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Viewing 1 to 30 of 7117
2010-10-25
Technical Paper
2010-01-2162
Patricia Anselmi, Julian Kashdan, Guillaume Bression, Edouard Ferrero-Lesur, Benoist Thirouard, Bruno Walter
Latest emissions standards impose very low NOx and particle emissions that have led to new Diesel combustion operating conditions, such as low temperature combustion (LTC). The principle of LTC is based on enhancing air fuel mixing and reducing combustion temperature, reducing raw nitrogen oxides (NOx) and particle emissions. However, new difficulties have arisen. LTC is typically achieved through high dilution rates and low CR, resulting in increased auto-ignition delay that produces significant noise and deteriorates the combustion phasing. At the same time, lower combustion temperature and reduced oxygen concentration increases hydrocarbon (HC) and carbon oxide (CO) emissions, which can be problematic at low load. Therefore, if LTC is a promising solution to meet future emission regulations, it imposes a new emissions, fuel consumption and noise trade-off. For this, the injection strategy is the most direct mean of controlling the heat release profile and fuel air mixture.
2010-09-28
Technical Paper
2010-32-0028
Daniela Siano, Fabio Auriemma PhD, Fabio Bozza
Automotive exhaust systems give a major contribution to the sound quality of a vehicle and must be properly designed in order to produce acceptable acoustic performances. Obviously, noise attenuation is strictly related to the used materials and to its internal geometry. This last influences the wave propagation and the gas-dynamic field. The purpose of this paper is to describe advantages and disadvantages of different numerical approaches in evaluating the acoustic performance in terms of attenuation versus frequency (Transmission Loss) of a commercial two perforated tube muffler under different conditions. At first, a one-dimensional analysis is performed through the 1D GTPower® code, solving the nonlinear flow equations which characterize the wave propagation phenomena. The muffler is characterized as a network of properly connected pipes and volumes starting from 3D CAD information. Then, two different 3D analyses are performed within the commercial STS VNOISE® code.
2010-09-28
Technical Paper
2010-32-0027
Darrell A. Wiatrowski, Peter E. Lucier
Advances in motorized vehicle vibration control have increased consumer expectations to feel minimal vibration when operating vehicles in any environment; on and off road. Small outboard marine engines have a heightened need for vibration isolation, since the user often steers using a tiller arm connected to the outboard. Traditional engine mount systems allow the mount reaction loads to create a periodic torque about the steering axis and result in significant tiller arm shaking forces. This paper presents a novel mount arrangement that minimizes the shaking couple about the steering axis and isolates the tiller from engine vibration. The concept was first modeled using rigid body dynamics software to predict vibration of the tiller arm. Testing confirmed the simulation, and demonstrated a significant reduction of vibration transmitted to the tiller arm and boat seat compared with a traditional focused mount system.
2010-09-28
Technical Paper
2010-32-0025
Masao Ishihama
This paper reports development of a measuring device built in a camshaft drive chain sprocket for detecting precise torque fluctuation with minimum change on the valve drive system dynamical characteristics. This torque measuring device (TMD) was designed to measure torque with minimum cross-talk with bending force or lateral force. To realize these functions, the disc portion of a chain sprocket that connects the teeth and the camshaft was carved to make thin plate area so that the strain gages placed on the area may have enough sensitivity to torque fluctuation. The signal from the circuit goes through frequency modulation and is transmitted to demodulation circuit via coil antennas. By this arrangement, almost perfect linearity was observed in the relationship of the TMD output voltage and the applied torque. Using a model cylinder head unit of an in-line four cylinder gasoline engine driven by a variable speed electric motor, the TMD performance was evaluated.
