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Viewing 1 to 30 of 57126
2011-05-17
Journal Article
2011-01-1651
Hideo Suzuki, Takashi Nakashima, Hirokazu Tatekawa, Hisanobu Mizukawa, Michael H. Smith
It is very important to accurately measure rotation frequencies and fluctuations of rotating systems since they cause vibrations and noises, and since they sometimes indicate system malfunctions. Most rotating systems are equipped with electro- or magneto-conductive gears as their components, and rotation pulses are very commonly obtained by installing electromagnetic or electrostatic type sensors closely to target gears, and time dependent (instantaneous) rotation frequencies are obtained from intervals between adjacent pulses. However, since the number of pulses per revolution is relatively small, a method of obtaining instantaneous frequencies from adjacent pulse intervals is not adequate. For these kinds of pulses, instantaneous rotation frequencies are typically derived using the analytic signal (or Hilbert transform) method. In either case, there is an inherent limitation in using rotation pulses obtained from gears.
2011-05-17
Journal Article
2011-01-1649
Andrew J. Morello, Jason R. Blough, Jeffrey Naber, Libin Jia
Research into the estimation of diesel engine combustion metrics via non-intrusive means, typically referred to as “remote combustion sensing” has become an increasingly active area of combustion research. Success in accurately estimating combustion metrics with low-cost non-intrusive transducers has been proven and documented by multiple sources on small scale diesel engines (2-4 cylinders, maximum outputs of 67 Kw, 210 N-m). This paper investigates the application of remote combustion sensing technology to a larger displacement inline 6-cylinder diesel with substantially higher power output (280 kW, 1645 N-m) than previously explored. An in-depth frequency analysis has been performed with the goal of optimizing the estimated combustion signature which has been computed based upon the direct relationship between the combustion event measured via a pressure transducer, and block vibration measured via accelerometers.
2011-05-17
Technical Paper
2011-01-1647
Kristopher Lynch, John Maxon
Gulfstream Aerospace Corporation (GAC) owns and operates an Acoustic Test Facility (ATF) in Savannah, GA. The ATF consists of a Reverberation Chamber, Hemi-Anechoic Chamber, and a Control Room. Types of testing conducted in the ATF include Transmission Loss, Sound Power, and Vibration testing. In addition to accommodating typical types of acoustic testing, the ATF has some unique capabilities. The ATF can be used to conduct testing at cold temperatures representative of up to 45,000 ft flight altitude, while simultaneously taking Transmission Loss measurements of the chilled test sample. Additionally, the ATF has the capability of conducting Transmission Loss testing of a full mockup of the aircraft sidewall, including a section of fuselage, all the thermal/acoustic materials up to and including the interior decorative panel. A sound source capable of very high amplitudes at high frequencies is required to obtain good measurements from testing multiple wall systems such as this.
2011-05-17
Technical Paper
2011-01-1660
Ienkaran Arasaratnam, Saeid Habibi, Christopher Kelly, Tony J. Fountaine, Jimi Tjong
Advanced engine test methods incorporate several different sensing and signal processing techniques for identifying and locating manufacturing or assembly defects of an engine. A successful engine test method therefore, requires advanced signal processing techniques. This paper introduces a novel signal processing technique to successfully detect a faulty internal combustion engine in a quantitative manner. Accelerometers are mounted on the cylinder head and lug surfaces while vibration signals are recorded during engine operation. Using the engine's cam angular position, the vibration signals are transformed from the time domain to the crank-angle domain. At the heart of the transformation lies interpolation. In this paper, linear, cubic spline and sinc interpolation methods are demonstrated for reconstructing vibration signals in the crank-angle domain.
