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Viewing 241 to 270 of 8671
2014-04-01
Technical Paper
2014-01-1686
Pablo Ballesteros, Xinyu Shu, Christian Bohn
In this paper, a control approach for the active reduction of engine-induced vibrations in automotive vehicles is presented. As a controller, a discrete-time multiple input multiple output (MIMO) disturbance-observer-based state-feedback controller is designed using linear parameter-varying (LPV) gain-scheduling techniques. The use of LPV control design techniques has the advantage that the stability of the overall system is guaranteed even when the gain-scheduling parameters are changing. The control approach is validated experimentally with an active vibration control system installed in a Golf VI Variant. Two inertia-mass actuators (shakers) and two accelerometers are attached to the engine mounts. Nine frequency components are targeted in the reduction and excellent results are achieved in vehicle driving tests for constant and time-varying engine speeds.
2014-04-01
Technical Paper
2014-01-1682
Zhengfei Tang, Yongfu Chen, Jian Zeng, Yu Yang, Yunqing Zhang
NVH quality is one of the most important criteria by which people judge the design of a vehicle. The Powertrain Mounting System (PMS), which can reduce the vibration from engine to vehicle cab as well as the inside noise, has attained significant attention. Much research has been done on the isolation method for three- and four-point mounting. But the six-point mounting system, which is usually equipped in commercial vehicle, is seldom studied and should be paid more attention. In this paper, the support rod installed on the upside of the transmission case is considered as a flexible body. Thus a rigid-flexible coupling model of PMS is established and the necessity of the established model is analyzed by comparing the simulation results of the new model and those of the conventional model. Based on the traditional theory of energy decoupling and reasonable allocation of the natural frequencies, Adams and MATLAB are integrated into the optimization software iSIGHT to optimize the six-point PMS.
2014-04-01
Technical Paper
2014-01-0017
Masashi Terada, Takashi Kondo, Yukihiro Kunitake, Kunitomo Miyahara
Abstract In automobile development, steering vibrations caused by engine excitation force and suspension vibration input from the road surface are a problem. The conventional method of reducing vibrations and thereby securing marketability has been to dispose a dynamic damper inside the steering wheel. The resonance frequency of a steering system varies for each vehicle developed (as a result of the vehicle size, the arrangement of the stiff members of the vehicle body, and the like). As a result, the individual values of dynamic dampers that are used with vehicles must be adjusted for each developed vehicle type. To address this problem, we have developed a new structure in which, rather than using a conventional dynamic damper, we disposed a floating bush on the Supplemental Restraint System (SRS) module attachment section and used the SRS module itself as the weight for the dynamic damper. In this structure, the dynamic damper weight is approximately eight times greater than the conventional weight, the vibration reduction effect is enhanced, and the effective frequency range is widened.
2014-04-01
Technical Paper
2014-01-0887
Weiguo Zhang, Rakesh Khurana, Mark Likich, Mac Lynch
Taguchi method is a technology to prevent quality problems at early stages of product development and product design. Parameter design method is an important part in Taguchi method which selects the best control factor level combination for the optimization of the robustness of product function against noise factors. The air induction system (AIS) provides clean air to the engine for combustion. The noise radiated from the inlet of the AIS can be of significant importance in reducing vehicle interior noise and tuning the interior sound quality. The porous duct has been introduced into the AIS to reduce the snorkel noise. It helps with both the system layout and isolation by reducing transmitted vibration. A CAE simulation procedure has been developed and validated to predict the snorkel noise of the porous ducted AIS. In this paper, Taguchi's parameter design method was utilized to optimize a porous duct design in an AIS to achieve the best snorkel noise performance. The virtual experiments based on an orthogonal array in the parameter design method were conducted by the developed simulation procedure and the optimized design was recommended.
2014-04-01
Technical Paper
2014-01-0889
Shuming Chen, Yawei Huang, Dengfeng Wang, Dengzhi Peng, Xuewei Song
This paper proposes a new method of predicting the sound absorption performance of polymer wool using artificial neural networks (ANN) model. Some important parameters of the proposed model have been adjusted to best fit the non-linear relationship between the input data and output data. What's more, the commonly used multiple non-linear regression model is built to compare with ANN model in this study. Measurements of the sound absorption coefficient of polymer wool based on transfer function method are also performed to determine the sound absorption performance according to GB/T18696. 2-2002 and ISO10534- 2: 1998 (E) standards. It is founded that predictions of the new model are in good agreement with the experiment results.