2010-09-28
Technical Paper
2010-32-0023
Toshiaki Taguchi, Makoto Aoki, Youta Katsukawa, Masahiro KOGA, Tohru Koshimizu, Masahito Saitou
Motorcycle exhaust mufflers are important devices which influence not only exhaust noise and engine performance but also appearance of motorcycle. Since the improvement of engine performance often contradicts the attenuation of exhaust noise in designing mufflers, it is necessary that both the exhaust noise and the engine performance are predicted simultaneously. Recently, unsteady-state one-dimensional computational fluid dynamics (1-D CFD) analysis is being applied to this problem. We have developed the technique to predict engine performance and exhaust pulsating sound by adopting unsteady-sate 1-D CFD analysis (here, we treat the exhaust pulsating sound which is a discrete frequency component of exhaust noise). In this paper, firstly, as a result of a preliminary study, it is shown that our prediction technique can predict the acoustic transmission loss of a muffler.
2010-09-28
Technical Paper
2010-32-0022
Jüri Lavrentjev, Hans Rämmal
Today, catalytic converters are widely used in small engine exhaust systems to reduce pollutants. Besides reducing harmful pollutants, these devices have a significant effect on the acoustical performance and the pressure drop of the engine exhaust system. A catalytic converter is known to have two distinct acoustic effects: the reactive effect originating from the acoustic wave reflections caused by cross-sectional area changes within the unit and the resistive effect which results in the acoustic wave dissipation caused by viscous losses. The pressure drop in the narrow tubes in the catalytic converter element results in frequency dependent resistive effects on the transmitted sound. In this paper the passive acoustic effect which treats the sound attenuation in the catalytic converters has been investigated. An experimental investigation on small engine catalytic converters treated as acoustic two-ports is carried out.
2010-04-12
Technical Paper
2010-01-0586
Avoki Michel Omekanda, Todd Geib, Dan Buehler, Kirk Wan, Lucille G. Lavan
Gasoline Direct Injection (GDi) system is a relatively new technology. In early implementations, its major components, i.e. high pressure fuel pump, injectors, and fuel rails, emit objectionable acoustic noise during normal operation. This paper will focus on making an objective comparison (assessment) of acoustic noise emitted by several cam-driven high pressure fuel pumps during their normal operation, especially at engine idle. Taguchi robust engineering methods will be used to conduct the robust assessment study of six GDi high-pressure pumps. A-weighted total sound pressure level (SPL), processed from two free-field microphones around each pump, will be used as the main function in the Taguchi design of experiments (DOE).
2010-04-12
Technical Paper
2010-01-0414
Avnish Gosain, Mugundaram Ravindran
One of the most common NVH refinement areas of a vehicle is the cabin booming noise. The current study discusses the improvement of the low frequency booming noise in the cabin of a small passenger car. The practice of reinforcing experimental evaluation results with the extensive use of computer aided engineering tools in the development process is presented in this paper. The structural changes executed in the vehicle, to reduce noise contribution, are iterated and optimized using simulation and validated using experimental analysis methods like operational modal analysis, linear frequency response functions and actual run-up measurements. Additionally, the interesting variation of the NVH characteristics of a vehicle due to the changeover from a 4-cylinder inline to a 3-cylinder inline powertrain, while inheriting the similar body structure, is discussed in this study.
2010-04-12
Technical Paper
2010-01-0416
Weiguo Zhang, S. T. Raveendra, Moohyung Lee, J Stuart Bolton
The identification of the propulsion noise of turbofan engines plays an important role in the design of low-noise aircraft. The noise generation mechanisms of a typical turbofan engine are very complicated and it is not practical, if not impossible, to identify these noise sources efficiently and accurately using numerical or experimental techniques alone. In addition, a major practical concern for the measurement of acoustic pressure inside the duct of a turbofan is the placement of microphones and their supporting frames which will change the flow conditions under normal operational conditions. The measurement of acoustic pressures on the surface of the duct using surface-mounted microphones eliminates this undesirable effect. In this paper, a generalized acoustical holography (GAH) method that is capable of estimating aeroacoustic sources using surface sound pressure is developed.
