Active control of radiated sound power of a smart cylindrical shell based on radiation modes

2016 ◽  
Vol 114 ◽  
pp. 218-229 ◽  
Author(s):  
Ali Loghmani ◽  
Mohammad Danesh ◽  
Moon K. Kwak ◽  
Mehdi Keshmiri
Keyword(s):  
Cylindrical Shell ◽  
Active Control ◽  
Sound Power ◽  
Radiated Sound ◽  
Radiated Sound Power

Passive and Active Control of the Radiated Sound Power from a Submarine Excited by Propeller Forces

2013 ◽  
Vol 57 (1) ◽  
pp. 59-71 ◽  
Author(s):  
Sascha Merz ◽  
Nicole Kessissoglou ◽  
Roger Kinns ◽  
Steffen Marburg
Keyword(s):  
Active Control ◽  
Sound Power ◽  
Radiated Sound ◽  
Radiated Sound Power

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.

scholarly journals Investigation of Low-Frequency Sound Radiation Characteristics and Active Control Mechanism of a Finite Cylindrical Shell

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Shaohu Ding ◽  
Chunyang Mu ◽  
Yang Gao ◽  
Hong Liu ◽  
Maoqiang Li
Keyword(s):  
Cylindrical Shell ◽  
Active Control ◽  
Physical Mechanism ◽  
Sound Power ◽  
Radiation Characteristics ◽  
Low Frequencies ◽  
Acoustic Control ◽  
Radiated Sound ◽  
Finite Cylindrical Shell ◽  
Structural Acoustic Control

In this paper, the radiation characteristics and active structural acoustic control of a submerged cylindrical shell at low frequencies are investigated. First, the coupled vibro-acoustic equations for a submerged finite cylindrical shell are solved by a modal decomposition method, and the radiation impedance is obtained by the fast Fourier transform. The modal shapes of the first ten acoustic radiation modes and the structure-dependent radiation modes are presented. The relationships between the vibration modes and the radiation modes as well as the contributions of the radiation modes to the radiated sound power are given at low frequencies. Finally, active structural acoustic control of a submerged finite cylindrical shell is investigated by considering the fluid-structure coupled interactions. The physical mechanism of the active control is discussed based on the relationship between the vibration and radiation modes. The results showed that, at low frequencies, only the first several radiation modes contributed to the sound power radiated from a submerged finite cylindrical shell excited by a radial point force. By determining the radiation modes that dominate the contribution to the radiated sound, the physical mechanism of the active control is explained, providing a potential tool to allow active control of the vibro-acoustic responses of submerged structures more effectively.

A Study on Relevance between Distortion of Distributed Mode Loudspeaker and Characteristic of Sound Panel

2011 ◽  
Vol 291-294 ◽  
pp. 2105-2110
Author(s):  
Liang Jin Luo
Keyword(s):  
Vibration Frequency ◽  
Sandwich Panel ◽  
Flexural Vibration ◽  
Sound Power ◽  
Impedance Matrix ◽  
Cell Ratio ◽  
Radiated Sound ◽  
Sound Sensitivity ◽  
The Relationship ◽  
Radiated Sound Power

From flat-plate flexural vibration and radiated sound power discussed the inherent relationship between panel vibration frequency of distributed mode loudspeaker and geometric parameters, impedance matrix of soundboard and studied the relationship between soundboard structure of polyester foam sandwich panel and distortion of loudspeaker. Experimental results showed that distortion increases as the cell size and compress modulus, cell ratio, cell open ratio and thickness increases, but the sound sensitivity decreases as the compress modulus increases.

scholarly journals FE-BE computation of electromagnetic noise of a permanent-magnetic excited synchronous ma-chine considering dynamic rotor eccentricity

2018 ◽  
Vol 211 ◽  
pp. 18005
Author(s):  
Marcel Clappier ◽  
Lothar Gaul
Keyword(s):  
Sound Power ◽  
Fe Model ◽  
Electromagnetic Noise ◽  
Structural Dynamic ◽  
Magnetic Forces ◽  
Rotor Eccentricity ◽  
Resonance Frequencies ◽  
Radiated Sound ◽  
Run Up ◽  
Radiated Sound Power

Electromagnetic noise in Electrical Machines (EMs) occurs due to vibrations caused by magnetic forces acting onto rotor and stator surface. This is the dominant source for the considered permanent-magnetic excited synchronous machine in this paper. The radiated electromagnetic noise is sequentially calculated by a Finite Element (FE) and Boundary Element (BE) computation. An electromagnetic FE model is created to determine magnetic forces. Structure-borne sound and rotor dynamics are calculated using a structural dynamic FE model for the EM housing and the rotor. In order to predict resonance frequencies and amplitudes as reliable as possible, it is important to know the direction-dependent stiffness of the laminated rotor stacks and mechanical joints as well as their structural damping. Thereby, the properties of the laminated stack can be determined experimentally by a shear and dilatation test. Mechanical joint properties can be modelled by Thin-Layer Elements (TLEs) and the overall damping by the model of constant hysteretic damping. The radiated sound power is determined by a direct BE computation. The influence of dynamic rotor eccentricity on radiated sound power is examined for a run-up of the EM. All FE models are verified by data from experimental modal analysis.

Acoustic Radiation Simulation of Marine Sliding-Thrust Bearing Shell Based on SYSNOISE

2011 ◽  
Vol 291-294 ◽  
pp. 1961-1964
Author(s):  
Guang Liang Zhao
Keyword(s):  
Dynamic Analysis ◽  
Boundary Element ◽  
Thrust Bearing ◽  
Acoustic Radiation ◽  
Element Model ◽  
Sound Power ◽  
Supporting Structure ◽  
Radiated Sound ◽  
The Impact ◽  
Radiated Sound Power

This paper takes marine Kingsbury sliding thrust bearing as the research object and conducts the finite element dynamic analysis with the aid of ANSYS software. On this basis, the acoustic boundary element model of a sliding thrust bearing shell is established with the ANSYS dynamic analysis results as the boundary excitation conditions. Besides, the radiated sound power of the shell is calculated by indirect boundary element method in SYNOSISE software. The influence of different condition parameters on the radiated sound power of the shell is perceived through the analysis of several rotation-thrust conditions. As for the special structure of this kind of sliding-thrust bearing, this paper states the impact of the supporting structure performance parameters, the pad number and damp of shell on the shell radiated sound power. The optimized measure for the supporting structure and the plan concerning the pad number’s selection lays the theoretical basis for damping and noise-reducing research on marine sliding-thrust bearing and its rotor system.

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