scholarly journals Scattering acoustic from one-layered cylindrical shell: Estimation of the radius ratio using reduced cutoff frequencies of circumferential waves

2020 ◽  
Vol 14 (2) ◽  
Author(s):  
Younes Khandouch ◽  
El Houcein Aassif ◽  
Said Agounad ◽  
Gérard Maze
Keyword(s):  
Neural Networks ◽  
Cylindrical Shell ◽  
Acoustic Scattering ◽  
Radius Ratio ◽  
Natural Mode ◽  
Elastic Cylindrical Shell ◽  
Geometrical Properties ◽  
Cutoff Frequencies ◽  
Mode Method ◽  
Circumferential Waves

The obtained results from previous studies done in the acoustic scattering of a plane wave by an elastic cylindrical shell, show that the acoustic resonances of a cylindrical shell are related to its physical and geometrical properties. In order to estimate the radius ratio of an airfield immersed cylindrical shell, using reduced cutoff frequencies of circumferential waves that propagate around it. In this work, an approach based on the artificial neural networks was proposed. This approach uses the reduced cutoff frequencies of circumferential waves, extracted using modal isolation plan representation us the analyzing data, in the object to obtain the value of the radius ratio corresponding to the studied cylindrical shell. The proposed approach allows us to estimate accurately the values of the radius ratio of a copper cylindrical shell, and can help us to resolve other problems related to scattering acoustic. Furthermore, it can be used to estimate various parameters of a cylindrical shell starting from the characteristics of which it is disposed. The proposed approach used in this study does not present any approximation as in the case of the natural mode method which assimilate the cylindrical shell to the plate with the same thickness.

Approximate Formulas for Cylindrical Shell Free Vibration Based on Vlasov’s and Enhanced Vlasov’s Semi-Momentless Theory

2018 ◽  
Author(s):  
Igor Orynyak ◽  
Yaroslav Dubyk
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Circular Cylindrical Shell ◽  
Equations Of Motion ◽  
Middle Surface ◽  
Axial Direction ◽  
Mode Shapes ◽  
Natural Mode ◽  
Transverse Deflection ◽  
Approximate Formulas

Simple approximate formulas for the natural frequencies of circular cylindrical shells are presented for modes in which transverse deflection dominates. Based on the Donnell-Mushtari thin shell theory the equations of motion of the circular cylindrical shell are introduced, using Vlasov assumptions and Fourier series for the circumferential direction, an exact solution in the axial direction is obtained. To improve the results assumptions of Vlasov’s semimomentless theory are enhanced, i.e. we have used only the hypothesis of middle surface inextensibility to obtain a solution in axial direction. Nonlinear characteristic equations and natural mode shapes, are derived for all type of boundary conditions. Good agreement with experimental data and FEM is shown and advantage over the existing formulas for a variety of boundary conditions is presented.

Acoustic wave diffraction by an elastic cylindrical shell with viscous filling

1989 ◽  
Vol 25 (7) ◽  
pp. 662-667 ◽  
Author(s):  
O. B. Kachaenko ◽  
L. S. Pal'ko ◽  
N. A. Shul'ga
Keyword(s):  
Cylindrical Shell ◽  
Acoustic Wave ◽  
Wave Diffraction ◽  
Elastic Cylindrical Shell

scholarly journals An Evaluation of Active Noise Control in a Cylindrical Shell

1989 ◽  
Vol 111 (3) ◽  
pp. 337-342 ◽  
Author(s):  
R. J. Silcox ◽  
H. C. Lester ◽  
S. B. Abler
Keyword(s):  
Cylindrical Shell ◽  
Analytical Model ◽  
Noise Control ◽  
Active Noise Control ◽  
Effective Control ◽  
Elastic Cylindrical Shell ◽  
Noise Sources ◽  
Active Noise ◽  
Fixed Array ◽  
Forced Responses

This paper examines the physical mechanisms governing the use of active noise control in an extended volume of a cylindrical shell. Measured data were compared with computed results from a previously derived analytical model based on infinite shell theory. For both the analytical model and experiment, the radiation of external monopoles is coupled to the internal acoustic field through the radial displacement of the thin, elastic, cylindrical shell. An active noise control system was implemented inside the cylinder using a fixed array of discrete monopole sources, all of which lie in the plane of the exterior noise sources. Good agreement between measurement and prediction was obtained for both internal pressure response and overall noise reduction. Attenuations in the source plane greater than 15 dB were recorded along with a uniformly quieted noise environment over an indicative length inside the experimental model. Results indicate that for forced responses with extended axial distributions, axial arrays of control sources may be required. Finally, the Nyquist criteria for the number of azimuthal control sources is shown to provide for effective control over the full cylinder cross section.

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