Display:

Results

Viewing 31 to 60 of 9221
2016-04-05
Technical Paper
2016-01-1123
Ante Bozic
Hydrostatic transmissions are well known solutions for of road mobile machines. Main reason for this is balance among compactness, efficiency, control comfort and price. For same reason, several car companies tried to introduce hydrostatic transmissions, into the on-road applications. All such efforts failed,mainly, due to the whine noise, produced by hydrostatic machines. Namely, standard solutions, aimed to deal with hydraulic noise, like notches and/or pre-compression volumes, are oriented toward noise level reduction, in first place, and any sound-quality improvement came as secondary effect. Unfortunately, level of unpleasant whine noise, even with well optimized notches and pre-compression volumes, is unacceptable high. In this article new, inventive, scientifically based, successfully tested, method, aimed to suppress whine noise, of the hydrostatic machines, will be presented. It is based on Pseudo Random Binary Sequence (PRBS).
2016-04-05
Technical Paper
2016-01-1355
Jeffrey R. Hodgkins, Walter Brophy, Thomas Gaydosh, Norimasa Kobayashi, Hiroo Yamaoka
Current CAE (computer aided engineering) methods used to develop vehicle interior noise performances have always had the reputation for being inaccurate in predicting acoustic behavior in the mid-frequency range (300 to 1000 Hz). It is in this frequency range where the overall acoustic performance becomes sensitive to not only the contributions of structure-borne noise components, which CAE has proven capable of predicting, but also the growing contributions of air-borne noise components, where CAE usually lacks the capability to accurately reflect the physics involved in complex vibro-acoustic systems. This paper will discuss a study that was undertaken to test the capability of a finite element modeling method that can accurately simulate air-borne noise phenomena in the mid-frequency range. This modeling method was used to create a model of an enclosed simple box-shaped vibro-acoustic system fit with various acoustic trim parts (carpet and under body covers).
2016-04-05
Technical Paper
2016-01-1114
Jinsung Kim
A dry clutch is vulnerable to judder phenomenon which is caused by variations in the vehicle load condition and frictional material properties. Such a problem may lead to the stick-slip limit cycle that results in undesired longitudinal vibrations of vehicles. The amplitude of vibrations is detected by the signal conditioning from the measurements with the transmission input shaft spend and the wheel speed sensors. Based upon this, a perturbation is applied additionally on the nominal launch controller to make the drive shaft oscillation vanish. It can be achieved by the control design without any extra hardware cost. Finally, experimental results confirm the effectiveness of the proposed mechanism.
2016-04-05
Technical Paper
2016-01-1616
Keiichiro Iida, Kunizo Onda, Akiyoshi Iida, Chisachi Kato, Shinobu Yoshimura, Yoshinobu Yamade, Yoshimitsu Hashizume, Yang GUO
The objective of this research is to predict accurately aeroacoustical interior noise of a car for a wide range of frequency between 100 Hz and 4 kHz. In this study, one-way coupled simulation of computational fluid dynamics (CFD), structural and acoustical analyses were performed to predict flow induced interior noise. Statistical Energy Analysis (SEA), which is a traditional method for evaluating transmission of sound and interior sound field, cannot be used for a low frequency range. In this study, structural and vibrational analysis and acoustical analysis were performed to predict the interior noise. This proposed method can be used for a wide range of frequency between 100 Hz and 4 kHz including a low frequency range. In this paper, the structural and vibrational analyses were performed by using the finite element method (FEM). The acoustical analysis results were compared the wind tunnel experimental results.
2016-04-05
Technical Paper
2016-01-0275
Frédéric Kihm, Andrew Halfpenny, Kurt Munson
Components of ground vehicles are designed to withstand the real operational conditions they will experience during their service life. Vibration tests are performed to qualify their endurance. In order to replicate the same failure mechanism as in real conditions, the test specification must be representative of the service loads. The accelerated testing method, based on fatigue damage spectra (FDS), is a process for deriving a vibration profile that has the same damage potential as the real environment. A synthesized power spectral density (PSD) is derived from the sum of all events’ FDS. So far, the obtained synthesized PSD represents a random stationary Gaussian excitation and is applied over a reduced duration. In real life, however, it is common to experience non-Gaussian excitations such as road irregularities. Random stationary Gaussian test signals do not accurately represent the bursts experienced in service use.