2010-04-12
Technical Paper
2010-01-1141
Yong Woo Park, Hyo Seok Kim, Kwangjin Joo, Namil Jeon
The purpose of this paper is to identify and reduce the suspension rattle noise. First, the characteristics of the rattle noise are analyzed experimentally in the time and frequency domain. It was found that the rattle noise and vibration at shock absorber mounting point are strongly correlated. Second, the sensitivity analysis of design parameters is performed using a half car model in ADAMS. The result of the simulation model is verified by comparison with test. Finally, the influence of design parameters for the rattle noise is investigated. The study shows that the shock absorber mounting bushing is the most sensitive parameter to affect the suspension rattle noise. This paper shows how the suspension rattle noise can be improved.
2010-04-12
Technical Paper
2010-01-1094
Shin Nishimura, Takashi Tetsuka, Yukihiro Asada, Tomoya Kono, Makoto Tsuyuguchi, Satoru Nojima
Honda R&D has developed a throttle-by-wire (TBW) system that meets the needs of motorcycles where the attitude of the vehicle body is controlled by operation of the throttle. To gain high response and following for the throttle valve, we employed a new adaptive control algorithm. The newly developed system has an idling combustion stabilization function and a three-dimensional control function for the throttle-opening map based on running gear and engine speed. With those functions, we improved the controllability of the motorcycle, especially for small throttle openings. Furthermore, we improved the feeling of the limiter control used in maximum-speed limitation. For the overall system, intake system related devices are consolidated to improve the layout flexibility and expand the mounting options on the motorcycle.
2010-10-10
Technical Paper
2010-01-1685
Eric Denys, James K. Thompson
The development and validation of a brake pad insulator damping measurement procedure by the SAE Brake NVH Standards Committee is described in this paper. The details of the test procedure, test set-up and recommendations for proper test practices are described. The description provides an excellent foundation for evaluating the damping properties of a shim over a range of frequencies and temperatures. To document the repeatability of the measurement process, a Gage R&R study was conducted. The results show that a high level of repeatability is achieved over a range of temperatures and damping properties. An example application is described to illustrate the usage of the procedure. This example provides an excellent illustration of how this procedure can be used to select the best shim for a specific application. Conclusions as to the applicability of this procedure and its value to brake noise control are provided in the final section.
2010-10-10
Technical Paper
2010-01-1686
Carmen Parra, Jose Luis Olazagoitia, Jorge Biera
Coalescence of natural frequencies among different brake components is one of the main causes for squeal noise appearance under some specific operating conditions. Many publications have dealt with the study of squealing under different situations. However, in most cases this knowledge has not been transferred to the companies by means of easy to use software. This paper is focused on the development of a practical tool to provide brake pad manufacturers with an instrument to reduce the probability to suffer squeal noises at the design stage of the product. It can also be used as a problem solving tool to interactively find the optimum design to a specific problem.
2010-10-10
Journal Article
2010-01-1687
Georg P. Ostermeyer, Matthias Graf
To predict and minimize squeal propensity in brake systems, numerous models, which perform friction induced vibration, are available. However, today there is no model that can explain satisfactorily the dynamic behavior of brake systems. We argue that this is - among other effects - because existing models are based on decaying or constant coefficient of friction, although many investigations indicate rich dynamics of the coefficient of friction. Stability analysis of linear differential equations with periodic coefficients shows that instability regions change with rising amplitude of the periodic coefficients. If the periodic coefficient corresponds to the coefficient of friction, its periodicity can lower the stability of a minimal model.