2011-05-17
Technical Paper
2011-01-1656
Albers Albert, Alexander Schwarz
The NVH (Noise Vibration Harshness) behavior of modern vehicles becomes more and more important - especially in terms of new powertrain concepts, like in hybrid electric or full electric vehicles. There are many tools and methods to develop and optimize the NVH behavior of modern vehicles. At the end of the development process, subjective ratings from road tests are very important. For objective analyses, different approaches based on artificial neural networks exist. One example is the AVL-DRIVE™ system, a driveability analysis and benchmarking system which allows, based on a very small set of sensors, an adequate objective rating of the vehicle's driveability. The system automatically detects driving maneuvers and rates the driveability. This article presents a method which is able not only to rate different maneuvers and the behavior of the vehicle but also to detect phenomena and causes in the domain of NVH.
2011-05-17
Technical Paper
2011-01-1612
Dan Faylor
As North American truck manufactures have entered the global market it has become apparent that there are widely varying drive-by noise regulations required in various areas of the world. This paper will describe differences between various test procedures, track layouts, and required levels. Data will be presented showing vehicle results from various procedures, used to quantify differences in noise levels between a range of procedures. Countries were ranked from least restrictive to most restrictive based on test procedures and legal market requirements.
2011-05-17
Technical Paper
2011-01-1611
Dhanesh Purekar
An existing pass by noise data acquisition system was upgraded to provide the sophisticated data analysis techniques and test site efficiency required to comply with the current and future drive by noise regulations. Use of six sigma tool such as voice of the customer helped in defining the customer requirements which were then translated into the desired engineering characteristics using QFD. Pugh concept matrix narrowed down the best option suitable for the test site modifications taking into account the critical constraints such as test complexity, system cost & transparency to the existing drive by noise setup. Features of the new system include data telemetry, frequency analysis, portability and efficient data management through the use of advanced data acquisition system. Wireless mode of the data transmission helped significantly avoid most of the test site modifications, which in turn helped to reduce the overall system implementation cost.
2011-05-17
Journal Article
2011-01-1614
Thomas C. Austin, Pamela Amette, Christopher F. Real, John F. Lenkeit
In response to a growing need for a practical and technically valid method for measuring exhaust sound pressure levels (SPL) of on-highway motorcycles, the SAE Motorcycle Technical Steering Committee has developed Surface Vehicle Recommended Practice J28251, “Measurement of Exhaust Sound Pressure Levels of Stationary On-Highway Motorcycles,” which includes a new stationary sound test procedure and recommendations for limit values. Key goals of the development process included: minimal equipment requirements, ease of implementation by non-technical personnel, and consistency with the federal EPA requirements; in particular, vehicles compliant with the EPA requirements should not fail when assessed using J2825. Development of the recommended practice involved a comprehensive field study of 25 motorcycles and 76 different exhaust systems, ranging from relatively quiet OEM systems to unbaffled, aftermarket exhaust systems.
2011-05-17
Journal Article
2011-01-1613
Paul R. Donavan
With increasing use of the constant speed pass-by conditions to capture the noise generated by this portion of the vehicle operating cycle, knowledge of the contributing sources of noise was become increasingly important. For frequencies above 400 Hz, the noise is dominated by tire/pavement noise as can be demonstrated by comparing on-board sound intensity (OBSI) measurements to constant speed pass-by noise levels. At lower frequencies, direct on-board measurements become more difficult as the tire/pavement noise source strength decreases with decreasing frequency and microphone induced wind noise increases. To investigate the contribution of sources at these lower frequencies, cruise and coast pass-by measurements were made for a number of different pavement types and two different tire designs at test speeds of 56, 72, and 97 km/h over a frequency range from 50 to 10,000 Hz. OBSI measurements were also conducted for these same conditions.
2011-05-17
Technical Paper
2011-01-1608
Todd Freeman, Gabriella Cerrato
Design parameters for automotive components can be highly affected by the requirements imposed for vehicle pass-by compliance. The key systems affecting pass-by performance generally include the engine, tires, intake system, and exhaust system. The development of these systems is often reliant on the availability of prototype hardware for physical testing on a pass-by course, which can lead to long and potentially costly development cycles. These development cycles can benefit significantly from the ability to utilize analytical data to guide development of component-level design parameters related to pass-by noise. To achieve this goal, test and analysis methods were developed to estimate the vehicle-level pass-by performance from component level data, both from physical and/or analytical sources. The result allows for the estimation of the overall vehicle-level pass-by noise along with the contributions to the total and dominant frequency content from each of the key noise sources.