2016-04-05
Technical Paper
2016-01-0488
Takashi Izawa, Motohiko Koushima
The sliding bearing generally used for engine main bearing in passenger vehicles are known to show a reduction in seizure limit performance relative to ideal conditions when the bearing are subjected to the influence of various noise factor (factor exerting negative influence) under actual operating conditions. Recent passenger vehicle engine development has sought to meet the demand for higher fuel economy and specific torque by reducing the width of the bearing and increasing the input load. The environment in which bearing are used is growing ever more demanding. The influence of noise factor on seizure limit performance is believed to be on an increasing trend in conjunction with this change. The importance of ascertaining that influence is growing greater, but few attempts have been made to verify those factors quantitatively.
2016-04-05
Technical Paper
2016-01-1325
Masanori Watanabe, Yosuke Tanabe, Naoki Yoneya
Recently, the need to reduce noise generated by machines has been increasing because people are generally becoming more environmentally aware. In order to reduce noise efficiently, noise source localization technology by using microphone arrays is applied to many machines. However, it is difficult to identify noise and excitation sources of vehicle components because the size of noise and excitation source is very small compared to other machines. Therefore, the technical issue of vehicle components is to identify the excitation source finely to reduce noise effectively. Hence, the system which can identify the excitation sources has been developed by combining measurement and analysis. This enables to solve noise and vibration problems at an early stage of development and shorten the development period. Results are as follows, (1) Multi physical quantities and multi channel measurement system has been developed.
2016-04-05
Technical Paper
2016-01-1121
Fang Liao, Weimin Gao, Yan Gu, Fei Kang, Yinan Li, Cheng Wang
Noise signals of the driver’s right ear include those of engine, environment, chassis dynamometer, loaded gears and unloaded gears when they are recorded in full vehicle on chassis dynamometer in semi-anechoic room. Gear rattle noise signals of the driver’s right ear caused by unloaded gear pairs can’t be identified or quantified directly. To solve the problems, relative approaches are used to identify and quantify the gear rattle noise signals. Firstly, the rattle noise signals of the driver’s right ear are filtered by human ear characteristic functions and steady noise signals are extracted by regression and smoothing processes. The noise signals are regressed at 200ms interval in the hearing critical frequency bands and smoothed in the flanking frequencies. Then, the noise relative approaches are obtained by subtracting the steady noise signals from the filtered noise signals, which are the transient noise signals of the unloaded gear pairs inducing the rattle noise.
2016-04-05
Technical Paper
2016-01-1309
Yingping Lv, Yongchang Du, Yujian Wang
In this paper, analysis methods for brake squeal including substructure modal composition analysis and substructure modal parameters sensitivity analysis are presented. The methods are based on a new closed-loop coupling disc break model, where the coupled nodal pairs in each coupling interface are connected tightly. This assumption is different from other existing models in literatures, where the interface nodes are coupled through assumed springs. Based on this new model, two analysis methods are derived. Substructure modal composition analysis indicates the contribution of modes of each substructure to the noise mode. Substructure modal parameters sensitivity analysis calculates the sensitivity of each component’s modal frequencies and shape coefficients to the real part of eigenvalues. Finally, the presented analysis methods are applied to analysis a high frequency squeal problem of a squealing disc brake.
2016-04-05
Technical Paper
2016-01-1094
Fang Liao, Weimin Gao, Yan Gu, Fei Kang, Yinan Li, Cheng Wang
Generally, the gear rattle noise prediction models are composed of the mass and stiffness elements. The proposals are about the gear inertia or backlash and the shaft inertia, stiffness, but there are many detailed designs in the same inertia, stiffness or backlash conditions. Therefore, these proposals cannot guide detailed designs. These models only investigate the rattle in the rotating degree, and ignore rattle contribution in the radical and axial directions. Those prediction models only consider one or several factors which affect the rattle noise performance. It is difficult to predict the influence of individual factor and multi-factors coupling on the gear rattle noise in a rattle simulation model.
