scholarly journals A simplified boundary element formulation for acoustic radiation and scattering for axisymmetric bodies and boundary conditions

1985 ◽  
Vol 78 (S1) ◽  
pp. S27-S28
Author(s):  
Benjamin Soenarko ◽  
A. F. Seybert
Keyword(s):  
Boundary Conditions ◽  
Boundary Element ◽  
Acoustic Radiation ◽  
Element Formulation ◽  
Axisymmetric Bodies

scholarly journals Boundary element formulation for elastoplastic analysis of axisymmetric bodies

1982 ◽  
Vol 6 (2) ◽  
pp. 130-135 ◽  
Author(s):  
M Doblaré ◽  
J.C.F Telles ◽  
C.A Brebbia ◽  
E Alarcon
Keyword(s):  
Boundary Element ◽  
Elastoplastic Analysis ◽  
Element Formulation ◽  
Axisymmetric Bodies

Numerical analysis of acoustic radiation properties of laminated composite flat panel in thermal environment: A higher-order finite-boundary element approach

2017 ◽  
Vol 232 (18) ◽  
pp. 3235-3249 ◽  
Author(s):  
Nitin Sharma ◽  
Trupti Ranjan Mahapatra ◽  
Subrata Kumar Panda
Keyword(s):  
Boundary Element ◽  
Thermal Loading ◽  
Thermal Environment ◽  
Acoustic Radiation ◽  
Shear Deformation Theory ◽  
Laminated Composite ◽  
Higher Order ◽  
Element Formulation ◽  
Present Scheme ◽  
Acoustic Responses

In this article, the vibration-induced acoustic responses of laminated composite flat panels subjected to harmonic mechanical excitation under uniform temperature load are investigated numerically. The natural frequencies alongside corresponding modes of the flat panels resting on an infinite rigid baffle are obtained by using finite element method in the framework of the higher-order shear deformation theory. A coupled finite and boundary element formulation is then employed to acquire the acoustic responses. The governing equation for the sound radiaiton from the vibrating structures is derived by solving the Helmholtz wave equation. The vibration and acoustic responses are computed by using the present scheme via an in-house computer code developed in MATLAB environment. In order to avoid any excess thermal loading conditions first, the critical buckling temperature of the panel structure is obtained and authenticated with the benchmark values. Further, the sound power levels for isotropic and laminated composite panels are computed using the present scheme and validated with the existing results in the published literature. Finally, the influence of lamination scheme, support conditions and modular ratio on the acoustic radiation behavior of laminated composite flat panels in an elevated thermal environment is studied through various numerical examples. The thermal load is found to have substantial influence on the stiffness of the panels and the peaks in the free vibration responses tend to shift to lower frequencies for higher temperatures. It is also inferred that the panels radiate less efficiently whereas the overall sound pressure level is found to follow an increasing trend with increasing temperature.

Parallel Boundary Element Solutions of Block Circulant Linear Systems for Acoustic Radiation Problems With Rotationally Symmetric Boundary Surfaces

2012 ◽  
Author(s):  
Kenneth D. Czuprynski ◽  
John B. Fahnline ◽  
Suzanne M. Shontz
Keyword(s):  
Boundary Element ◽  
Parallel Algorithm ◽  
Linear Systems ◽  
Acoustic Radiation ◽  
Circulant Matrices ◽  
Element Formulation ◽  
Element Analysis ◽  
Low Frequencies ◽  
Rotationally Symmetric ◽  
Boundary Surfaces

We propose a distributed parallel algorithm for the solution of block circulant linear systems arising from acoustic radiation problems with rotationally symmetric boundary surfaces. When large structural acoustics problems are solved using a coupling finite element/boundary element formulation, the most time consuming part of the analysis is the solution of the linear system of equations for the boundary element computation. In general, the problem is solved frequency by frequency, and the coefficient matrix for the boundary element analysis is fully populated and exhibits no exploitable structure. This typically limits the number of acoustic degrees of freedom to 10–20 thousand. Because acoustic boundary element calculations require approximately six elements per wavelength to produce accurate solutions, the formation is limited to relatively low frequencies. However, when the outer surface of the structure is rotationally symmetric, the system of linear equations becomes block circulant. Building upon a known inversion formula for block circulant matrices, a parallel algorithm for the efficient solution of linear systems arising from acoustic radiation problems with rotationally symmetric boundary surfaces is developed. We show through a runtime, speedup, and efficiency analysis that the reductions in computation time are significant for an increasing number of processors.

scholarly journals Estimation of Soil Electrical Properties in a Multilayer Earth Model with Boundary Element Formulation

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
T. Islam ◽  
Z. Chik ◽  
M. M. Mustafa ◽  
H. Sanusi
Keyword(s):  
Boundary Conditions ◽  
Boundary Element ◽  
Earth Model ◽  
Element Formulation ◽  
Soil Resistivity ◽  
Resistivity Ratio ◽  
Soil Medium ◽  
Near Surface ◽  
Soil Model ◽  
Geotechnical Investigations

This paper presents an efficient model for estimation of soil electric resistivity with depth and layer thickness in a multilayer earth structure. This model is the improvement of conventional two-layer earth model including Wenner resistivity formulations with boundary conditions. Two-layer soil model shows the limitations in specific soil characterizations of different layers with the interrelationships between soil apparent electrical resistivity (ρ) and several soil physical or chemical properties. In the multilayer soil model, the soil resistivity and electric potential at any points in multilayer anisotropic soil medium are expressed according to the variation of electric field intensity for geotechnical investigations. For most soils with varying layers, multilayer soil resistivity profile is therefore more suitable to get soil type, bulk density of compacted soil and to detect anomalous materials in soil. A boundary element formulation is implemented to show the multilayer soil model with boundary conditions in soil resistivity estimations. Numerical results of soil resistivity ratio and potential differences for different layers are presented to illustrate the application, accuracy, and efficiency of the proposed model. The nobility of the research is obtaining multilayer soil characterizations through soil electric properties in near surface soil profile.

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