Cambridge Collaborative Inc.

Concord, MA, United States

Cambridge Collaborative Inc.

Concord, MA, United States
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Manning J.E.,Cambridge Collaborative Inc. | Musser C.T.,Cambridge Collaborative Inc. | Manning S.J.,Cambridge Collaborative Inc. | Shen M.,Corning Inc. | And 2 more authors.
41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012 | Year: 2012

Interior noise of passenger vehicles due to fluctuating turbulent pressures on the exterior of the vehicle ("wind noise") is a large source of customer complaints. Studies have shown that at higher frequencies, the primary path of these turbulent wind pressures to the passenger interior is through the vehicle window glass. This suggests that modifications to the vehicle window glass represent potential for wind noise improvements. Data also suggests that at lower frequencies other paths such as the floor dominate the wind noise contribution. This implies that vehicle window glass can be designed for better high-frequency acoustic performance as well as reduced weight without degrading the low-frequency interior noise. This finding is significant since reducing vehicle weight is an increasingly important design goal. This paper presents the results of new test data showing individual relative contributions of the dominant vehicle window glass paths to interior noise for an operating condition where wind noise is dominant. The test setup and objectives are given. The results and path contribution ranking versus frequency are shown. The implications for further analytical studies and the most effective changes to improve acoustic performance are discussed, keeping weight reduction goals in mind.


Shen M.,Corning Inc. | Musser C.T.,Cambridge Collaborative Inc. | Manning J.E.,Cambridge Collaborative Inc.
41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012 | Year: 2012

The interior noise of passenger vehicles is often dominated at higher frequencies by transmission through the glasses. One of the main reasons this occurs is that a conventional sound package cannot be applied to the glasses. The sound package is used on other vehicle subassemblies such as the dash, floor, and doors. Also, turbulent flows have prominent reattachment regions downstream from the cowl, side mirrors, and pillars that create locally high source levels that are directly transmitted as noise into the vehicle interior through the glasses. Use of multilayer laminated glasses has been shown to provide a great benefit in reducing passenger vehicle noise. When paths other than the glasses are dominant, as is the case at lower frequencies, the total weight of the glasses can also be reduced while avoiding significant interior noise increases. This paper presents the results from analytical studies of the potential for the application of lower surface density glass laminate versus the resulting interior noise performance for different glass laminate designs. The analytical modeling approach is based on Statistical Energy Analysis (SEA) and the correlation test data are described. Copyright © (2012) by the Institute of Noise Control Engineering (INCE).


Herrin D.W.,University of Kentucky | Liu J.,University of Kentucky | Martinus F.,Trane Inc. | Kato D.J.,Cambridge Collaborative Inc. | Cheah S.,Cummins Power Generation
Noise Control Engineering Journal | Year: 2010

The inverse boundary element method (BEM) is a numerical procedure whereby sound pressure measurements in the near field are used to predict the vibration on a vibrating surface. After the vibration on the surface (or particle velocity in the case of an opening) is determined, the sound pressure in the far field can be predicted using a forward BEM analysis. This paper will examine the applicability of the inverse BEM to predicting sound pressure in the far field on two examples; an engine cover and generator set.The results indicate that the inverse BEM can be used to accurately predict far field sound pressure. Additionally, it is demonstrated that a partial or patch BEM model of a surface can be utilized successfully in some instances as a means of reducing the computation time. © 2009 Institute of Noise Control Engineering.


Manning P.,Cambridge Collaborative Inc | Manning J.,Cambridge Collaborative Inc | Musser C.,Cambridge Collaborative Inc | Peng G.,Jaguar Land Rover
SAE International Journal of Materials and Manufacturing | Year: 2013