2010-10-10
Technical Paper
2010-01-1688
Mohamed Khalid Abdelhamid, Eric Denys
As part of the development of a new SAE Recommended Practice for brake rotor modal frequencies measurement and control, the SAE Brake NVH Standards Committee developed detailed recommendations for such measurement, data reporting and use in quality control. This paper addresses the need for formalizing measurement techniques of rotor modal frequencies and documenting the proper set up and measurement parameters. Additionally, a rotor mode classification system is proposed so that important rotor modes may be tracked. Statistical control of modal frequencies is presented and practical limits are defined
2010-10-10
Technical Paper
2010-01-1684
Mohamed Khalid Abdelhamid
NVH development is an important part of modern brake product development plans. This paper analyzes a typical NVH development process and identifies gaps in available development technologies and processes that when filled can improve the brake NVH development effort. The paper also discusses how the disciplines of simulation, component testing, dynamometer testing, and vehicle testing are currently integrated and proposes more effective processes of development. The paper identifies opportunities for contributions from professional societies and standardization organizations, vendors of test equipment and software, test laboratories, university research centers as well as brake suppliers' engineering centers to improve the engineering toolbox and fill the gaps in brake NVH development.
2010-10-10
Technical Paper
2010-01-1695
Mahboob Khan, Korey Johnson, Toby Lichtensteiger, Carly Lockrem
A case study was performed on a motorcycle platform to resolve customer complaint concerning Brake Noise. The Brake Noise was classically characterized in the moan and squeal frequency bands. Brake moan was present on the rear brake system, mostly in reverse, and without brake apply. The primary frequency for moan was in the range of 270 - 280 Hz. Brake squeal was confirmed at multiple frequencies on both the front and rear brakes. The intent of this paper is to present the challenges as well as the correlation of automotive methods and countermeasures to resolve these issues. Modal analysis was performed both experimentally and analytically to establish the correlation and to define the modal coupling of individual and adjacent components. Dynamometer testing was performed experimentally by adapting and evaluating the auto industry noise screening standard procedure SAE J2521 .
2010-10-10
Technical Paper
2010-01-1694
Francisco Bisotto Jardim, Alberto Tamagna
Vehicle brake judder is a vibration phenomenon responsible for an expressive number of customer complaints. In order to prevent judder from occurring, new vehicle developments are putting in practice dynamometer and vehicle brake tests to assess the DTV growth and the effectiveness of applied countermeasures, when necessary. The measurement of DTV is very sensitive and requires high precision sensors. Due to these facts, incorrect DTV measurements are not uncommon, since the rig or vehicle setup, the assembly/disassembly of the sensors or brakes and even the vibration of the dynamometer itself may figure as sources for measurement errors. In the other hand, if the test vehicle or dynamometer is equipped to acquire brake torque and brake pressure variations (BTV and BPV, respectively), those measurements may suffer less interference from external parameters and present good relationship with DTV and judder.
2010-10-10
Technical Paper
2010-01-1696
Mark Riefe, James Thompson, Mark Rogus, Mohamed Abdelhamid
This paper presents the work of the SAE Brake NVH Standards Committee in developing a draft Low-Frequency Brake Noise Test Procedure. The goal of the procedure is to be able to accurately measure noise issues in the frequency range below 900 Hz using a conventional shaft brake noise dynamometer. The tests conducted while evaluating alternative test protocols will be discussed and examined in detail. The unique issues encountered in developing a suitable test procedure for low-frequency noise will be discussed, and the results of tests using both shaft brake dynamometers and chassis dynamometers will be described. The current draft procedure incorporating the knowledge gained from this development effort will be described in detail and conclusions as to its applicability will also be presented
2010-10-10
Technical Paper
2010-01-1691
Yoshitsugu Goto, Hidetaka Saomoto, Noboru Sugiura, Toru Matsushima, Satoshi Ito, Akihiro Fukui
The finite element method (FEM) is effective for analyzing brake squeal phenomena. Although FEM analysis can be used to easily obtain squeal frequencies and complex vibration modes, it is difficult to identify how to modify brake structure design or contact conditions between components. Therefore, this study deals with a practical design method using sensitivity analysis to reduce brake squeal, which is capable of optimizing both the structure of components and contact conditions. A series of analysis processes that consist of modal reduction, complex eigenvalue analysis, sensitivity analysis and optimization analysis is shown and some application results are described using disk brake systems.
