Case study: Correlation between boundary and finite element determination of large silencer transmission loss

2021 ◽  
Vol 69 (4) ◽  
pp. 276-287
Author(s):  
Kangping Ruan ◽  
T.W. Wu ◽  
D.W. Herrin
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Cross Sections ◽  
Transmission Loss ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Cross Sectional ◽  
Element Determination ◽  
Element Method

Silencers used in the power generation industry generally have large ducts entering and leaving the silencer. With large cross-sectional dimensions, the plane wave cutoff frequency will be exceeded at a low frequency so that transmission loss can no longer be evaluated by assuming constant sound pressure over a cross-section. More sophisticated calculation and processing approaches are necessary. In this research, the boundary element method is used in conjunction with a reciprocal identity method to determine the transmission loss for rectangular and circular cross-sections: the two configurations that cover most real-world designs. The boundary element method is compared to a finite element method strategy where the transmission loss is determined using an automatically matched layer boundary condition at the inlet and outlet. This approach can be used in most commercial software. Although these two approaches have little in common, transmission loss results compare well with one other. Validation by comparison is helpful because analytical solutions are only available for simple axisymmetric cases. Methods are compared for practical configurations like parallel-baffle silencers and reactive silencers.

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.

Postbuckling Analysis of Plates Under Combined Loads by a Mixed Finite Element and Boundary Element Method

1993 ◽  
Vol 115 (3) ◽  
pp. 262-267 ◽  
Author(s):  
J. Q. Ye
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Mixed Boundary ◽  
Mixed Finite Element ◽  
Plane Deformation ◽  
Thin Plates ◽  
Combined Loads ◽  
Element Method

The postbuckling behavior of thin plates under combined loads is studied in this paper by using a mixed boundary element and finite element method. The transverse and the in-plane deformation of the plates are analyzed by the boundary element method and the finite element method, respectively. Spline functions were used as the interpolation functions and shape functions in the solution of both methods. A quadratic rectangular spline element is adopted in the finite element procedure. Numerical results are given for typical problems to show the effectiveness of the proposed approach. The possibilities to extend the method developed in this paper to more complicated postbuckling problems are discussed in the concluding section.

Combined finite element-boundary element method modelling of elastic multi-asperity contacts

2009 ◽  
Vol 223 (5) ◽  
pp. 767-776 ◽  
Author(s):  
S Ilincic ◽  
G Vorlaufer ◽  
P A Fotiu ◽  
A Vernes ◽  
F Franek
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Hertzian Contact ◽  
Multilayer Systems ◽  
Influence Coefficients ◽  
Asperity Contacts ◽  
First Time ◽  
Element Algorithm ◽  
Element Method

A novel formulation of elastic multi-asperity contacts based on the boundary element method (BEM) is presented for the first time, in which the influence coefficients are numerically calculated using a finite element method (FEM). The main advantage of computing the influence coefficients in this manner is that it makes it also possible to consider an arbitrary load direction and multilayer systems of different mechanical properties in each layer. Furthermore, any form of anisotropy can be modelled too, where Green's functions either become very complicated or are not available at all. The rest of the contact analysis is then performed applying a custom-developed boundary element algorithm. The scheme was tested by considering the frictionless contact between a flat surface and a sphere. The obtained results are in good agreement with the analytical solution known for a Hertzian contact. Applied to either a frictionless or a frictional contact between real surfaces of different samples, our FEM-BEM method has shown that the composite roughness of surfaces in contact uniquely determines the contact pressure distribution.

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