Structural vibration and acoustic radiation of coupled propeller-shafting and submarine hull system due to propeller forces

2017 ◽  
Vol 401 ◽  
pp. 76-93 ◽  
Author(s):  
Yegao Qu ◽  
Jinpeng Su ◽  
Hongxing Hua ◽  
Guang Meng
Keyword(s):  
Acoustic Radiation ◽  
Structural Vibration ◽  
Submarine Hull

FEM/BEM Simulation of Vibroacoustics of a Fluid-Loaded, Stiffened Plate Under Combined Force-Moment Excitation

2000 ◽  
Author(s):  
H. Zheng ◽  
C. Cai ◽  
G. R. Liu ◽  
K. Y. Lam
Keyword(s):  
Numerical Simulation ◽  
Acoustic Radiation ◽  
Normal Modes ◽  
Vibration Response ◽  
Structural Vibration ◽  
Stiffened Plate ◽  
Coupled Modes ◽  
Force Moment ◽  
Surrounding Fluid ◽  
Element Method

Abstract A numerical simulation of structural vibration and acoustic radiation is presented for a finite, fluid-loaded plate reinforced with two sets of orthotropic stiffeners. The attempt is to achieve a physical understanding of the dynamic behaviour and especially the acoustic radiation of the stiffened plate under combined force and moment excitations. Finite element method (FEM) is employed for calculation of the in-vacuo normal modes of the stiffened plate. The coupled modes with a heavy fluid (water), vibration response and acoustic radiation of the plate under given force and/or moment excitation are calculated using boundary element method (BEM). Numerical simulation results are detailed to address the significance of moment in combined force-moment excitations and, more importantly, the cancelling of the combined excitation in both structural vibration response and the associated acoustic radiation into the surrounding fluid.

Nonlinear Vibration Forces of Rotor-Bearing-Support System

2013 ◽  
Vol 437 ◽  
pp. 89-92
Author(s):  
Shu Yang ◽  
Qi Zheng Zhou ◽  
De Shi Wang
Keyword(s):  
Nonlinear Vibration ◽  
Support System ◽  
Vibration Analysis ◽  
Acoustic Radiation ◽  
Underwater Vehicle ◽  
Structural Vibration ◽  
Rotor Bearing ◽  
Rotary Speed ◽  
Numeral Simulation

The nonlinear vibration forces of rotor-bearing-supports system are important to the structural vibration and sound. Based on nonlinear vibration analysis of the system, the vibration equations were solved and the vibration forces were given by numeral simulation. The results show that the motions of forces are complex with the changing of rotary speed. The results could be used to determine the vibration and acoustic radiation of underwater vehicle under complex excitations.

A compact active structural acoustic control method for minimizing radiated sound power

2021 ◽  
Vol 263 (3) ◽  
pp. 3396-3406
Author(s):  
Scott Sommerfeldt
Keyword(s):  
Control Method ◽  
Acoustic Radiation ◽  
Structural Vibration ◽  
Sound Power ◽  
Flat Plates ◽  
Spatial Gradients ◽  
Acoustic Control ◽  
Radiated Sound ◽  
Radiated Sound Power ◽  
Structural Acoustic Control

Active structural acoustic control is an active control method that controls a vibrating structure in a manner that reduces the sound power radiated from the structure. Such methods focus on attenuating some metric that results in attenuated sound power, while not necessarily minimizing the structural vibration. The work reported here outlines the weighted sum of spatial gradients (WSSG) control metric as a method to attenuate structural radiation. The WSSG method utilizes a compact error sensor that is able to measure the acceleration and the acceleration gradients at the sensor location. These vibration signals are combined into the WSSG metric in a manner that is closely related to the radiated sound power, such that minimizing the WSSG also results in a minimization of the sound power. The connection between WSSG and acoustic radiation modes will be highlighted. Computational and experimental results for both flat plates and cylindrical shells will be presented, indicating that the WSSG method can achieve near optimal attenuation of the radiated sound power with a minimum number of sensors.

