Acoustic and Vibration Characteristics of Finite Cylindrical Shell-Circular Plate Based on Lagrange Equations

2013 ◽  
Vol 302 ◽  
pp. 401-405
Author(s):  
Qi Zheng Zhou ◽  
De Shi Wang ◽  
Shu Yang
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Circular Plate ◽  
Acoustic Radiation ◽  
Vibration Characteristics ◽  
Finite Cylinder ◽  
Lagrange Equations ◽  
Coupling Conditions ◽  
Set Up ◽  
Finite Cylindrical Shell

An analysis based on Lagrange equations was presented for acoustic and vibration characteristics of finite cylindrical shell-circular plate underwater. The boundary conditions and coupling conditions between the shell and plate expressed using springs, the model of finite shell with circular plate was set up. Considering the elastic potential energy in springs and the work due to fluid loading, the vibro-acoustic equations of finite cylinder with circular plate under excitation were established by Lagrange equations. The influences of boundary conditions and coupling conditions to the acoustic and vibration characteristics were researched. The results show that . The results could be used to control the underwater vehicle’s vibration and acoustic radiation.

Vibrational and acoustic radiation from a submerged periodic cylindrical shell with axial stiffening

2009 ◽  
Vol 223 (5) ◽  
pp. 1083-1089 ◽  
Author(s):  
C-J Liao ◽  
W-K Jiang ◽  
H Duan ◽  
Y Wang
Keyword(s):  
Cylindrical Shell ◽  
Analytical Study ◽  
Acoustic Radiation ◽  
Sound Radiation ◽  
Mechanical Impedance ◽  
Stiffened Cylindrical Shell ◽  
Reaction Forces ◽  
Radial Forces ◽  
Vibration And Sound Radiation ◽  
Finite Cylindrical Shell

An analytical study on the vibration and acoustic radiation from an axially stiffened cylindrical shell in water is presented. Supposing that the axial stiffeners interact with the cylindrical shell only through radial forces, the reaction forces on the shell from stiffeners can be expressed by additional impedance. The coupled vibration equation of the finite cylindrical shell with axial stiffening is derived; in this equation additional impedance caused by the axial stiffeners is added. As a result, the vibration and sound radiation of the shell are dependent on the mechanical impedance of the shell, the radiation sound impedance, and the additional impedance of the axial stiffeners. Based on the numerical simulation, it is found that the existence of axial stiffeners decreases the sound radiation and surface average velocity, whereas it increases the radiation factor. The characteristics of the acoustic radiation can be understood from the simulation with good results, which show that the presented methodology can be used to study the mechanism of the acoustic radiation of the complicated cylindrical shell and to optimize its design.

Research on Vibro-Acoustic Characteristics of Underwater Finite Plate-Shell Structure under Multiple Excitations

2013 ◽  
Vol 834-836 ◽  
pp. 1351-1359
Author(s):  
Yong Yong Zhu
Keyword(s):  
Shell Structure ◽  
Acoustic Radiation ◽  
Radiation Power ◽  
Acoustic Vibration ◽  
Finite Cylinder ◽  
Acoustic Characteristics ◽  
Theory Of Plates ◽  
Plates And Shells ◽  
Vibration Coupling ◽  
Finite Cylindrical Shell

An analysis based on the first kind of Lagranges equations was presented for investigating the vibration and acoustic radiation of underwater finite cylindrical shell with interior plate under multiple excitations. The strain energy and kinetic energy of cylinder and plate were gained by the theory of plates and shells, and the potential energy of excitation and fluid loading was found based on acoustic-vibration coupling, and the connection conditions of plate and cylinder were expressed by Lagrange multipliers, then the vibro-acoustic equations of finite cylinder with interior plate under shafting excitation were established. The influences of excitations and plates position to the vibro-acoustic characteristics were studied by the equations. The results show that the frequency components of plate-shell structure are more complex. For the double excitations on plate, the distance between excitations is larger, the average velocity and sound radiation power are lower, while the radiation efficiency is larger. The modeling and analytical methods adopted in this paper are also available for more complex composite structure.

scholarly journals Wave Based Method for Free Vibration Analysis of Ring Stiffened Cylindrical Shell with Intermediate Large Frame Ribs

