scholarly journals Analysis of the input power flow characteristics of cylindrical shells with combination boundaries

2018 ◽  
Vol 38 (1) ◽  
pp. 93-109
Author(s):  
Luyun Chen ◽  
Yong Liu
Keyword(s):  
Cylindrical Shell ◽  
Power Flow ◽  
Flow Characteristics ◽  
Rigid Wall ◽  
Input Power ◽  
Mirror Image ◽  
Image Method ◽  
Acoustic Space ◽  
Boundary Characteristics ◽  
Power Flow Problem

In this study, the input power flow problem of the cylindrical shell with complex acoustic boundaries was investigated. According to the acoustic characteristic of control domain which combination free interface and rigid wall interface at the same time for the cylindrical shell, the double reflection method and mirror image method were applied, and the analytical function of the input power flow for the cylindrical shell was derived. Finally, a cylindrical shell in the quarter-infinite acoustic space for example, the numerical calculation of input power flow of cylindrical shell was carried out. The influences of acoustic boundary characteristics, location, and frequency on the input power flow were compared. In addition, the effectiveness and convergence of the proposed method was verified using finite element method.

Vibrational Power Flow Analysis of Stiffened Plate and Shell Structures

2011 ◽  
Vol 66-68 ◽  
pp. 1897-1901 ◽  
Author(s):  
Xiang Zhu ◽  
Gong Yu Xiao ◽  
Tian Yun Li ◽  
Xiao Fang Hu
Keyword(s):  
Cylindrical Shell ◽  
Power Flow ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Input Power ◽  
Shell Structures ◽  
Stiffened Plate ◽  
Simply Supported ◽  
Plate And Shell ◽  
Flow Vectors

In this paper, the vibration and power flow characteristics of stiffened plate and cylindrical shell structures are investigated by using finite element method. The power flow formulas of basic shell structural elements are given at first. Then a simply supported plate and stiffened plate’s input power flow characteristics and power flow vectors are investigated. The effects of stiffeners in plates are discussed. For a simply supported cylindrical shell, the influence of the structural damping, viscous damper and stiffeners on the cylindrical shell’s input power flow characteristics and propagated power flow characteristics are discussed in detail. The power flow vectors are visualized to reveal the distribution of energy in the shell structures. Some useful conclusions are drown and helpful for the vibration control of plate and shell structures.

Vibration Power Flow Analysis of a Submerged Constrained Layer Damping Cylindrical Shell

2012 ◽  
Author(s):  
Yun Wang ◽  
Gangtie Zheng
Keyword(s):  
Cylindrical Shell ◽  
Power Flow ◽  
Axial Direction ◽  
Input Power ◽  
Exciting Force ◽  
Dynamic Equations ◽  
Constrained Layer Damping ◽  
Vibration Power Flow ◽  
Constrained Damping ◽  
Mode Order

The vibration power flow in a submerged infinite constrained layer damping (CLD) cylindrical shell is studied in the present paper using the wave propagation approach. Dynamic equations of the shell are derived with the Hamilton principle in conjunction with the Donnell shell assumptions. Besides, the pressure field in the fluid is described by the Helmholtz equation and the damping characteristics are considered with the complex modulus method. Then, the shell-fluid coupling dynamic equations are obtained by using the coupling between the shell and the fluid. Vibration power flows inputted to the coupled system and transmitted along the shell axial direction are both studied. Results show that input power flow varies with driving frequency and circumferential mode order, and the constrained damping layer will restrict the exciting force inputting power flow into the shell, especially for a thicker viscoelastic layer, a thicker or stiffer constraining layer (CL), and a higher circumferential mode order. Cut-off frequencies do not exist in the CLD cylindrical shell so that the exciting force can input power flow into the shell at any frequency and for any circumferential mode order. The power flow transmitted in the CLD cylindrical shell exhibits an exponential decay form along its axial direction, which indicates that the constrained damping layer has a good damping effect especially at middle or high frequencies.

The Vibro-Acoustic Characteristics of the Cylindrical Shell Partially Submerged in the Fluid

2012 ◽  
Vol 170-173 ◽  
pp. 2303-2311 ◽  
Author(s):  
Wen Bing Ye ◽  
Tian Yun Li ◽  
Xiang Zhu
Keyword(s):  
Cylindrical Shell ◽  
Free Surface ◽  
Power Flow ◽  
Sound Pressure ◽  
Harmonic Excitation ◽  
Input Power ◽  
Far Field ◽  
Fluid Coupling ◽  
Vibrational Power Flow ◽  
Field Sound

The characteristics of the sound radiation and vibrational power flow of the partially submerged cylindrical shell under a harmonic excitation are studied. The approximate acoustic boundary of the free surface is used to solve the fluid domain. The structure-fluid coupling equation is established based on the Flügge and Helmholtz theories. The far-field sound pressure is calculated and compared with that in infinite field. It is found that the far-field sound pressure presents large gap in different immersion status in the presence of the free surface while the results of the input power flow in these cases have less differences.

scholarly journals Vibration Power Flow of an Infinite Cylindrical Shell Submerged in Viscous Fluids

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Haosen Chen ◽  
Peng Yang ◽  
Yijun Shen
Keyword(s):  
Cylindrical Shell ◽  
Flow Field ◽  
Integral Method ◽  
Power Flow ◽  
Coupled System ◽  
Input Power ◽  
Wave Number ◽  
Acoustic Medium ◽  
Fluid Viscosity ◽  
Vibration Power Flow