2011-05-17
Technical Paper
2011-01-1610
Jacobus Huijssen, Raphael Hallez, Bert Pluymers, Stijn Donders, Wim Desmet
Prediction of the drive-by noise level in the early design stage of an automotive vehicle is feasible if the source signatures and source-receiver transfer functions may be determined from simulations based on the available CAD/CAE models. This paper reports on the performance of a drive-by noise synthesis procedure in which the transfer functions are numerically evaluated by employing the Fast Multipole Boundary Element Method (FMBEM). The proposed synthesis procedure first computes the steady-state receiver contributions of the sources as appearing from a number of vehicle positions along the drive path. In a second step, these contributions are then combined into a single transient signal from a moving vehicle for each source-receiver pair by means of a travel time correction.
2011-05-17
Technical Paper
2011-01-1609
Karl Janssens, Pieter Aarnoutse, Peter Gajdatsy, Laurent Britte, Filip Deblauwe, Herman Van der Auweraer
This paper presents a new time-domain source contribution analysis method for in-room pass-by noise. The core of the method is a frequency-domain ASQ model (Airborne Source Quantification) representing each noise generating component (engine, exhaust, left and right tyres, etc.) by a number of acoustic sources. The ASQ model requires the measurement of local FRF's and acoustic noise transfer functions to identify the operational loads from nearby pressure indicator responses and propagate the loads to the various target microphones on the sides of the vehicle. Once a good ASQ model is obtained, FIR filters are constructed, allowing a time-domain synthesis of the various source contributions to each target microphone. The synthesized target response signals are finally recombined into a pass-by sound by taking into account the speed profile of the vehicle.
2011-05-17
Technical Paper
2011-01-1620
Anna Graf, David Lepley, Sivapalan Senthooran
For most car manufacturers, aerodynamic noise is becoming the dominant high frequency noise source (≻ 500 Hz) at highway speeds. Design optimization and early detection of issues related to aeroacoustics remain mainly an experimental art implying high cost prototypes, expensive wind tunnel sessions, and potentially late design changes. To reduce the associated costs as well as development times, there is strong motivation for the development of a reliable numerical prediction capability. This paper presents a computational approach that can be used to predict the vehicle interior noise from the greenhouse wind noise sources, during the early stages of the vehicle developmental process so that design changes can be made to improve the wind noise performance of the vehicle.
2011-05-17
Technical Paper
2011-01-1622
Ray Helferty, Walid Omar, Philip Weber
Expandable cavity sealers have become a critical component of the overall acoustic package that contributes to the documented noise reduction in passenger car applications over the course of the last twenty years. They encompass a variety of technologies, some of which are delivered into the supply chain as bulk materials and others which are highly engineered parts and assemblies. As the market for smaller and more fuel efficient vehicles continues to expand, design architectures of the base vehicle platforms are evolving to include body designs with smaller spaces between adjacent layers of sheet metal. As this space, or cavity, between the adjacent layers of sheet metal is shrinking, the complexity of components that must be integrated into the space between these layers of steel is increasing. Complex arrays of airbags, corresponding wire harnesses, and water management tools are now standard requirements in the design process.
2011-05-17
Technical Paper
2011-01-1617
T.S. Miller, S.W. Lee, G. Holup, J.M. Gallman, M.J. Moeller
The turbulent boundary layer (TBL) that forms on the outer skin of the aircraft in flight is a significant source of interior noise. However, the existing quiet test facilities capable of measuring the TBL wall pressure fluctuations tend to be at low Mach numbers. The objective of this study was to develop a new inlet for an existing six inch square (or 6×6) flow duct that would be adequately free from facility noise to study the TBL wall pressure fluctuations at higher, subsonic Mach numbers. First, the existing flow duct setup was used to measure the TBL wall pressure fluctuations. Then the modified inlet was successfully used to make similar measurements up to Mach number of 0.6. These measurements will be used in the future to validate wall pressure spectrum models for interior noise analysis programs such as statistical energy analysis (SEA) and dynamic energy analysis (DEA).