Quieting Plate Modes With Optimally Sized Point Masses: A Volume Velocity Approach

1995 ◽  
Author(s):  
Hans-Walter Wodtke ◽  
Gary H. Koopmann
Keyword(s):  
Acoustic Radiation ◽  
Sound Intensity ◽  
Structural Vibration ◽  
Acoustic Response ◽  
Radiation Problem ◽  
Volume Velocity ◽  
Intensity Measurements ◽  
Radiated Sound ◽  
The Masses ◽  
Radiated Sound Power

Abstract The radiated sound power of the second symmetric mode of a clamped square plate is minimized by attaching optimally sized point masses to the plate. The plate is driven by a point force at its center and the positions of the masses are prescribed. The structural vibration problem is solved using a simple Rayleigh-Ritz approach. Solving the acoustic radiation problem is simplified by making a low-ka-assumption, i.e., the point masses are determined so as to minimize the surface volume velocity of the plate. The predicted results are verified experimentally by means of sound intensity measurements. It is shown that a structural resonance can be deleted from the acoustic response by exploiting volume velocity cancellation. The effects involved are illustrated in detail.

Distributed Piezoelectric Actuators for Shell Interior Noise Control

1996 ◽  
Vol 118 (4) ◽  
pp. 676-681 ◽  
Author(s):  
J. Q. Sun ◽  
M. A. Norris ◽  
D. J. Rossetti ◽  
J. H. Highfill
Keyword(s):  
Control System ◽  
Structural Control ◽  
Acoustic Radiation ◽  
Control Strategies ◽  
Piezoelectric Actuators ◽  
Interior Noise ◽  
Theoretical Development ◽  
Structural Vibration ◽  
Control Approach ◽  
Wide Range

Structural controls have been recently used to reduce acoustic radiation from vibrating structures. It is well known that in some cases, a control system can reduce the noise and, at the same time, increase the structural vibration. This is one of the concerns with the structural control approach to solve the noise problem. Developing a control system that can reduce the noise and structural vibration at the same time is an important task. This paper proposes one of possible approaches for accomplishing this task. The emphasis of the present approach is not on control strategies, but rather on the design of distributed piezoelectric actuators for the structural control system. In the paper, we study the interior noise radiation and the structural vibrations of uniform cylindrical shells, which are taken as a simplified model of a fuselage section. Two distributed piezoelectric actuators are developed based upon the understanding of the structural-acoustic coupling properties of the system. These actuators can reduce the shell structural vibration and the interior noise at the same time in a wide range of frequencies by using only the acoustic error sensors. Hence, an optimal noise reduction is achieved. Computer simulations and the experiments have shown that the actuators can lead to global noise and vibration reduction. Excellent agreement between the analytical predictions and the experiments strongly supports the theoretical development.

Structural Excitation by a Turbulent Boundary Layer: An Overview

1988 ◽  
Vol 110 (2) ◽  
pp. 220-225 ◽  
Author(s):  
P. Leehey
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Power Flow ◽  
Acoustic Radiation ◽  
Practical Interest ◽  
Wall Pressure ◽  
Structural Vibration ◽  
Wave Number ◽  
Dense Fluid ◽  
Structural Excitation

Thirty years of theoretical and experimental research have yet to resolve a number of questions regarding the vibratory response of, and acoustic radiation from, a structure excited by a turbulent boundary layer (TBL). The most important questions are: (a) Can the TBL be characterized as a Thevenin source—particularly when vibratory power flow into the structure is maximized at hydrodynamic coincidence? Alternatively, at what level does structural vibration fundamentally change the character of the TBL? (b) Is the low wave number portion of the wall pressure spectrum of dominant importance in structural excitation away from hydrodynamic coincidence? Or do structural discontinuities cause the convective ridge of wall pressure to be of greater practical interest? (c) Can one quantify the radiation from a turbulent boundary layer about a rigid finite body? Is it dipole or quadrupole? What is the role of fluctuating wall shear stress? Current research on dense fluid loading and on modeling the behavior of the TBL is yielding new, and sometimes surprising, answers to some of these questions. Free resonant structural vibration in the dense fluid limit and the use of a bounded, non-causal, Green function representing the TBL are two of the surprises discussed.