2013 ◽  
Vol 20 (3) ◽  
pp. 459-479 ◽  
Author(s):  
Meixia Chen ◽  
Jianhui Wei ◽  
Kun Xie ◽  
Naiqi Deng ◽  
Guoxiang Hou
Keyword(s):  
Cylindrical Shell ◽  
Free Vibration ◽  
Boundary Conditions ◽  
Natural Frequencies ◽  
Free Vibration Analysis ◽  
Structure Type ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Arbitrary Boundary ◽  
Stiffened Cylindrical Shell

Wave based method which can be recognized as a semi-analytical and semi-numerical method is presented to analyze the free vibration characteristics of ring stiffened cylindrical shell with intermediate large frame ribs for arbitrary boundary conditions. According to the structure type and the positions of discontinuities, the model is divided into different substructures whose vibration field is expanded by wave functions which are exactly analytical solutions to the governing equations of the motions of corresponding structure type. Boundary conditions and continuity equations between different substructures are used to form the final matrix to be solved. Natural frequencies and vibration mode shapes are calculated by wave based method and the results show good agreement with finite element method for clamped-clamped, shear diaphragm – shear diaphragm and free-free boundary conditions. Free vibration characteristics of ring stiffened cylindrical shells with intermediate large frame ribs are compared with those with bulkheads and those with all ordinary ribs. Effects of the size, the number and the distribution of intermediate large frame rib are investigated. The frame rib which is large enough is playing a role as bulkhead, which can be considered imposing simply supported and clamped constraints at one end of the cabin and dividing the cylindrical shell into several cabins vibrating separately at their own natural frequencies.

Influence of Boundary Conditions on the Active Control of Vibration and Sound Radiation for a Circular Cylindrical Shell

2011 ◽  
Vol 66-68 ◽  
pp. 1270-1277
Author(s):  
Lu Dai ◽  
Tie Jun Yang ◽  
Yao Sun ◽  
Ji Xin Liu
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Active Control ◽  
Structural Engineering ◽  
Acoustic Radiation ◽  
Circular Cylindrical Shell ◽  
Acoustic Power ◽  
Fourier Series Method ◽  
Vibration And Sound Radiation ◽  
Elastically Restrained

Vibration and acoustic radiation of circular cylindrical shells are hot topics in the structural engineering field. However for a long period, this sort of problems is only limit to classical homogeneous boundary conditions. In this paper, the vibration of a circular cylindrical shell with elastic boundary supports is studied using modified Fourier series method, and the far-field pressure for a baffled shell is calculated by Helmholtz integral equation. Active control of vibration and acoustic radiation are carried out by minimizing structural kinetic energy and radiated acoustic power respectively. The influence of boundary conditions on the active control is investigated throughout several numerical examples. It is shown that the active control of vibration and acoustic for an elastically restrained shell can exhibit unexpected and complicated behaviors.

scholarly journals Vibration Characteristics Analysis of Cylindrical Shell-Plate Coupled Structure Using an Improved Fourier Series Method

2018 ◽  
Vol 2018 ◽  
pp. 1-19 ◽  
Author(s):  
Yipeng Cao ◽  
Runze Zhang ◽  
Wenping Zhang ◽  
Jinzhao Wang
Keyword(s):  
Cylindrical Shell ◽  
Fourier Series ◽  
Boundary Conditions ◽  
Accurate Solution ◽  
Vibration Characteristics ◽  
Series Method ◽  
Mechanical Coupling ◽  
Fourier Series Method ◽  
Characteristics Analysis ◽  
Improved Fourier Series Method

A simple yet accurate solution procedure based on the improved Fourier series method (IFSM) is applied to the vibration characteristics analysis of a cylindrical shell-circular plate (S-P) coupled structure subjected to various boundary conditions. By applying four types of coupling springs with arbitrary stiffness at the junction of the coupled structure, the mechanical coupling effects are completely considered. Each of the plate and shell displacement functions is expressed as the superposition of a two-dimensional Fourier series and several supplementary functions. The unknown series-expansion coefficients are treated as the generalized coordinates and determined using the familiar Rayleigh-Ritz procedure. Using the IFSM, a unified solution for the S-P coupled structure with symmetrical and asymmetrical boundary conditions can be derived directly without the need to change either the equations of motion or the expressions of the displacements. This solution can be verified by comparing the current results with those calculated by the finite-element method (FEM). The effects of several significant factors, including the restraint stiffness, the coupling stiffness, and the situation of coupling, are presented. The forced vibration behaviors of the S-P coupled structure are also illustrated.

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