2011-05-17
Technical Paper
2011-01-1618
George Chaoying Peng
Automotive manufactures demand early assessment of vehicle form design against wind noise attribute to eliminate any engineering waste induced by late design changes. To achieve such an assessment, it is necessary to determine a measurable quantity which is able to represent vehicle form changes, and to understand the relationship between the quantity and vehicle interior cabin noise. This paper reports experimental measurements of vehicle exterior surface pressure and the interior cabin noise level in response to the change of exterior rear view mirror shape. Measurements show that exterior surface pressure on vehicle greenhouse panel is a primary factor of wind noise load to the interior cabin noise; they can be used in preliminary wind noise ranking. Care should be taken when using them in ranking vehicle form wind noise performance. It has been observed that a change in surface pressure on the front side window does not necessarily lead to a change in the interior cabin noise.
2011-05-17
Technical Paper
2011-01-1640
Daniel J. Maguire PhD, Kathleen Reilly, Christian Carme PhD
Active noise control (ANC) has been established as an effective way of addressing low frequency tonal noise in a weight-effective manner. The noise signature of a diesel locomotive cabin suggests that it is a good candidate for ANC. While often true, the production integration of ANC in a working locomotive has challenges extending well beyond laboratory demonstrations. This paper describes an ANC product developed as an aftermarket treatment for a particular model of fleet locomotive including locomotive passive treatment needs, control methods motivated by cabin acoustics, space and safety requirements, as well as logistical demands for testing and deployment.
2011-05-17
Journal Article
2011-01-1641
Claudio Bertolini, Luca Guj
The Diffuse Field Absorption Coefficient (DFAC) is a physical quantity very often used in the automotive industry to assess the performance of sound absorbing multilayers. From a theoretical standpoint, such quantity is defined under rather ideal conditions: the multilayer is assumed to be infinite in extent and the exciting acoustic field is assumed to be perfectly diffuse. From a practical standpoint, in the automotive industry the DFAC is generally measured on samples having a relatively small size (of the order of 1m2) and using relatively small cabins (in the order of 6-7 m₃). It is well known that both these factors (the finite size of the sample and the small volume of the cabin) can have an influence on the results of the measurements, generating deviations from the theoretical DFAC.
2011-05-17
Technical Paper
2011-01-1634
Michael Dinsmore, Richard Bliton, Scott Perz
Using advanced, multi-layer poro-elastic acoustical material modeling technologies, an example of acoustical performance optimization of an underhood sound absorber application is presented. In this case, a porous facing in combination with a fibrous sound absorber pad is optimized for maximum efficiency, which allows for dramatic reduction in pad density and weight. Overall sound absorption performance is shown to be equal or improved versus frequency relative to the incumbent design.
2011-05-17
Technical Paper
2011-01-1637
Ahad Khezerloo, Amin owhadi Esfahani PhD, Sina Jalily lng
One of important problems in railway transportation systems is control of noise and vibration. Metal foams are very good medias for absorbing noise. So in this paper, noise of motion of a train is simulated by MATLAB software and the reduction of noise level in a compartment of passenger car that is equipped by metal foam sheets is considered. Commonly, the sound absorption coefficients are obtained experimentally and they are available in datasheets and references. The different parameters that influence on the capability of this equipment were considered. For example the microstructure, thickness, magnitude of compaction, relative density and etc of metal foam is effective parameters. High porosity has good effect on the performance of absorber sheet. By increasing of compaction ratio, in frequency domain we will have enhancing of absorption of the noise. Compaction process is done by two different ways: one is direct and else is progressively.
