Coupled finite element and boundary element capability for acoustic scattering from general structures

1986 ◽  
Vol 80 (S1) ◽  
pp. S73-S73
Author(s):  
Gordon C. Everstine ◽  
Louise S. Schuetz
Keyword(s):  
Finite Element ◽  
Boundary Element ◽  
Acoustic Scattering

Coupled Finite Element/Boundary Element Method for the Analysis of the Acoustic Scattering From Elastic Structures

1995 ◽  
Author(s):  
Bertrand Dubus ◽  
Antoine Lavie ◽  
Dominique Decultot ◽  
Gérard Maze
Keyword(s):  
Finite Element ◽  
Boundary Element ◽  
Acoustic Waves ◽  
Acoustic Scattering ◽  
Resonant Mode ◽  
Mode Shapes ◽  
Thin Cylindrical Shell ◽  
Isolation And Identification ◽  
Fluid Medium ◽  
Physical Phenomena

Abstract Considerable interest has been expressed recently in the scattering of acoustic waves from elastic targets. For structures of arbitrary shapes, the numerical method relying upon a finite element description of the solid part and a boundary element description of the waves propagating in the infinite fluid medium is the most commonly used. This paper presents a coupling between the ATILA finite element code and the EQI boundary element code performed using a solid variable methodology. Results are presented for a thin cylindrical shell bounded by hemispherical endcaps which are insonified at axial and normal incidences. Comparisons are made with measurements of backscattered pressure spectra and angular patterns obtained with the quasi-harmonic MIIR (Method of Isolation and Identification of Resonances). Emphasis is put on post-processing techniques contributing to the interpretation of physical phenomena such as the extraction of resonant mode shapes.

Acoustic Scattering by Two Submerged Spherical Shells

1998 ◽  
Vol 06 (04) ◽  
pp. 421-434 ◽  
Author(s):  
Gordon C. Everstine ◽  
Guillermo C. Gaunaurd ◽  
Hanson Huang
Keyword(s):  
Exact Solution ◽  
Finite Element ◽  
Boundary Element ◽  
Series Solution ◽  
Spherical Wave ◽  
Acoustic Scattering ◽  
Element Model ◽  
Computer Code ◽  
Structural Acoustics ◽  
Coupling Coefficients

We validate, using a coupled finite element/boundary element computer code, a recently-developed1 series solution for the structural acoustics problem of scattering from two submerged spherical elastic shells. Although the general purpose computational tools for acoustic scattering have never been restricted to single scatterers, the availability of the series solution provides, for the first time, the mutual validation of both exact and numerical approaches for a multiple elastic scatterer problem. The excellent agreement between the two solutions presented thus allows this problem to be added to the short list of existing benchmark structural acoustics problems possessing an analytic solution. For the purposes of this comparison, the direction of incidence is taken as parallel with the axis joining the two shells. The numerical solution uses the NASHUA code, which couples a finite element shell model of the two shells with a boundary element model of the surrounding fluid. The exact solution is found by expanding in terms of classical modal series and uses the addition theorem for the spherical wave functions. The exact solution requires coupling coefficients that are expressed in terms of sums of products of Wigner 3-j symbols (or Clebsch-Gordan coefficients).

Application of the Boundary Element Method and Modal Analysis to Tire Acoustics Problems

1993 ◽  
Vol 21 (2) ◽  
pp. 66-90 ◽  
Author(s):  
Y. Nakajima ◽  
Y. Inoue ◽  
H. Ogawa
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Acoustic Radiation ◽  
Traffic Noise ◽  
Noise Prediction ◽  
Prediction System ◽  
Tire Noise ◽  
Acoustic Contribution ◽  
Element Method

Abstract Road traffic noise needs to be reduced, because traffic volume is increasing every year. The noise generated from a tire is becoming one of the dominant sources in the total traffic noise because the engine noise is constantly being reduced by the vehicle manufacturers. Although the acoustic intensity measurement technology has been enhanced by the recent developments in digital measurement techniques, repetitive measurements are necessary to find effective ways for noise control. Hence, a simulation method to predict generated noise is required to replace the time-consuming experiments. The boundary element method (BEM) is applied to predict the acoustic radiation caused by the vibration of a tire sidewall and a tire noise prediction system is developed. The BEM requires the geometry and the modal characteristics of a tire which are provided by an experiment or the finite element method (FEM). Since the finite element procedure is applied to the prediction of modal characteristics in a tire noise prediction system, the acoustic pressure can be predicted without any measurements. Furthermore, the acoustic contribution analysis obtained from the post-processing of the predicted results is very helpful to know where and how the design change affects the acoustic radiation. The predictability of this system is verified by measurements and the acoustic contribution analysis is applied to tire noise control.

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