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Viewing 1 to 30 of 42208
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
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
2011-01-1611
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
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
2011-01-1620
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
2011-01-1633
Chong Wang, Alan Parrett
The primary function of damping treatment on a vibrating panel in a vehicle is to reduce vibration levels or radiated sound power by the dissipation of energy. However, in automotive applications the mass effects of damping materials should not be ignored, especially with regard to airborne noise performance. In this paper, a Finite Element-Statistical Energy Analysis (FE-SEA) hybrid analysis is used to evaluate the mass effects of applied damping materials on Sound Transmission Loss (STL). The analysis takes into consideration effects on both the elastic properties and modal mass of the panel. It is shown that while uniformly distributing the mass of the damping material over the panel generally over-estimate the mass effects on STL, an area weighting approach underestimates the effects. Results are confirmed by laboratory testing. A nomogram is generated to show the total effect of the mass of the damping material on STL.
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
2011-01-1565
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
2011-01-1576
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
2011-01-1594
Emiel Tijs, Jelmer Wind, Daniel Fernández Comesaña
All surfaces of a cabin interior may contribute to the sound pressure at a certain reference position, e.g. the human's ear. Panel noise contribution analysis (PNCA) involves the measurement of the contribution of separate areas. This is an effective method to determine the effect of apparent noise sources at a specific location. This paper presents the latest developments on particle velocity based panel noise contribution analysis. In contrast to the traditional methods, the particle velocity approach is faster; it requires 3 days instead of weeks. While the theoretical base of the procedure in this paper is similar to previously published particle velocity based procedure, here the measurement protocol has now been simplified dramatically, which has reduced the measurement time even more to less than a day. The method and its implementation are explained in the paper and a full measurement procedure is reported.
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
2011-01-1599
Dhanaji Kalsule, David Hudson, Yogesh Yeola, Jakir Bohari
Among the key parameters that decide the success of a vehicle in today's competitive market are quietness of passenger cabin (in respect of both airborne and structure-borne noise) and low levels of disturbing vibration felt by the occupants. To control these values in body-on-frame construction vehicles, it is necessary to identify major transfer paths and optimize the isolation characteristics of the elastomeric mounts placed at several locations between a frame and the enclosed passenger cabin of the vehicle. These body mounts play a dominant role in controlling the structure-borne noise and vibrations at floor and seat rails resulting from engine and driveline excitations, and they are also a vital element in the vehicle ride comfort tuning across a wide frequency range. In the work described in this paper, transfer path tracking was used to identify root cause for the higher noise and vibration levels of a diesel-powered sports utility vehicle.
2011-05-17
Technical Paper
2011-01-1600
Theo Geluk, Peter Van der Linden, Davide Vige', Massimo Caudano, Simone Gottardi, Fabio Ciraolo, Hamid Mir
Road-tire induced vibrations are in many vehicles determining the interior noise levels in (semi-) constant speed driving. The understanding of the noise contributions of different connections of the suspension systems to the vehicle is essential in improvement of the isolation capabilities of the suspension- and body-structure. To identify these noise contributions, both the forces acting at the suspension-to-body connections points and the vibro-acoustic transfers from the connection points to the interior microphones are required. In this paper different approaches to identify the forces are compared for their applicability to road noise analysis. First step for the force identification is the full vehicle operational measurement in which target responses (interior noise) and indicator responses (accelerations or other) are measured.
2011-05-17
Technical Paper
2011-01-1595
Rajesh Bhangale, Kumbhar S. Mansinh
Recent development in automobile industries has seen increased customer attention for good door slamming noise. One of the constituent which plays major role in building brand image of vehicle in terms of NVH performance is door slam noise quality. Hence it is very desirable to understand how different door elements radiate sound during a door-closing event and how to optimize a door structure to achieve specific sound target in order to ensure the door closing noise quality, NVH engineers needed to look at contributions from different door subsystems. The use of statistical tools like Six Sigma can further help them to ensure the consistency in results. This paper explains the systematic approach used to characterize different element of door which contributes to the overall door slam noise quality through QFD (Quality Function Deployment) and contribution analysis. The different mechanisms contributing to door slam noise were studied.
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.
2011-05-17
Journal Article
2011-01-1602
Christopher Hartley
Understanding the resonant behavior of vehicle closures such as doors, hoods, trunks, and rear lift gates can be critical to achieve structure-borne noise, vibration, and harshness (NVH) performance requirements, particularly below 100Hz. Nearly all closure systems have elastomer weatherstrip components that create a viscoelastic boundary condition along a continuous line around its perimeter and is capable of influencing the resonant behavior of the closure system. This paper outlines an approach to simulate the static and dynamic characteristics of a closed-cell Ethylene Propylene Diene Monomer (EPDM) foam rubber weatherstrip component that is first subjected to a large-strain quasi-static preload with a small-strain sinusoidal dynamic load superimposed. An outline of a theoretical approach using “phi-functions” as developed by K.N. Morman Jr., and J.C.
2011-05-17
Technical Paper
2011-01-1528
Deepak Rana, Felix Regin, Mohan Makana
A muffler or silencer is an integral part of the exhaust system and is a device used to prevent sound from reaching the openings of the exhaust duct and radiating as far field noise. Different acoustical design and analysis techniques are used to predict the acoustical performance of exhaust systems. Flow noise from exhaust tail pipe is one of the major noise sources in a vehicle. Flow noise is generated mainly during fast acceleration operating condition due to complex flow behavior. In this paper, we have studied the detailed flow field and tried to establish an analyses procedure for flow noise prediction. The flow analysis is carried out in commercial CFD solver Star CCM+. The transient engine boundary conditions are obtained from the experimental testing. The flow noise generated from the muffler was calculated by acoustic analogy of Lighthill using the above boundary conditions.