The contribution of wind noise through the glasses into the vehicle cabin is a large source of customer concern. The wind noise sources generated by turbulent flow incident on the vehicle surfaces and the transmission mechanisms by which the noise is transmitted to the interior of the vehicle are complex and difficult to predict using conventional analysis techniques including Computational Fluid Dynamics (CFD) and acoustic analyses are complicated by the large differences between turbulent pressures and acoustic pressures. Testing in dedicated acoustic wind tunnel (AWT) facilities is often performed to evaluate the contribution of wind noise to the vehicle interior noise in the absence of any other noise sources. However, this testing is time-consuming and expensive and test hardware for the vehicle being developed is often not yet available at early stages of vehicle design. In addition, modifications of the vehicle exterior geometry that may be beneficial to interior noise are often difficult to implement during the testing or to evaluate properly via test. This paper describes a test-based approach to measuring and understanding the contribution of exterior wind noise to the interior cabin noise through the individual glasses and the development of a correlated Statistical Energy Analysis (SEA) model capable of predicting the effect of a design change to any combination of thickness or material changes to the glasses. AWT testing was performed with interior microphones, accelerometers on the glasses, and arrays of flat exterior pressure transducers to establish the acoustic and structural-acoustic transfer functions to the interior. An underbody skirt, extensive taping of exterior gaps, and “blocker” parts on the interior of the glasses were used in order to isolate the noise contribution through individual glasses. Two versions of the front side glass -monolithic and laminated - were tested to compare the effect of the glass material and damping on transmitted wind noise and to provide a reference from which the wind noise load at this important location could be inferred. The data set from this testing was processed and used to correlate an SEA model of the test vehicle capable of being used for design studies of the effect of the glasses on the interior wind noise. © 2013 SAE International.


Musser C.T.,Cambridge Collaborative Inc. | Da Silva M.M.,Ford Motor Company | Kempt R.,Ford Motor Company
41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012 | Year: 2012

SEA (Statistical Energy Analysis) for automotive NVH development has been employed for more than 20 years. SEA is uniquely suited to providing predictions of main noise contribution paths and overall interior noise due to individual or combined airborne or structureborne noise sources at higher frequencies. Existing SEA vehicle models may be easily adapted for acoustic design studies for new vehicle programs, allowing fast design study predictions at the first stages of vehicle design before test hardware or mature FEA models are available. For greater confidence in the model and results a model validation from laboratory test data is recommended. This paper discusses an SEA model validation process using hemi-anechoic laboratory test data with artificial acoustic sources and a windowing methodology employing blocker parts on the flanking paths to study and validate the contribution of the dominant individual noise transfer paths. Testing strategy, methodology, main results, and lessons learned are presented. Key SEA modeling input parameters and validation approach are discussed. Comparison of test data to correlated model and representative NVH design sensitivity results are shown. Conclusions about the testing, model correlation, and use of the correlated model to support future vehicle program design are given.


Musser C.T.,Cambridge Collaborative Inc. | Manning J.E.,Cambridge Collaborative Inc. | Peng G.C.,Jaguar Land Rover
41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012 | Year: 2012

Predicting the wind noise contribution to interior vehicle noise from the interaction of the exterior turbulent flows with the greenhouse panels is an ongoing challenge for the automobile industry. Effective NVH design requires an understanding of the relative wind noise contribution paths and mechanisms. This paper presents a test-based approach to characterizing the dominant wind noise contribution paths and transmission mechanisms for a representative sport utility vehicle tested in an acoustic wind tunnel. Use of heavy blocker parts on important flanking paths allows contribution from individual greenhouse panels to be measured via a windowing method. Use of interior microphones together with greenhouse panel accelerometers and some minimal SEA (Statistical Energy Analysis) modeling allows separation of noise contribution into acoustic and structural mechanisms, thereby providing insight into the most effective acoustic design changes. The relative ranking of the main noise transfer paths are presented along with their estimated contribution from radiated noise. A recommended methodology for using these results as an empirically based method of wind noise improvement and for performing more detailed design studies with SEA modeling is presented.


Musser C.,Cambridge Collaborative Inc. | Manning J.,Cambridge Collaborative Inc. | Peng G.C.,Jaguar Land Rover
SAE Technical Papers | Year: 2011

Statistical Energy Analysis (SEA) is the standard analytical tool for predicting vehicle acoustic and vibration responses at high frequencies. SEA is commonly used to obtain the interior Sound Pressure Level (SPL) due to each individual noise or vibration source and to determine the contribution to the interior noise through each dominant transfer path. This supports cascading vehicle noise and vibration targets and early evaluation of the vehicle design to effectively meet NVH targets with optimized cost and weight. A common misconception is that SEA is only capable of predicting a general average interior SPL for the entire vehicle cabin and that the differences between different locations such as driver's ear, rear passenger's ear, lower interior points, etc., in the vehicle cannot be analytically determined by an SEA model. However, because the interior acoustic energy distribution varies due to absorption and distance effects that can be modeled, an SEA model is capable of predicting the SPL at different interior locations with good accuracy at high frequencies. This paper discusses the SEA modeling assumptions used to generate a typical model of a vehicle cabin interior and surrounding structure. The distribution of acoustic absorption and its effect on the local interior SPL responses are addressed. Measurements of transfer functions to various points of the vehicle interior from exterior and interior acoustic sources and structureborne sources for a typical vehicle are presented and compared to SEA model predictions. Observations and recommendations about typical interior transfer function correlation, modeling limitations, and use of the SEA model as a design tool are given. Copyright © 2011 SAE International.