2016-04-05
Technical Paper
2016-01-1557
Francesco Castellani, Nicola Bartolini, Lorenzo Scappaticci, Davide Astolfi, Matteo Becchetti
Shock absorber is one of the most relevant sub-systems of the suspension system for a wide range of vehicles. Although a high level of development and tuning has been reached, in order to ensure high safety standards in almost every situation, some dynamic phenomena affecting vehicle handling or NHV can appear. The aim of present work is to improve a mathematical model using experimental data from a prototype of monotube shock absorber developed for research purposes. The model takes into account all the main features affecting the global performance of the device, such as non-linear behaviour and the presence of hysteresis loops. Actually, the most important parameters are analyzed, as flow and orifice coefficients of the valves, coefficients of mechanical compliance of the chambers and oil compressibility, dry and viscous friction coefficients.
2016-04-05
Technical Paper
2016-01-1040
Rostislav Hadas, Rolf Sauerstein, Radúz Zahoranský, Michael Stilgenbauer, Matthias Ruh
A new generation of gasoline engine Turbochargers has been developed with a focus on high performance and excellent NVH characteristics, especially with regards to the Wastegate control system. With the recent introduction of EU6 emission standards there is a clear demand to precisely control the flow of exhaust gas through a Turbocharger Wastegate. Engine operational duty cycles measured on EU6 compatible vehicles have shown an increased stress on wastegate parts due to a higher amount of regulation strokes during operation. Recent developments in the compact design of exhaust systems together with high pressure pulsation forces acting on wastegate flaps constitute the main challenges facing turbo engineers in the effort to achieve customer durability and meet NVH requirements. For the development of a new generation of wastegate control systems a unique load prediction model was duly developed.
2016-04-05
Technical Paper
2016-01-1294
Jonggyu KIM, Pyoung Beom Kim, YoungChan Lee, Sunghee Jung, Byeong-Ug Choi
This paper presents the characteristics of a 3 Cylinder CVT vehicle and a process to improve fuel economy and reduce noise and vibration. To increase the lock-up area of damper clutch for the high fuel economy and to decrease booming and vibration affected by lock-up, chassis systems of a driveline and structure resonance characteristics are studied by experiment and simulation. CVT software calibration parameters are optimized for fuel economy and NVH. With This Study, the lock-up area has been increased by 300RPM and the fuel economy has been improved by approximately 1%, while the NVH characteristic is almost same.
2016-04-05
Technical Paper
2016-01-0473
Muthukumar Arunachalam, Arunkumar S, PraveenKumar Sampath, Abdul Haiyum, Beverly Katz
Current generation passenger vehicles are built with several electronic sensors and modules which are required for functioning of passive safety systems precisely and thus directly related to overall vehicle level performance. Most of these sensors and modules are needed to be mounted on vehicle body at locations like pillar or even directly on panels based on its safety functionality and packaging requirements. The body panel or pillar poses local structural resonances and its dynamic behavior might directly affect the functioning of these sensors and modules. Hence the sufficient inertance performance level at sensor mounting locations is required for the proper functioning of those sensors and modules to meet the vibrational target requirement. Drive point modal frequency response function (FRF) analysis at full vehicle model for the frequency range up to 1000 Hz is performed using finite element method (FEM) and verified against the target level.
2016-04-05
Technical Paper
2016-01-1349
Siddharth Bhupendra Unadkat, Suhas Kangde, Mahalingesh Burkul, Mahesh Badireddy
In current scenario, tremendous amount of thrust is there on CAE to simulate the customer usage pattern or lab test using virtual simulation methods. And is of prime importance to reduce the number of soft tooled or hard tooled prototype for a test if it can be well predicted in CAE. Door slam event in automobiles is one, where structure’s behaviour is complex due to vibration of panels. Current work focuses to derive load histories at different mounting points like hinges, latch and contact patch of door seal area through dynamic analysis using LSDyna. The extracted load histories are then applied to trimmed door Nastran model and Modal transient analysis performed to find the stress history. There is computational advantage with Nastran for performing multiple design iterations compared to LSDyna. Also, stress convergence is achieved with Nastran model. The stresses shown higher in the region where actual failure happened.