2011-05-17
Journal Article
2011-01-1527
Rick Dehner, Ahmet Selamet, Philip Keller, Michael Becker
The unsteady surge behavior of a turbocharger compression system is studied computationally by employing a one-dimensional engine simulation code. The system modeled represents a new turbocharger test stand consisting of a compressor inlet duct breathing from ambient, a centrifugal compressor, an exit duct connected to an adjustable-volume plenum, followed by another duct which incorporates a control valve and an orifice flow meter before exhausting to ambient. Characteristics of mild and deep surge are captured as the mass flow rate is reduced below the stability limit, including discrete sound peaks at low frequencies along with their amplitudes in the compressor (downstream) duct and plenum. The predictions are then compared with the experimental results obtained from the cold stand placed in a hemi-anechoic room.
2011-05-17
Journal Article
2011-01-1529
Zhenlin Ji, Zhi Fang
The one-dimensional analytical approach, three-dimensional finite element method (FEM) and boundary element method (BEM) are developed to predict and analyze the acoustic attenuation performance of three-pass perforated tube muffler with end-resonator. For an elliptical muffler, the predictions of transmission loss from the FEM and BEM agree well each other throughout the frequency range of interest, while the one-dimensional analytical solution shows a reasonable agreement with the numerical predictions at lower frequencies and deviates at higher frequencies. The FEM is then used to investigate the effects of geometrical parameters and internal structure on the acoustic attenuation performance of three-pass perforated tube muffler with end-resonator.
2011-05-17
Technical Paper
2011-01-1532
Charlie Teng, Fumin Pan, Jemai Missaoui, Scott Deraad
Turbocharged gasoline engines are typically equipped with a compressor anti-surge valve or CBV (compressor by-pass valve). The purpose of this valve is to release pressurized air between the throttle and the compressor outlet during tip-out maneuvers. At normal operating conditions, the CBV is closed. There are two major CBV mounting configurations. One is to mount the CBV on the AIS system. The other is to mount the CBV directly on the compressor housing, which is called an integrated CBV. For an integrated CBV, at normal operating conditions, it is closed and the enclosed passageway between high pressure side and low pressure side forms a “side-branch” in the compressor inlet side (Figure 12). The cavity modes associated with this “side-branch” could be excited by shear layer flow and result in narrow band flow noises.
2011-05-17
Journal Article
2011-01-1534
Wen-BIn Shangguan
Experimental methods for measuring static and dynamic characteristics of an engine Frond End Accessory Drive System (FEADS) are presented. The static performance of a FEADS is the static tension of the belt, and the dynamic properties of a FEADS are transverse vibration of belt, and rotational vibration performances that include rotational response of pulleys and tensioner arm, dynamic tension of belt span, slip factor between belt and pulley. A mathematical model and calculation method for rotational vibration analysis of a 8 pulley-belt FEADS is established. In the model, creeping effect of a belt on pulley wrap arc, viscous damping and dry friction of a tensioner are considered. In calculation of dynamic performances of the FEADS, the excitation torques with multi-frequency components from crankshaft torsional vibration are obtained from the measurement.
2011-05-17
Technical Paper
2011-01-1535
Christopher Edward Baker, Homer Rahnejat, Ramin Rahmani PhD, Stephanos Theodossiades
Piston compression rings are thin, incomplete circular structures which are subject to complex motions during a typical 4-stroke internal combustion engine cycle. Ring dynamics comprises its inertial motion relative to the piston, within the confine of its seating groove. There are also elastodynamic modes, such as the ring in-plane motions. A number of modes can be excited, dependent on the net applied force. The latter includes the ring tension and cylinder pressure loading, both of which act outwards on the ring and conform it to the cylinder bore. There is also the radial inward force as the result of ring-bore conjunctional pressure (i.e. contact force). Under transient conditions, the inward and outward forces do not equilibrate, resulting in the small inertial radial motion of the ring.
2011-05-17
Technical Paper
2011-01-1544
Vittorio Ravaglioli, Fabrizio Ponti, Federico Stola
This paper presents the results of several studies, performed on different powertrain configurations, aimed at analyzing the correlations existing between torque and speed frequency components in an internal combustion engine. Engine speed fluctuations depend in fact on torque delivered by each cylinder, therefore it is easy to understand how these two quantities are directly connected. The presented methodology allows identifying a dynamic model, expressed as a transfer function that depends only on the structure of the engine-driveline system. The identified model can be used to obtain information about torque delivered by the engine and combustion positioning within the engine cycle starting from engine speed measurement. The speed signal is picked up directly from the sensor facing the toothed wheel that is already mounted on the engine for control purposes.
2011-05-17
Journal Article
2011-01-1550
Wei Sun, Yinong Li, Jingying Huang
Dual Mass Flywheel (DMF) has better damping capacity than the conventional Clutch Torsional Damper (CTD), and is more suitable for diesel engine, Dual Clutch Transmission (DCT) and hybrid vehicles. Dual Mass Flywheel-Radial Spring (DMF-RS) is a DMF that has a specific structure. In the light of working principal and static analysis, the hard nonlinear torsional stiffness of DMF-RS is derived in this paper, which is very important to a driveline damper. On this basis, a simulation model is developed to analyze the dynamic response of DMF and CTD excited by idle engine; the comparison of the two dampers reveals that the DMF has better damping capacity, high-frequency filter ability and can reduce crankshaft load.
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