Vibration Characteristics and Optimization of Variable Cross-Section Cylindrical Shell Structure under Multi-Point Excitation

2013 ◽  
Vol 372 ◽  
pp. 547-551
Author(s):  
Lin Chen ◽  
Xiao Zhong Xie ◽  
Zhuo Li ◽  
Fu Zhen Pang
Keyword(s):  
Cylindrical Shell ◽  
Cross Section ◽  
Shell Structure ◽  
Optimization Design ◽  
Acoustic Radiation ◽  
Variable Cross Section ◽  
Low Noise ◽  
Structural Vibration ◽  
Variable Cross ◽  
Transfer Path

According to the loading feature and the structure form, a gear reducer box can be simplified to a variable cross-section cylindrical shell structure excited by multipoint force. Meanwhile, a theoretical model is developed to analyze the structural vibration and acoustic characteristics and to find out the dominant component of vibration. Then, the influence of different parameters, such as, the local structure thickness, constrained damping layer and the insulation layer on acoustic radiation performance of the variable cross-section cylindrical shell structure are investigated by numerical calculation. Finally, an optimization design scheme of a low-noise structure is proposed because of the two aspects about noise source and noise transfer path.

Study on Vibration Modes and Acoustic Radiation Modes for Air Conditioning Compressor

2011 ◽  
Vol 141 ◽  
pp. 64-68
Author(s):  
Ming Yu ◽  
Ling Li Zhang ◽  
Yang Li ◽  
Xian Guo Yan ◽  
Juan Du
Keyword(s):  
Acoustic Signal ◽  
Air Conditioning ◽  
Acoustic Radiation ◽  
Indirect Measurement ◽  
Structural Vibration ◽  
Rotary Compressor ◽  
Vibration Modes ◽  
Acoustic Control ◽  
Analysis Theory ◽  
Radiation Behavior

Vibration and radiated sound of Air Conditioning are harmful to environment and safeness. Air Conditioning Compressor is its major part bringing vibration. To lower noise of a compressor and to improve its sound characteristic, the paper probes into a method indirect measurement of vibration, which both vibration and radiation behavior is represented using acoustic signal and theory of radiation modes. The paper investigates on the basic coupling relationship between structural vibration and acoustic radiation by means of the real modal analysis theory. Besides, the vibration and acoustic radiation characteristics of the rotary compressor are identified through the experiment method. According to the experimental results, between the vibration modes and the acoustic radiation modes have the comparability about the parameters. Therefore, this paper put forward a new method to the Active Structural Acoustic Control (ASAC), and provides the theoretical foundation of indirect measurement of vibration by using acoustic signal.

Investigation on vibration transmission control of a shafting system with active orthogonal support

2021 ◽  
pp. 107754632199358
Author(s):  
Yueyue Zhu ◽  
Xiling Xie ◽  
Zhiyi Zhang
Keyword(s):  
Control Method ◽  
Acoustic Radiation ◽  
Coupled System ◽  
Structural Vibration ◽  
Local Velocity ◽  
Electromagnetic Actuators ◽  
Vibration Transmission ◽  
Hull Structure ◽  
Dynamic Forces ◽  
Vibration And Sound Radiation

A large proportion of the fluctuating propulsion forces transmit to the hull structure of an underwater vehicle through the stern support and cause structural vibration and sound radiation. To reduce the influence of the dynamic forces on the hull structure, a control method that uses an active orthogonal support is proposed. The active orthogonal support is arranged in the vertical and horizontal directions to connect the stern bearing and the hull structure and equipped with electromagnetic actuators to generate counter forces. A shaft–hull-coupled system is used to investigate the effectiveness of active orthogonal support, and numerical results indicate that the hull vibration and acoustic radiation can be significantly suppressed. The effectiveness of active orthogonal support was experimented as well. The experimental results have demonstrated that the active orthogonal support with local velocity feedback control is able to attenuate vibration transmission in the shaft–hull-coupled system.

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