2016-04-05
Technical Paper
2016-01-1321
Masahiro Fukazawa, Tsuyoshi Murao, Shingo Unigame
The CAE method to predict the vibration transfer function of the fluid engine mount on a vehicle with sufficient precision and calculation time without prototype cars was developed. The transfer function is given in the following steps.First, rubber deformation form under the power train weight loaded must be predicted. It’s obtained by using a reduction model of engine mount, as a unit, which doesn’t have its fluid sealed inside, with the technique to get static spring characteristics in a non-linear relationship. Second, Young’s modulus and structural damping coefficient for the deformed rubber must be given. As for these characteristics, ignoring the relations between these values and strain, the constant values are used. This considerably reduced computation time and model size.Next, the reduction model and the fluid model which actually the engine mount has must be combined to express actual product.
2016-04-05
Technical Paper
2016-01-1549
Nicola Bartolini, Lorenzo Scappaticci, Francesco Castellani, Alberto Garinei
The knocking noise is a transient structural noise triggered by the shock absorber's piston rod vibrations that excites the vibration of chassis components. Piston rod vibrations can be caused by valves motion (opening and closing) and dry friction during stroke inversions. This study investigates the shock absorber knocking noise on a twintube gas-filled automotive shock absorber and the aim is to define an acceptance criterion (threshold level) for a sample check of the component. If infact the damper derives from a large mass production, may happen that small differences in the assembly might lead to different behaviours resulting in higher or lower levels of knocking noise. To achieve the goal, experimental tests were carried out at various excitation frequencies and amplitudes. Test were performed using a oleodynamic test bench monitoring displacement and force; accelerometers were placed in proximity of the rebound valve, on the body of the damper and on the piston rod.
2016-04-05
Technical Paper
2016-01-1069
Masayoshi Otaka, Taro Kasahara, Kenichi Komaba
As a means of further improving combustion efficiency of gasoline engine, an increase in compression ratio, which enhances the risk of knocking, is thinkable. To optimize engine combustion parameters, a technology that can precisely detect knocking is desirable. Presently skillful experts have been evaluating knocking subjectively by listening to radiation noise so far. The authors developed a device that can precisely detect knocking by means of processing sound signals, which are captured by a high-performance microphone that is sensitive in the wide frequency range. Shock waves induced by knocking cause in-cylinder gas vibrations that emits metallic hit noises from the outer engine wall. We studied how to identify the feature values of frequency characteristics when knocking occurs, under the assumption that the engine radiation noise includes more than 2nd-order harmonic components with respect to the basic frequency of the in-cylinder gas vibration mode.
2016-04-05
Technical Paper
2016-01-0479
Kuniaki Goto, Takashi kondo, Masakiyo Takahira, Eiji Umemura, Masashi Komada, Yasuhiko Nishimura
Generally, the field pass-by noise level measurement is not stable under the influence of weather conditions , background noise and driver’s skill.So, automobile manufactures try to reproduce proving ground driving on chassis dynamometer measurement.But, the tire noise on actual road surface is difficult to replace on indoor test. In 2016,new pass-by noise regulation (UN R51-03)will take effect in Europe and Japan etc. Furthermore , 2dB stricter regulation will take effect in 2020. In addition to the acceleration run of the current regulation , UN R51-03 requests constant speed run . Therefore, the efficient measurement is necessary for vehicle development. To solve the above mentioned issues , we have developed an indoor evaluation system capable of reproducing the tire noise on road surface.
2016-04-05
Technical Paper
2016-01-1361
Abhijit Londhe, Vivek Yadav, SenthilKumar Kannaiyan, Krishnan Karthikeyan, Ganeshan Reddy
Reducing the vibrations in the drivetrain is one of the prime necessities in today’s automobiles from NVH and strength perspectives. Also to save on material costs and to improve on fuel economy there is a need for optimizing the mass of the engine and vehicle. Platform strategy enables several variants to be designed by changing parameters like Powertrain, wheel base, payload. In those scenarios, changes in stiffness, operating speeds can impact dynamics of drivetrain and of vehicle, this leads to a greater need for addressing the NVH, durability and overall vehicle performance through simulation. Other challenges design engineers have to face are reducing vibrations transferred to vehicle through different load paths such as directly through body mounts and through axle to suspension and then to vehicle cabin. This aggravates other concerns such as shift lever vibrations, rise in in-cab noise, and generation of boom noise at certain speeds.