2010-10-10
Technical Paper
2010-01-1692
Gottfried Spelsberg-Korspeter, Martin Schönecker, Peter Hagedorn
The squealing of disk and drum brakes is still a major problem to design engineers. It has been observed by Fieldhouse and others that the introduction of asymmetries into the brake rotor can lead to a reduction of brake noise. However this insight has not yet solved the squeal problem. One reason for this is that it is not a priori obvious which kind of asymmetries of the rotor are preferable and which ones are not. This lack of knowledge most likely originates from the fact that most models explaining disk brake squeal rely on a symmetric rotor. In this paper, models for disk brake squeal are presented which are suitable to study asymmetric brake rotors. The excitation mechanism for squeal is explained by the formulation of a stability problem. It is shown that multiple eigenfrequencies of the rotor make it extremely sensitive to self-excited vibrations, i.e. squeal.
2010-10-10
Technical Paper
2010-01-1693
Toshikazu Okamura, Hiroyuki Yumoto
Regarding the vibrational characteristics of a brake disc causing brake squeal, there are two factors: eigenmode alignment (or natural frequencies) and damping capacity. Focusing on the effects of dimensions on damping capacity of a brake disc, intensive CAE experiments for analyzing the effects were conducted. It was found that disc damping capacity can be increased independently of natural frequency by modifying disc dimensions. It was also found that peak accelerance obtained from a frequency-response function of a brake disc is an effective parameter for evaluating damping capacity of a brake disc.
2010-05-05
Technical Paper
2010-01-1540
Georges Vretos Glyniadakis, Alexandre Bercelos de Souza, Mauro Miguel Pecula, Marlon Casagrande Rodrigues, Jose Maria Dos Santos
Sound quality requirements have been more often used in light and heavy duty trucks market. Then, vehicle owners fell uncomfortable with rattle noise mainly at idle speed with air compressor operating in load phase. Sometimes they associate this noise as a failure, which can generate a car shop dealer claim, as well as product and company image deterioration. One option to deal with this kind of noise is to apply an anti-backlash gears. The literature shows that as we decrease the backlash the rattle is reduced too. Then, to understand the effect of this solution is mandatory before to apply into production. The object of this work is to study the vibroacoustics effects of the anti-backlash gear system regarding to the air compressor rattle noise of the MWM ACTEON 4.12TCE diesel engine. The angular displacement and velocities fluctuation of the air compressor anti-backlash gear were analyzed in order to characterize the air compressor gear rattle.
2010-05-05
Technical Paper
2010-01-1539
Bin Wang, Xuexun Guo
On road simulation, both the traditional iterative method based on frequency response function (FRF) and adaptive control method based on the CARMA model are realized by using linear model to identify the target test system. However the real test system is very complicated because of various nonlinear factors. Linear models approximately describe the system only in a small range. Therefore, system simulation methods can not be used to validate the developed control algorithm and the uncertainty of test accordingly increases. As mentioned above, this paper presents a model to identify the nonlinear test system using NARMA dynamic neural network and discusses how to make the model parameters in detail. Using the test input-output series data, this network was trained by Levenberg-Marquardt method. Results of verification simulation show the validation of the nonlinear model.
2010-10-10
Technical Paper
2010-01-1712
Daniel Wallner, Stefan Bernsteiner, Wolfgang Hirschberg, Alexander Rabofsky
This paper deals with the analysis of a complete axle of a passenger car, which shows brake squeal in test runs. The complete brake system including the parts of the corner is studied with two different Finite Element Analysis programs and their brake squeal calculation algorithms. Thereby significant differences between the results of the two simulations and also the experiments are observed. The used element type and the chosen discretisation level influence largely the simulated contact and thereby the overall results. In order to explain these outcomes, the force distribution and the force vectors between disc and pad are analysed. On the one hand tetrahedral elements cause stiffening of the parts and hence of the contact. On the other hand the effort to create hexahedral elements in daily meshing practice is often omitted due to cost reasons. This trend is enforced by the statement of software vendors.
