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Recent Progress using SEA and CFD to Predict Interior Wind Noise

Vibro-Acoustic Sciences Inc.-Paul G. Bremner
ESI Software S.A., ESI Group-Ming Zhu
Published 2003-05-05 by SAE International in United States
This paper reviews the aero-vibro-acoustic theory required to predict interior wind noise in an automobile passenger cabin. It describes how the exterior flow field needs to be defined as an input source to a statistical energy analysis (SEA) model of the body structural acoustics, with particular emphasis on separation of different wavenumber components. The paper then presents and evaluates the most recent work with unsteady computational fluid dynamics (CFD), as means to provide the required inputs to the SEA model. Comparison of predictions with test data is provided to illustrate progress to date and continuing development directions.
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Building 3D SEA Models from Templates - New Developments

Vibro-Acoustic Sciences Inc.-Denis Blanchet, Andrew Cunningham
Published 2003-05-05 by SAE International in United States
Automobile sound package design requires that a Statistical Energy Analysis (SEA) model be built during initial stages of any vehicle program. This allows design changes, noise path analysis and optimization of the sound package to be performed before any program design freeze. The 3D model building process becomes a critical element since it involves many weeks of work before the model is ready for sound package definition and analysis. This paper introduces new developments in building 3D SEA models using templates. A new set of tools has been developed to further automate the SEA model building process. These tools should enable the user to develop a full vehicle SEA model within a few days. The productivity improvement gained by reducing model building time will allow for a more effective use of SEA models in the vehicle development cycle.
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A Model Study of How Tire Construction and Materials Affect Vibration-Radiated Noise

Vibro-Acoustic Sciences Inc.-Paul Bremner
Purdue Univ.-John Huff, J. Stuart Bolton
Published 1997-05-20 by SAE International in United States
A simple mathematical model was developed and experimentally validated to evaluate how the materials and construction of an automobile tire affect its vibration-radiated noise performance. The mathematical model uses Statistical Energy Analysis (SEA) with modal joint acceptance formulations for wavespeed and radiation efficiency of orthotropically-stiffened and pressurized cylindrical shells. Experimental validation of the model included wavenumber decomposition to determine the dispersion characteristics of an inflated, non-rolling tire in the laboratory. The model is used to conduct a preliminary study into how the various tire constituent materials and construction parameters influence the vibration-radiated noise performance.
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Overview of the Experimental Approach to Statistical Energy Analysis

Vibro-Acoustic Sciences Inc.-Benjamin Cimerman
Ford Motor Co.-Tej Bharj
Published 1997-05-20 by SAE International in United States
Statistical Energy Analysis (SEA) is used to predict wide-bandwidth noise and vibration. That prediction may rely on parameters derived from theory or from test, which essentially means that there are two distinct approaches, analytical SEA and test-based SEA.The latter is the focus of this paper. Both theory and practice are reviewed, so that the current status of the method can be established. This review also provides some insight on what information can be extracted from the experiment, how the measurements must be conducted and how the results must be interpreted.Another important aspect of test-based SEA is its interaction with the more widely used analytical SEA method. It is demonstrated that both methods are complementary and that the analytical and test-based parameters can either be compared or mixed in a “hybrid” SEA,model. Benefits of the combined use of the methods are discussed.The discussions are supported by results obtained for automotive applications. This overview paper will provide the reader with an understanding of the method and its applications.
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Road Noise Modelling Using Statistical Energy Analysis Method

Vibro-Acoustic Sciences Inc.-Paul Bremner, Peter Kasper
Chrysler Corp.-Bangyi Dong, Martin Green, Mark Voutyras
Published 1995-05-01 by SAE International in United States
A mathematical model was developed to evaluate design options for control of road noise transmission into the interior of a passenger car. Both air-borne and structure-borne road noise over the frequency range of 200-5000 Hz was able to be considered using the Statistical Energy Analysis (SEA) method. Acoustic and vibration measurements conducted on a laboratory rolling road were used to represent the tire noise “source” functions. The SEA model was correlated to in car sound pressure level measurements to within 2-4 db accuracy, and showed that airborne noise dominated structure-borne noise sources above 400 Hz. The effectiveness of different noise control treatments was simulated and in some cases evaluated with tests.
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A Comparison of Test-Based and Analytic SEA Models for Vibro-Acoustics of a Light Truck

Vibro-Acoustic Sciences Inc.-Melissa O'Keefe, Paul Bremner
Ford Motor Co.-Heng-yee Chen
Published 1995-05-01 by SAE International in United States
A number of researchers [3],[4] have shown that Statistical Energy Analysis[1] provides a useful framework for test-based noise path analysis - as well purely analytical models. This paper describes the results of a comparative study of two such models - an analytic SEA model and a test-based SEA parameter model - for predicting the Noise Reduction performance of a light truck body.First, the different power balance matrix solutions and SEA subsystem definitions are reviewed. Second the results of the two independent models are compared. For some specific cases of structure-borne noise, the test-based method is shown to be more accurate than the analytic model. Third, means by which individual measured SEA parameters can be integrated into an analytic SEA model are proposed and evaluated. Results indicate that the scope for analytical model improvement, but also highlight the need for more rigorous “consistency” in the way test-based SEA parameters are measured.
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Incorporating Layered Acoustic Trim Materials in Body Structural-Acoustic Models

Vibro-Acoustic Sciences Inc.-Benjamin Cimerman, Paul Bremner
Globe Industries Inc.-Yang Qian, Jeff A. Van Buskirk
Published 1995-05-01 by SAE International in United States
A fully analytical method for the evaluation of noise reduction in a vehicle interior furnished with layered acoustic trim is presented. The method combines calculation of trim Transmission Loss (TL) and Absorption Coefficient with a Statistical Energy Analysis (SEA) calculation of trimmed panel Noise Reduction (NR). This allows for the evaluation of the trim package performance in real operating conditions and ranking of the different air-borne and structure-borne transmission paths.
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