2016-04-05
Technical Paper
2016-01-0273
Richard DeJong, Se Ge Jung, John Van Baren
Methods for conducting accelerated vibration fatigue testing of structures, such as MIL-STD-810G, allow for the non-linear scaling of the test time with the inverse of the rms vibration amplitude based on the slope of the material S-N curve obtained from cyclic fatigue tests. The Fatigue Damage Spectrum (FDS) is used as a method to allow for different level scalings at different frequencies in a broadband vibration environment using the relative responses of resonances in the structure. A recent development in industry has been to mix impulses with random excitations to increase the vibration peak levels (as measured by the kurtosis), thereby accelerating the fatigue even more than would occur with a Gaussian excitation. This paper presents results from a study to determine the conditions under which high kurtosis, impulsive excitations actually produce high kurtosis responses in structural resonances thus increasing the level of the FDS.
2016-04-05
Technical Paper
2016-01-1300
Jacob Milhorn, Vincent Rovedatti, Richard DeJong, Gordon Ebbitt
Road tests on a pickup truck have been conducted to determine the acoustic loads on the back panel surfaces of the vehicle. Surface mounted pressure transducers arrays are used to measure both the turbulent flow pressures and the acoustic pressures. These measurements are used to determine the spatial excitation parameters used in an SEA model of the transmission loss through the back panel surfaces. Comparisons are made between tests on different road surfaces and at different speeds to identify the relative contributions of tire and wind noise. Comparisons are also made with wind noise measurements in a scale model wind tunnel test.
2016-04-05
Technical Paper
2016-01-0055
Mark Steffka, Cyrous Rostamzadeh
Automotive systems can generate un-intentional radio frequency energy. The levels of these emissions must be below maximum values set by the Original Equipment Manufacturer (OEM) for customer satisfaction and/or in order to meet governmental requirements. Due to the complexity of electromagnetic coupling mechanisms that can occur on a vehicle, many times it is difficult to measure and identify the noise source(s) without the use of an electromagnetic interference (EMI) receiver or spectrum analyzer (SA). An efficient and effective diagnostic solution can be to use a low-cost portable, battery powered RF detector with wide dynamic range as an alternative for automotive electromagnetic compatibility (EMC) and design engineers to identify, locate, and resolve radio frequency (RF) noise problems. A practical circuit described here can be implemented easily with little RF design knowledge, or experience.
2016-04-05
Technical Paper
2016-01-0475
Lingzhi Li, Jun Li, Bingwu Lu, Yingjie liu, Zhi Zhang, Hailong Cheng, Yan Zhang, Hangsheng Hou
Excessive wind noise is one of the most complained problems by owners of new vehicles as evidenced by the 2013 JD Power IQS (Initial Quality Study). After the vehicle speed surpasses 60 mph, wind noise is gradually becoming the dominant noise source. In an effort to reduce aeroacoustic noise level, Beamforming is a very effective noise source identification technique used during vehicle wind noise development phases. Based on the delay-and-sum (DAS) planar Beamforming methodology, a large semi-circle acoustic array is designed according to the required resolution and dynamic range pertaining to actual noise source distribution on a typical passenger vehicle. Acoustic array calibration and photo overlay are accomplished by multi-point source method, and the Doppler Effect due to the wind is corrected by the location calibration method. The established system is applied to identifying the exterior noise sources on driver-side of a passenger vehicle in the wind tunnel.
2016-04-05
Technical Paper
2016-01-1301
Shishuo Sun, David W. Herrin, John Baker
One of the more useful metrics to characterize an isolator is insertion loss. Insertion loss is defined as the difference in transmitted vibration in decibels between the unisolated and isolated cases. Insertion loss is superior to transmissibility in that effects of source and receiver compliance are also included. In this work, the transfer matrix of a spring isolator is determined using finite element simulation and the insertion loss is then determined using assumed values for the compliance on the source and receiver sides. Following this, the effect of different spring parameters such as the number of turns, wire diameter, spring diameter, and damping are investigated.