In the previous investigations of the vibroacoustic characteristics of a submerged cylindrical shell in a flow field, the fluid viscosity was usually ignored. In this paper, the effect of fluid viscosity on the characteristics of vibration power flow in an infinite circular cylindrical shell immersed in a viscous acoustic medium is studied. Flügge’s thin shell theory for an isotropic, elastic, and thin cylindrical shell is employed to obtain the motion equations of the structure under circumferential-distributed line force. Together with the wave equations for the viscous flow field as well as continuity conditions at the interface, the vibroacoustic equation of motion in the coupled system is derived. Numerical analysis based on the additional-damping numerical integral method and ten-point Gaussian integral method is conducted to solve the vibroacoustic coupling equation with varying levels of viscosity. Then, the variation of the input power flow against the nondimensional axial wave number in the coupled system with different circumferential mode numbers is discussed in detail. It is found that the influence of fluid viscosity on the vibroacoustic coupled system is mainly concentrated in the low-frequency band, which is shown as the increase of the crest number and amplitude of the input power flow curves.

scholarly journals Study on Vibrational Power Flow Propagation Characteristics in a Laminated Composite Cylindrical Shell Filled with Fluid

2018 ◽  
Vol 2018 ◽  
pp. 1-19
Author(s):  
Jingxi Liu ◽  
Wentao He ◽  
De Xie
Keyword(s):  
Cylindrical Shell ◽  
Power Flow ◽  
Laminated Composite ◽  
Coupled System ◽  
Axial Direction ◽  
Input Power ◽  
Composite Cylindrical Shell ◽  
Internal Forces ◽  
Vibrational Power Flow ◽  
Flow Propagation

The characteristics of vibrational power flow in an infinite laminated composite cylindrical shell filled with fluid excited by a circumferential line cosine harmonic force are investigated using wave propagation approach. The harmonic motions of the shell and the fluid filled in the shell are described by Love shell theory and acoustic wave equation, respectively. Under the driving force, the vibrational power flow input into the coupled system and the transmission of the power flow carried by different internal forces (moments) of the shell in the axial direction are established. Numerical computations are implemented to investigate the vibrational power flow input and its propagation. It is found that characteristics of the vibrational power flow vary with different circumferential mode orders and frequencies, and the presence of fluid in the shell significantly affects the vibration of the shell structure. Additionally, parametric investigations are carried out to study the effects of the fiber orientation, modulus ratio E11/E22, and thickness-to-radius parameter h/R on input power into the coupled system and propagation power along the shell axial direction. This work will provide some guidance for the vibration control of the laminated composite cylindrical shell.

Active Control of Input Power Flow to the Cylindrical Shells Based on Piezoelectric Actuator

2013 ◽  
Vol 321-324 ◽  
pp. 1730-1743
Author(s):  
Tian Yun Li ◽  
Xu Wang ◽  
Xiang Zhu ◽  
Quan Zhou Jin
Keyword(s):  
Cylindrical Shell ◽  
Piezoelectric Actuator ◽  
Power Flow ◽  
Dynamic Models ◽  
Input Power ◽  
Control Effect ◽  
Total Input ◽  
Optimal Theory ◽  
Hermitian Quadratic Form ◽  
Infinite Cylindrical Shell

The dynamic models of the infinite cylindrical shell with integrated piezoelectric actuator are derived firstly in this paper, then, the total input power flow is calculated and expressed as the Hermitian quadratic form to act as the objective function to implement the control. The optimum set of secondary force is obtained by using feed-forward quadratic optimal theory, and the total input power flow with control was calculated for different locations of the actuator. The results show that different axial and circumferential locations will induce different influences on the control effect, and the results are greatly related to the vibration type and the circumferential mode.

Vibration Power Flow Analysis of a Submerged Constrained Layer Damping Cylindrical Shell

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Yun Wang ◽  
Gangtie Zheng
Keyword(s):  
Cylindrical Shell ◽  
Power Flow ◽  
Axial Direction ◽  
Input Power ◽  
Exciting Force ◽  
Dynamic Equations ◽  
Constrained Layer Damping ◽  
Vibration Power Flow ◽  
Constrained Damping ◽  
Mode Order

The vibration power flow in a submerged infinite constrained layer damping (CLD) cylindrical shell is studied in the present paper using the wave propagation approach. Dynamic equations of the shell are derived with the Hamilton principle in conjunction with the Donnell shell assumptions. Besides, the pressure field in the fluid is described by the Helmholtz equation and the damping characteristics are considered with the complex modulus method. Then, the shell-fluid coupling dynamic equations are obtained by using the coupling between the shell and the fluid. Vibration power flows inputted to the coupled system and transmitted along the shell axial direction are both studied. Results show that input power flow varies with driving frequency and circumferential mode order, and the constrained damping layer will restrict the exciting force inputting power flow into the shell, especially for a thicker viscoelastic layer, a thicker or stiffer constraining layer (CL), and a higher circumferential mode order. Cut-off frequencies do not exist in the CLD cylindrical shell, so that the exciting force can input power flow into the shell at any frequency and for any circumferential mode order. The power flow transmitted in the CLD cylindrical shell exhibits an exponential decay form along its axial direction, which indicates that the constrained damping layer has a good damping effect, especially at middle or high frequencies.

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