2010-10-10
Technical Paper
2010-01-1717
Georg Ostermeyer
There are a few principal excitation mechanisms that brake system NVH simulations are based on, especially the high frequency squeal simulations. These mechanisms can be described by some simple mechanical models that exhibit excitation or self excitation effects induced by friction [ 1 ]. These models use very simple friction laws of Coulomb type, described by a friction coefficient that is either a constant or simple functions of some state variables, taking into account a Stribeck characteristic. Eigenvalues of the linearized models are computed in the frequency domain, and often used to judge the stabilities of the models. Industry applications typically use FEA programs in the modeling, which allows detailed descriptions of the geometry of the brake system, except the friction layer. In the friction layer between brake disk and pad, simple friction laws are used, which allows a modal analysis similar to that of the minimal models.
2010-10-10
Technical Paper
2010-01-1716
Hiroyuki Nonaka, Yukio Nishizawa, Yutaka Kurita, Yasunori Oura
This study aims to incorporate the dynamic stiffness of pads into the finite element method (FEM) used for brake design in order to improve the accuracy of FEM analyses. In the first step, the vibration caused by a disk brake squeal is simulated in order to measure the dynamic stiffness of the brake pads. We then compare this result with the static stiffness result obtained from a past static compressive strain and show that these different modes of stiffness have different characteristics. The dynamic stiffness of the pad is higher than the static stiffness and is greatly dependent on pressure load. The next step is to show, from the squeal experiments using a simple squeal tester and FEM analysis, that it is dynamic stiffness and not static stiffness of the pads that correlates to squeal.
2010-10-10
Technical Paper
2010-01-1715
Kiyotaka Obunai, Sho Hagiwara, Kazuya Okubo, Toru Fujii, Tsuyoshi Nakatsuji
The purpose of this study is to propose an effective model to estimate the excitation force accompanied with stick-slip between shoe and disc, considering the strain distribution on contact surface of the shoe, and then to propose an effective concept to design the brake which reduced the brake squeal under practical use. In order to investigate the influence of configuration of the hole, three types of discs were prepared in which the size of holes was different. The SPL (Sound Pressure Level) and the frequency of squeal for three types of discs were measured when the brake squeal was observed at conditions of low sliding speed. The change of stability of the brake shoe passing on hole was analyzed by 2-D simplified brake system model.
2010-06-09
Technical Paper
2010-01-1424
Hans Rämmal, Mats Åbom, Heiki Tiikoja, Hans Bodén
In this paper a unique experimental facility designed for a complete determination of the sound transmission in turbochargers is introduced. The facility can be used to characterize the passive acoustic effect for turbocharger compressors and turbines working in realistic operating conditions by extracting the acoustic two-port data. The acoustic pressure transmission loss results for a passenger car turbocharger compressor and turbine measured in up- and downstream directions regarding the mean flow are presented. The data are obtained for various operating points of the turbocharger and the influence of operating conditions on the sound transmission is discussed.
2010-06-09
Technical Paper
2010-01-1425
Jan Krueger, M. Pommerer, Rolf Jebasinski
In the past years, Eberspaecher has developed active exhaust silencers for several passenger vehicles with different engines on a prototype level. In general, a substantial reduction of the exhaust noise is regularly achieved in a frequency range of 40 - 400 Hz covering the most relevant engine orders. In exhaust system development the main design conflicts are noise reduction, silencer volume/weight and backpressure. Recent progress was made in the development of the durability and industrialization of the actuator. This component could be reduced in size and weight thus allowing the integration in different design spaces of many vehicles. In some cases, the conventional dual exhaust system can even be replaced by an active single exhaust line without compromising on the acoustic or backpressure targets but saving > 50 % of space and > 30% weight. The potential impact of this technology on future vehicle designs will be discussed.
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