2016-04-05
Technical Paper
2016-01-1061
Guiping Yue, Wenbo Niu, Jian Zhao, Dandan Kong, Yun Li, Hangsheng Hou
Gear whine noise impacts customer perception of the interior sound quality, and it has been a much discussed topic regarding the transmission NVH performance in the automotive industry. Based on multi-body dynamics, this work carries out a transmission system whine noise simulation, taking into consideration of gear macro parameter setting and micro tooth surface modification theory. Along the same line, the transmission gear macroscopic and microscopic parameters are optimized. The results show that the control of gear transmission error is an effective measure to resolve the transmission noise issue.
2016-04-05
Technical Paper
2016-01-1322
Tonghang Zhao, Xining Liu, Yuntao Cao, Chao Li, Hangsheng Hou
When battery power becomes insufficient, Hybrid cars will start the engine which drives the motor to charge the battery to realize the function of the electric drive. One important situation is the activation of the charging mode during idle, which could lead to serious NVH problems. This work proposes a noise control method during battery charging under idle condition for hybrid electric vehicles by studying the powertrain modal alignment, idle condition optimization, electric motor control mechanism based on the automotive vibration and noise control theory and the structure characteristics of hybrid electric vehicles. Finally, a real development case is provided regarding the resolution of a noise issue due to idle charging for a hybrid vehicle program.
2016-04-05
Technical Paper
2016-01-1060
Arnab Ganguly, Niket Bhatia, Vikas Kumar Agarwal, Ulhas Mohite
With ride comfort in a motorcycle gaining significance, it is important to minimize vibration levels at the customer touch points. The reciprocating piston imparts rotary motion to the crankshaft which in turn induce unbalance forces and produces vibration in the vehicle, thus influencing the ride quality. Generally, the primary inertial forces are balanced by a combination of balancer body and crank web. However, being a commuter bike, a balancer body could not be accommodated due to cost and space constraints. In such scenario, the primary unbalance forces cannot be completely eliminated but can only be redistributed by adding counterweight to the crankshaft. Proper distribution of these forces are required for optimum vibration levels at motorcycle touch sensitive points (TSP) such as handle bar, footrest etc.
2016-04-05
Technical Paper
2016-01-1053
Vigneshwara raja kesavan
Scooters have been playing an important role in personal transportation over the last few decades in developing countries. Achieving Noise, Vibration and Harshness (NVH) targets in small two-wheeler scooter engines are challenging due to ever-increasing customer expectations and stringent regulatory norms. Considering the vehicle layout of scooters, reducing noise from cylinder head and valve train becomes critical in achieving the overall noise targets. This paper discusses various noise sources of cylinder head assembly and focuses on various design options developed to reduce the cylinder head noise in a single cylinder, 110cc scooter engine. Various experimental procedures were used for identification and ranking of different noise sources and transfer path. In case of air-cooled small engines, temperature effects are dominant and as a consequence certain noises stand out in hot condition causing severe noise discomfort.
2016-04-05
Technical Paper
2016-01-0220
Ban Gu, Xiaohong Yuan
With great development of thermoelectric exhaust heat recovery technology, more and more attention has been paid to optimization of automotive thermoelectric generators (ATEGs). A lot of work has been done on optimization of flow field and thermal analysis, however work that focuses on acoustic optimization is not too much. In this paper, efforts have been paid to research acoustic performance of a flat-plate TEG, and to check out the feasibility of integration of automotive exhaust thermoelectric generator with muffler. The internal configuration of heat exchanger looks like “fishbone”. Four factors have been taken into consideration: the spacing of two fins, angle of the fins, the diameter of inlet and outlet of exchanger, and filling sound absorbing material in heat exchanger chamber. Based on these four factors, acoustic analysis was carried out.
Viewing 31 to 60 of 9221

Filter

Subtopics