Acoustic Transmission Through Cylindrical Shells Treated with FLD Mechanisms

2009 ◽  
Vol 25 (3) ◽  
pp. 299-306 ◽  
Author(s):  
K. Daneshjou ◽  
R. Talebitooti ◽  
A. Nouri
Keyword(s):  
Cylindrical Shell ◽  
Wave Equations ◽  
Analytical Study ◽  
Circular Cylindrical Shell ◽  
Impedance Method ◽  
Fluid Medium ◽  
Damping Material ◽  
Especial Case ◽  
In Series ◽  
Stiffness Loss

AbstractAnalytical study is conducted in this paper to understand the characteristics of sound transmission through cylindrical shell with free layer damping (FLD) treatment. It is assumed an infinitely long circular cylindrical shell subjected to a plane wave with uniform airflow in the external fluid medium. The damping layer applied on the surface of the shell is represented by HN model with frequency-dependent specifications. An exact solution is obtained by solving the Markus equations of FLD shells and acoustic wave equations simultaneously. As the pressure and displacement terms are expressed in series form, an iterative procedure is founded to cut them with an appropriatenumber of modes. Transmission losses obtained from the solution are compared with “modal-impedance method” for an especial case of untreated shell. Eventually, the numerical results show the effects of stiffness, loss factor and thickness of damping material, and also incident wave angles on TL curves.

Nonlinear Response of an Elastic Cylindrical Shell to a Transient Acoustic Wave

1981 ◽  
Vol 48 (1) ◽  
pp. 15-24 ◽  
Author(s):  
T. L. Geers ◽  
C.-L. Yen
Keyword(s):  
Cylindrical Shell ◽  
Acoustic Wave ◽  
Nonlinear Response ◽  
Circular Cylindrical Shell ◽  
Elastic Cylindrical Shell ◽  
Fluid Medium ◽  
Energy Functionals ◽  
Potential Formulation ◽  
Rigorous Treatment ◽  
Residual Potential

Governing equations are developed for the nonlinear response of an infinite, elastic, circular cylindrical shell submerged in an infinite fluid medium and excited by a transverse, transient acoustic wave. These equations derive from circumferential Fourier-series decomposition of the field quantities appearing in appropriate energy functionals, and from application of the “residual potential formulation” for rigorous treatment of the fluid-structure interaction. Extensive numerical results are presented that provide understanding of the phenomenology involved.

Excitation of an Elastic Cylindrical Shell by a Transient Acoustic Wave

1969 ◽  
Vol 36 (3) ◽  
pp. 459-469 ◽  
Author(s):  
T. L. Geers
Keyword(s):  
Cylindrical Shell ◽  
Acoustic Wave ◽  
Circular Cylindrical Shell ◽  
Elastic Cylindrical Shell ◽  
Sandwich Shell ◽  
Governing Equations ◽  
Fluid Medium ◽  
Method Of Solution ◽  
Plane Step ◽  
Strain Responses

An infinite, elastic, circular cylindrical shell submerged in an infinite fluid medium is engulfed by a transverse, transient acoustic wave. The governing equations for modal shell response are reduced through the application of a new method of solution to two simultaneous equations in time; these equations are particularly amenable to solution by machine computation. Numerical results are presented for the first six modes of a uniform sandwich shell submerged in water and excited by a plane step-wave. These results are then used to evaluate the accuracy of a number of approximations which have been employed previously to treat this and similar problems. The results are also used to compute displacement, velocity, and flexural strain responses at certain points in the sandwich shell.

Transient Response of a Periodically Supported Cylindrical Shell Immersed in a Fluid Medium

1965 ◽  
Vol 32 (3) ◽  
pp. 562-568 ◽  
Author(s):  
Harry Herman ◽  
J. M. Klosner
Keyword(s):  
Cylindrical Shell ◽  
Integral Transform ◽  
Circular Cylindrical Shell ◽  
Fourier Integral ◽  
Cylindrical Wave ◽  
Acoustic Medium ◽  
Steel Shell ◽  
Fluid Medium ◽  
Wave Approximation ◽  
Fourier Integral Transform

The dynamic response of a periodically simply supported, infinitely long, circular cylindrical shell to a pressure suddenly applied through the surrounding acoustic medium is investigated. The incident particle velocity is zero, and the pressure is assumed to have a harmonic spatial variation parallel to the shell axis. The exact solution is obtained by use of a Fourier integral transform, and the resulting inversion integral is evaluated by numerical and asymptotic integration. Two solutions to the same problem are obtained by using a plane and cylindrical wave approximation for the radiated field. The range of their applicability is investigated. For a steel shell in water ccs2=0.08815 it is found that, when the supports are placed three shell diameters apart, the use of the cylindrical wave approximation results in a 5-percent underestimation of the maximum deflection, while when the supports are placed one sixth of a shell diameter apart, the approximations are invalid.