Manning P.,Cambridge Collaborative Inc. | Manning J.,Cambridge Collaborative Inc. | Musser C.,Cambridge Collaborative Inc. | Peng G.,Jaguar Land Rover
SAE Technical Papers | Year: 2013

The contribution of wind noise through the glasses into the vehicle cabin is a large source of customer concern. The wind noise sources generated by turbulent flow incident on the vehicle surfaces and the transmission mechanisms by which the noise is transmitted to the interior of the vehicle are complex and difficult to predict using conventional analysis techniques including Computational Fluid Dynamics (CFD) and acoustic analyses are complicated by the large differences between turbulent pressures and acoustic pressures. Testing in dedicated acoustic wind tunnel (AWT) facilities is often performed to evaluate the contribution of wind noise to the vehicle interior noise in the absence of any other noise sources. However, this testing is time-consuming and expensive and test hardware for the vehicle being developed is often not yet available at early stages of vehicle design. In addition, modifications of the vehicle exterior geometry that may be beneficial to interior noise are often difficult to implement during the testing or to evaluate properly via test. This paper describes a test-based approach to measuring and understanding the contribution of exterior wind noise to the interior cabin noise through the individual glasses and the development of a correlated Statistical Energy Analysis (SEA) model capable of predicting the effect of a design change to any combination of thickness or material changes to the glasses. AWT testing was performed with interior microphones, accelerometers on the glasses, and arrays of flat exterior pressure transducers to establish the acoustic and structural-acoustic transfer functions to the interior. An underbody skirt, extensive taping of exterior gaps, and blocker parts on the interior of the glasses were used in order to isolate the noise contribution through individual glasses. Two versions of the front side glass -monolithic and laminated - were tested to compare the effect of the glass material and damping on transmitted wind noise and to provide a reference from which the wind noise load at this important location could be inferred. The data set from this testing was processed and used to correlate an SEA model of the test vehicle capable of being used for design studies of the effect of the glasses on the interior wind noise. Copyright © 2013 SAE International.


Musser C.,Cambridge Collaborative Inc. | Marques Da Silva M.,MSX International Do Brazil | Lima Alves P.S.,Ford Motor Company
SAE Technical Papers | Year: 2013

For purposes of reducing development time, cost and risk, the majority of new vehicles are derived strongly or at least generally from a surrogate vehicle, often of the same general size or body style. Previous test data and lessons learned can be applied as a starting point for design of the new vehicle, especially at early phases of the design before definite design decisions have been finalized and before prototype of production test hardware is available. This is true as well of vehicle NVH development where most new vehicles being developed are variants of existing vehicles for which the main noise transfer paths from sources of interest are already understood via test results and existing targets. The NVH targets for new vehicles are defined via benchmarking, market considerations, and other higher-level decisions. The objective is then to bridge the gap between test data from surrogate vehicles to direct support of the NVH development of new vehicle programs. Because of its strength in providing analysis predictions of the effect of design changes on vehicle NVH at higher frequencies, Statistical Energy Analysis (SEA) is an established tool for using available test data to correlate an SEA model that can be adapted for early design phase NVH development of new vehicles. The effect of changes to materials, gage thickness, sound package, source levels, or geometry changes on the interior noise levels can be predicted by SEA with good accuracy to support design decisions that must be made early in the program. This paper illustrates with a concrete example an idealized implementation of this process. The main test plan design considerations for a baseline surrogate vehicle are discussed. Some key test results and their uses are presented. The updating and correlation of an SEA model representing the baseline vehicle are shown. The objective methods for determining the effectiveness of the correlation are given using this vehicle as an example. Finally, the use of a correlated SEA model to effectively support the NVH development of several variant vehicle programs at an early phase of the design process is presented along with suggestions for the best use of this design tool, its advantages and limitations, and the most effective roles it can serve to support the overall vehicle design cycle. Copyright © 2013 SAE International.

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