2011-05-17
Technical Paper
2011-01-1565
Jennifer Durfy, Sang-Bum Hong, Bibhu Mahanta
As fuel prices continue to be unstable the drive towards more fuel efficient powertrains is increasing. For engine original equipment manufacturers (OEMs) this means engine downsizing coupled with alternative forms of power to create hybrid systems. Understanding the effect of engine downsizing on vehicle interior NVH is critical in the development of such systems. The objective of this work was to develop a vehicle model that could be used with analytical engine mount force data to predict the vehicle interior noise and vibration response. The approach used was based on the assumption that the largest contributor to interior noise and vibration below 200 Hz is dominated by engine mount forces. An experimental transfer path analysis on a Dodge Ram 2500 equipped with a Cummins ISB 6.7L engine was used to create the vehicle model. The vehicle model consisted of the engine mount forces and vehicle paths that define the interior noise and vibration.
2011-05-17
Technical Paper
2011-01-1569
Andrzej Pietrzyk
A broad measurement campaign was run at Volvo aiming at the evaluation of dispersion in test-based NVH characteristics of a car body and at the derivation of reference data for judging the accuracy of CAE predictions. Within this work 6, nominally identical, vehicles were tested. Tests included operational noise on Complete Vehicle (CV) level (road noise, engine noise and idling noise), NTF, VTF & Acoustic FRF measurements in CV, Trimmed Body (TB) & TB-Stripped (TBS) configurations. Additionally, modal analysis and NTF, VTF, AFRF tests were carried out on 4 BIPs of the same vehicle type. Further, limited tests were carried out on 28 vehicles of the same type. The aim of the work was to study the development of dispersion with increasing complexity of the test object, from the BIP to TB and CV.
2011-05-17
Technical Paper
2011-01-1566
Thomas Reinhart, Mitchel Smolik
Several new or significantly upgraded heavy duty truck engines are being introduced in the North American market. One important aspect of these new or revised engines is their noise characteristics. This paper describes the noise related characteristics of the new DD15 engine, and compares them to other competitive heavy truck engines. DD15 engine features relevant to noise include a rear gear train, isolated oil pan and valve cover, and an amplified high pressure common rail fuel system. The transition between non-amplified and amplified common rail operation is shown to have a significant noise impact, not unlike the transition between pilot injection and single shot injection in some other engines.
2011-05-17
Technical Paper
2011-01-1576
Stefan Bernsteiner, Daniel Wallner
Experimental researches on brake squeal have been performed since many years in order to get an insight into friction-excited vibrations and squeal triggering mechanisms. There are many different possibilities to analyse brake squeal. The different operating deflection shapes can be detected using e.g. laser vibrometer systems or acceleration sensors. Piezoelectric load cells can be used for the measurement of the normal contact force of the brake pad. The presented test setup measures not only the mean value of the friction force between brake pad and disc at a certain brake pressure, but also the superposed vibration of this force, which only occurs during a squeal event. Therefore the guide pins of the brake caliper are replaced by modified ones. The brake pads are held in position by these pins and the resulting force of the brake torque, hence the friction force, acts on these pins. The shape of the pins is optimized for measuring these forces.
2011-05-17
Technical Paper
2011-01-1574
Eric Denys
The development and validation of a brake pad insulator damping measurement procedure by the SAE Brake NVH Standards Committee was presented at the 2010 SAE Brake Colloquium (Paper 2010-01-1685). In Europe, in 2010, the EKB Working Group identified the need to develop a similar procedure, and started some activities which lead to the release of a standard similar but different than the SAE J3001. The SAE and EKB working groups agreed that having a global standard was of paramount importance, so the 2 groups decided to meet in November of 2010 to flush out the details of the J3001 global procedure. The details of the new test procedure, test setup and recommendation for proper test practices are described in this paper. This description provides an excellent foundation for evaluating the insulator damping properties over a range of temperatures and frequencies.
