into that of a two-dimensional beam, which can be used to simplify the calculation process of radiated sound power. Added mass is used to approximate the fluid-structure coupling, further simplifying the calculation process. Calculation examples of underwater simply supported unstiffened and stiffened cylindrical shells verify the proposed method by comparison with analytical and numerical results. Finally, the effects of the size and spacing of the stiffeners on the sound radiation characteristics of underwater free-free stiffened cylindrical shells are discussed. The proposed method can be extended to the rapid calculation of the sound radiation characteristics of underwater slender complex cylindrical shells in the low-frequency range.

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