Response of a Ring-Reinforced Cylindrical Shell, Immersed in a Fluid Medium, to an Axisymmetric Step Pulse

1972 ◽  
Vol 39 (2) ◽  
pp. 521-526 ◽  
Author(s):  
J. Crouzet-Pascal ◽  
H. Garnet
Keyword(s):  
Cylindrical Shell ◽  
Applied Load ◽  
Static Load ◽  
Circular Cylindrical Shell ◽  
Complex Interaction ◽  
Dynamic Stresses ◽  
Fluid Medium ◽  
Dynamic Displacement ◽  
Steady State Solutions ◽  
Equal Amplitude

The dynamic response of a ring-stiffened circular cylindrical shell, immersed in a fluid and subjected to a suddenly applied radial load, is investigated. The shell is infinitely long, the stiffening rings are periodically spaced and identical, and the applied load is uniformly distributed. In the analysis, the authors employ a technique involving the superposition of steady-state solutions which they have found, in previous applications, to be more suitable for problems involving complex interaction conditions than the customary transform approaches. The shell response is computed for an applied step pulse. Displacements and stress histories, and variations in their peak levels, are presented for values of ring flexibility, mass, and spacing, varying over a broad range. The response to the dynamic load is also compared to the response obtained for a static load of equal amplitude. It is found, for example, that for a given ring spacing and flexibility, increase in ring mass above a certain level can lead to dynamic stresses and displacements that exceed their static counterparts by large amounts. Such a situation also makes the existence of an oscillating response more likely. When the ring mass has a negligible influence of the shell response, the trends followed by the peak dynamic displacement and stress with ring flexibility are not appreciably different from those followed by the corresponding static quantities. A similar observation can be made concerning the variation of the peak dynamic displacement with ring spacing.

Inelastic Response of an Infinite Cylindrical Shell to Transient Acoustic Waves

1989 ◽  
Vol 56 (4) ◽  
pp. 900-909 ◽  
Author(s):  
Thomas L. Geers ◽  
Chi-Lin Yen
Keyword(s):  
Cylindrical Shell ◽  
Acoustic Waves ◽  
Nonlinear Response ◽  
Circular Cylindrical Shell ◽  
Pressure Profile ◽  
Response Analysis ◽  
Fluid Medium ◽  
Convolution Integrals ◽  
Infinite Cylindrical Shell ◽  
Incident Waves

The geometrically and constitutively nonlinear response of an infinite, circular, cylindrical shell submerged in an infinite fluid medium to a transverse, transient acoustic wave is analyzed. Circumferential Fourier series solutions are obtained through the numerical integration of coupled ordinary differential equations and convolution integrals. Numerical results are presented in the form of response histories, response snapshots, and iso-damage curves for incident waves of rectangular pressure profile. Response solutions obtained with the first-order doubly asymptotic approximation are compared with their “exact” counterparts. It is found that doubly asymptotic approximations are unsuitable for two-dimensional, shock-response analysis of yielding submerged structures.

Plane-Strain Dynamic Response of a Cylindrical Shell—A Comparison Study of Three Different Shell Theories

1968 ◽  
Vol 35 (2) ◽  
pp. 297-305 ◽  
Author(s):  
H. Reismann ◽  
P. S. Pawlik
Keyword(s):  
Cylindrical Shell ◽  
Dynamic Response ◽  
Plane Strain ◽  
Analytical Study ◽  
Circular Cylindrical Shell ◽  
Response Prediction ◽  
Comparison Study ◽  
Membrane Theory ◽  
Rotatory Inertia ◽  
Initial Motion

An analytical study of the plane-strain dynamic response of a circular, cylindrical shell is presented. The shell is subjected to a radially directed concentrated impulse acting on its surface. Solutions are presented within the framework of (a) membrane theory, (b) Flu¨gge theory, and (c) improved theory (including shear deformation and rotatory inertia). A quantitative study of the initial motion of the shell indicates major differences in response prediction of the three theories. An explanation of these differences is offered.

scholarly journals Free Vibration of a Fluid-Filled Circular Cylindrical Shell with Lumped Masses Attached, Using the Receptance Method

1996 ◽  
Vol 3 (3) ◽  
pp. 159-167 ◽  
Author(s):  
Marco Amabili
Keyword(s):  
Cylindrical Shell ◽  
Analytical Study ◽  
Circular Cylindrical Shell ◽  
Free Vibrations ◽  
Frequency Equation ◽  
Structure Interaction ◽  
Steel Tank ◽  
Receptance Method ◽  
Lumped Masses ◽  
Theory Of Shells

The receptance method is applied to the analytical study of the free vibrations of a simply supported circular cylindrical shell that is either empty or filled with an in viscid, incompressible fluid and with lumped masses attached at arbitrary positions. The receptance of the fluid-filled shell is obtained using the added virtual mass approach to model the fluid–structure interaction. The starting data for the computations is the modal properties of the cylinder that can be obtained using any theory of shells. Numerical results are obtained as roots of the frequency equation and also by considering the trivial solution. They are compared to data obtained by experimental modal analysis performed on a stainless steel tank, empty, or filled with water, with a lead mass attached.

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