THE SOUND RADIATION EFFICIENCY OF FINITE LENGTH CIRCULAR CYLINDRICAL SHELLS UNDER MECHANICAL EXCITATION II: LIMITATIONS OF THE INFINITE LENGTH MODEL

2001 ◽  
Vol 241 (5) ◽  
pp. 825-838 ◽  
Author(s):  
C. WANG ◽  
J.C.S. LAI
Keyword(s):  
Finite Length ◽  
Cylindrical Shells ◽  
Sound Radiation ◽  
Radiation Efficiency ◽  
Infinite Length ◽  
Mechanical Excitation ◽  
Circular Cylindrical Shells ◽  
Sound Radiation Efficiency

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.

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.

Semi-Active Optimization of 2D Wave’s Dispersion Into Shunted Piezocomposite Systems for Controlling Acoustic Interaction

2011 ◽  
Author(s):  
Manuel Collet ◽  
Morvan Ouisse ◽  
Mohammed Ichchou ◽  
Roger Ohayon
Keyword(s):  
Brillouin Zone ◽  
Power Flow ◽  
Electrical Impedance ◽  
Sound Radiation ◽  
Numerical Approach ◽  
Radiation Efficiency ◽  
Bloch Theorem ◽  
Acoustic Interaction ◽  
Energy Diffusion ◽  
Sound Radiation Efficiency

In this paper, we present an application of the Floquet-Bloch theorem in the context of electrodynamics for vibroacoustic power flow optimization by mean of distributed and shunted piezoelectric patches. The main purpose of this work is first to propose a dedicated numerical approach able to compute the multi-modal wave dispersions curves into the whole first Brillouin zone for periodically distributed 2D shunted piezomechanical systems. By using two specific indicators evaluating the evanescent part of Bloch’s waves and the induced electronic damping, we optimize the piezoelectric shunting electrical impedance for controlling energy diffusion into the proposed semi-active distributed set of cells. Sound radiation efficiency is also analyzed for showing the effects of such smart metamaterial for controlling acoustical noise.

The Radiation of Sound from Mass-Loaded and Stiffened Beams

1985 ◽  
Vol 107 (1) ◽  
pp. 67-73 ◽  
Author(s):  
A. F. Seybert ◽  
P. J. Bowles
Keyword(s):  
Finite Element ◽  
Sound Radiation ◽  
Sound Field ◽  
Numerical Approach ◽  
Radiation Efficiency ◽  
Uniform Beam ◽  
Vibration Model ◽  
Vibrating Beams ◽  
Radiated Sound ◽  
Sound Radiation Efficiency

This study examines the sound radiation efficiency of uniform, mass-loaded, and stiffened beams. The radiation efficiency of vibrating beams is determined using a finite element vibration model of the beam and a numerical approach to determine the radiated sound field. The radiation efficiency of mass-loaded and stiffened beams deviates from that of the uniform beam for frequencies near and below coincidence. The radiation efficiency of the nonuniform beams depends on the change in natural frequency and the distortion of the mode shape of the vibrating beam. Near coincidence, the radiation efficiency of nonuniform beams approaches that of the uniform beam. Above coincidence, all beams exhibit a radiation efficiency of unity.

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