scholarly journals Interaction of a Ring-Reinforced Shell and a Fluid Medium

1968 ◽  
Vol 35 (1) ◽  
pp. 139-147 ◽  
Author(s):  
Jerry W. Berglund ◽  
Jerome M. Klosner
Keyword(s):  
Circular Cylindrical Shell ◽  
Salt Water ◽  
Power Series Expansion ◽  
Cylindrical Wave ◽  
Acoustic Medium ◽  
Steel Shell ◽  
Fluid Medium ◽  
Transient Dynamic ◽  
Wave Approximation ◽  
Fluid Field

This work is concerned with the transient dynamic response of a periodically ring-reinforced, infinitely long, circular cylindrical shell to a uniform pressure suddenly applied through the surrounding acoustic medium. The incident particle velocity is zero, and the rings are assumed to be slightly flexible. A classical theory of the Donnell type is used to analyze the shell while the fluid is described by the linear acoustic field equation. The solution is obtained by assuming a power series expansion in the ring stiffness parameter and utilizing a technique which reduces the transient dynamic problem to an equivalent steady-state formulation. Numerical results are presented for a steel shell immersed in salt water for different ring spacings. For the case of rigid rings, a cylindrical and plane wave approximation was also used to represent the fluid field. It is shown that the cylindrical wave approximation yields reasonably accurate results. Flexible ring results, although limited, indicate that undamped or nonradiating components of the shell vibration are activated.

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.

The Transient Motion of a Cylindrical Shell of Arbitrary Cross Section in an Acoustic Medium

1977 ◽  
Vol 44 (3) ◽  
pp. 482-486 ◽  
Author(s):  
B. S. Berger ◽  
M. E. Palmer
Keyword(s):  
Cylindrical Shell ◽  
Cross Section ◽  
Arbitrary Cross Section ◽  
Acoustic Medium ◽  
Fluid Equation ◽  
Fluid Medium ◽  
Transient Motion ◽  
Fluid Field ◽  
The Laplace Transform ◽  
Difference Form

A solution has been constructed for the transient motion of a viscoelastic cylindrical shell of the arbitrary cross section, surrounded by a fluid medium. The fluid region external to the shell is mapped into the interior of a rectangle. The transformed fluid equation together with the shell equations are expressed in finite-difference form and the time variable suppressed through the application of the Laplace transform. Shell displacements and acoustic pressures are found over the fluid field and at the fluid solid interface.

Transient Interaction of a Circular Plate and a Fluid Medium

1979 ◽  
Vol 46 (1) ◽  
pp. 26-30 ◽  
Author(s):  
J. W. Berglund
Keyword(s):  
Boundary Conditions ◽  
Circular Plate ◽  
Applied Pressure ◽  
Plate Boundary ◽  
Fluid Medium ◽  
Fluid Field ◽  
Elastic Circular Plate ◽  
Unstrained State ◽  
State Of Rest ◽  
Acoustic Fluid

The transient dynamic response of an elastic circular plate subjected to a suddenly applied pressure is determined for several edge boundary conditions. The plate boundary is attached to a semi-infinite, radially rigid tube which is filled with an acoustic fluid, and pressure is applied to the in-vacuo side of the plate. The transient solution is determined by using a technique in which the plate is subjected to a periodic pressure function constructed of appropriately signed and time-shifted Heaviside step functions, and by relying on a physical mechanism which returns the plate and fluid near the plate to an unstrained state of rest between pulses. The plate response is presented for a number of radius-to-thickness ratios and edge boundary conditions when interacting with water. Comparisons are also made with solutions obtained using a plane wave approximation to the fluid field.

Diffraction by a cylinder with a variable surface impedance

1962 ◽  
Vol 267 (1330) ◽  
pp. 329-350 ◽  
Keyword(s):  
Green Function ◽  
Power Series ◽  
Power Series Expansion ◽  
Variable Coefficients ◽  
Cylindrical Wave ◽  
Variable Surface ◽  
Second Order Difference Equation ◽  
Order Difference Equation ◽  
Image Representations ◽  
Constant Impedance

A solution is obtained for the two-dimensional electromgnetic Green function for a circular cylinder with a peripherally varying surface im pedance. The variations about an arbitrary constant impedance have a small amplitude a and a sinusoidal spatial dependence. A cylindrical wave formulation leads to a specification of the wave amplitudes in terms of an in-homogeneous, second-order difference equation with variable coefficients, which is solved by assuming the expansibility of the solution as a power series in α. The derivation is carried out by a characteristic Green function procedure which yields directly various alternative representations of the solution. Special emphasis is placed on image representations in an infinitely extended angular space, and on their utility for asymptotic evaluation in the quasi-optic wavelength range. These aspects are stressed in a discussion of the constant impedance cylinder result which constitutes the leading term (α 0 power) in the power series expansion.

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.

Numerical Simulation of Fiuid Field of Molten Steel in the Mold on 700mm×700mm Billet Continuous Caster

2010 ◽  
Vol 160-162 ◽  
pp. 151-156
Author(s):  
Ming Hua Bai ◽  
Rui Song Tong ◽  
Jun Li Ge
Keyword(s):  
Process Parameters ◽  
Molten Steel ◽  
Continuous Caster ◽  
Engineering Application ◽  
Submerged Entry Nozzle ◽  
Steel Shell ◽  
Fluid Field ◽  
The Stability ◽  
Continuous Casting Billet

The fluid flow of Q235 molten steel in 700mm×700mm billet mold has been numerically simulated by a software FLUENT. By comparing the influence of submerged entry nozzle with different immersed depths, different number of holes and different opening angles on the distribution of fluid field, the structure of mold and the involved process parameters are optimized. With the application of the optimized structure and process parameters, the stability of fluid field is increased and the thickness uniformity of steel shell is improved, so that the quality of continuous casting billet is ameliorated, which provides a theoretical basis for engineering application.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document