2011-05-17
Technical Paper
2011-01-1573
Wen L. Li
A general numerical method, the so-called Fourier Spectral Element Method (FSEM), is described for the dynamic analysis of complex systems such as car body structures. In this method, a complex dynamic system is viewed as an assembly of a number of fundamental structural components such as beams, plates, and shells. Over each structural component, the basic solution variables (typically, the displacements) are sought as a continuous function in the form of an improved Fourier series expansion which is mathematically guaranteed to converge absolutely and uniformly over the solution domain of interest. Accordingly, the Fourier coefficients are considered as the generalized coordinates and determined using the powerful Rayleigh-Ritz method. Since this method does not involve any assumption or an introduction of any artificial model parameters, it is broadly applicable to the whole frequency range which is usually divided into low, mid, and high frequency regions.
2011-05-17
Technical Paper
2011-01-1585
P.J. Shorter, V. Cotoni, S. Chaigne, R.S. Langley
This paper discusses the development of a computationally efficient numerical method for predicting the acoustics of rattle events upfront in the design cycle. The method combines Finite Elements, Boundary Elements and SEA and enables the loudness of a large number of rattle events to be efficiently predicted across a broad frequency range. A low frequency random vibro-acoustic model is used in conjunction with various closed form analytical expressions in order to quickly predict impact probabilities and locations. An existing method has been extended to estimate the statistics of the contact forces across a broad frequency range. Finally, broadband acoustic radiation is predicted using standard low, mid and high frequency vibro-acoustic methods and used to estimate impact loudness. The approach is discussed and a number of validation examples are presented.
2011-05-17
Technical Paper
2011-01-1583
Naga Narayana
Increasing sound quality with advanced audio technology has raised the bar for perceived quality targets for minimal interior noise and maximal speaker sound quality in a passenger vehicle. Speaker-borne structural vibrations and the associated squeak and rattle have been among the most frequent concerns in the perceived audio quality degradation in a vehicle. Digital detection of squeak and rattle issues due to the speaker-borne structural vibrations during the digital vehicle development phase has been a challenge due to the physical complexity involved. Recently, an effective finite element method has been developed to address structure-borne noise [1] and has been applied for detecting the issues of squeak and rattle in passenger vehicles due to vehicle-borne vibrations at vehicle, component and subcomponent levels [2, 3, 4, 5, 6, 7, 8].
2011-05-17
Technical Paper
2011-01-1591
Kumbhar S. Mansinh, Atul Miskin, Vishal Vasantrao Chaudhari, Ashish Rajput
The noise and vibration performance of diesel fueled automotives is critical for overall customer comfort. The stationary vehicle with engine running idle (Vehicle Idle) is a very common operating condition in city driving cycle. Hence it is most common comfort assessment criteria for diesel vehicles. Simulations and optimization of it in an early stage of product development cycle is priority for all OEMs. In vehicle idle condition, powertrain is the only major source of Noise and Vibrations. The key to First Time Right Idle NVH simulations and optimization remains being able to optimize all Transfer paths, from powertrain mounts to Driver Ear. This Paper talks about the approach established for simulations and optimization of powertrain forces entering in to frame by optimizing powertrain mount hard points and stiffness. Powertrain forces optimized through set process are further used to predict the vehicle passenger compartment noise and steering vibrations.
2011-05-17
Technical Paper
2011-01-1604
Zhi-yong Chen, Guang-ming Wu, Wen-ku Shi, Qing-guo Wang, Teng Teng
Hyperelastic model constants of rubber material are predicted based on test date. The fluid-structure interaction model of light vehicle cab's hydraulic mount is established. Static characteristics of the hydraulic mount are analyzed by quasi-static method. In dynamic characteristics analysis, the flow model of fluid is set to turbulent K-Epsilon RNG. The dynamic stiffness and loss angle of the hydraulic mount are presented via the finite element model. The simulations of static and dynamic characteristics agree well with corresponding test results. The effects of main structure parameters to the dynamic characteristics of the hydraulic mount are analyzed based on the finite element model.
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