2014-04-01
Technical Paper
2014-01-0933
Mohamed Senousy, Paul Larsen, Peiran Ding
Electric motors and generators produce vibrations and noise associated with many physical mechanisms. In this study, we look at the vibrations and noise produced by the transient electromagnetic forces on the stator of a permanent magnet motor. In the first stage, electromagnetic simulation is carried out to calculate the forces per tooth segment of the stator. The harmonic orders of the electromagnetic forces are then calculated using Fourier analysis, and forces are mapped to the mechanical harmonic analysis of the second stage. As a third stage, the vibrations of the structure are used to drive the boundary of acoustic domain to predict the noise. Finally, optimization studies are made over the complete system to improve the motor design and reduce noise. A simulation environment (ANSYS Workbench) is used to integrate a seamless workflow.
2014-04-01
Technical Paper
2014-01-1938
Pragadish Nandakumar
The fuel prices are increasing every day and so are the pollution caused by vehicles using fossil fuels. Moreover, in a car with an internal combustion engine, we get on average 25% efficiency, the other 75% is wasted, mostly through friction and heat. One important loss is the dissipation of vibration energy by shock absorbers in the vehicle suspension under the excitation of road irregularity and vehicle acceleration or deceleration. In this paper we design, manufacture and test a regenerative coil-over strut that is compact, simple in design and more economical. Since our strut is a modification of an existing strut design, it would be much more feasible to implement. We tested our prototype strut using a TATA Indica car under city road conditions. The damping characteristics and output voltage of the strut were recorded and compared with a normal coil over strut. Based on the test data, it was found that the strut was able to recover about 8-10 watts of electricity at 20kmph.
2014-04-01
Technical Paper
2014-01-1981
Devadatta Mukutmoni, Robert Powell, L.A.Raghu Mutnuri
Flow generated acoustic sources are of significant import for automotive applications since perception of noise is a critical customer satisfaction issue. High temperature acoustic sources known as thermo-acoustics such as those occurring inside an exhaust system of a vehicle, an important subset of acoustic sources, is the subject of the investigation. In this article, we study a Rijke tube configuration that consists of a vertical and hollow cylindrical tube open at both ends where sound is generated by buoyancy driven flow as a result of a heated wire gauze placed in the bottom half of the tube. This configuration captures the essence of the thermo-acoustic phenomena and was investigated both numerically and experimentally and good agreement was observed between the two.
2014-04-01
Technical Paper
2014-01-1976
Shuming Chen, Dengfeng Wang
In this paper, the relationship was investigated between objective psychoacoustic parameters, A-weighted sound pressure level (SPL) and the results of the subjective evaluation by using grey relational analysis (GRA). The sounds were recorded with eight different passenger cars at four different running conditions. The sound quality indices were calculated, including loudness, sharpness, roughness, fluctuation, and A-weighted SPL. Subjective evaluation was performed by thirty subjects using rating scale method. GRA was compared with traditional correlation analysis, and the comparison shows that some hidden information which could not be found in the traditional correlation analysis was revealed. In order to know the further relationship between fluctuation and subjective evaluation, another subjective evaluation was performed by the same 30 subjects. The result demonstrates that the relationship revealed from GRA is correct. Furthermore, some measures were presented to improve the sound quality of vehicle interior noise.
2014-04-01
Technical Paper
2014-01-0008
Wei Yang, Wenku Shi, Chunxue Chen
Aiming at the abnormal vibration of driver seat of a passenger car in idle condition, vibration acceleration of engine, frame and seat rail was tested to identify vibration sources. Order tracking and spectrogram analysis indicated that the second order self-excitation of engine was the main cause. To solve the problem, semi-active controlled hydraulic engine mount with air spring of which characteristics could shift between a high dynamic stiffness and a low one was applied. Then the structure and principle of the mount with variable characteristics was introduced and control mode was analyzed. Dynamic characteristics were obtained by bench test. With sample mount applied, vibration of seat rail was tested again in multiple vehicle and engine working conditions. Dates showed that abnormal vibration in idle condition was extremely reduced and the mount could also meet the requirement of engine to dynamic stiffness in driving conditions.
2014-04-01
Technical Paper
2014-01-0006
Tamer Elnady, Mats Abom, Yong Yang
Exhaust noise is a major contributor to the radiated noise level of a vehicle, especially at idle. The radiated noise level has to meet a certain criteria based on regulation and consumer demand. In many cases, the problem appears after the vehicle is manufactured and the tailpipe noise measurement is performed indicating a high noise level that needs to be reduced. This paper describes one of those cases where the radiated noise level of a certain passenger car at idle was required to be reduced by 6 dB(A). The exhaust system consists of one main muffler and one auxiliary muffler. A 1D two-port model of the exhaust system including the two mufflers was built using commercial software. This model was validated against the measurement of the two-port matrix of both mufflers. The model was then used together with tailpipe noise measurements to estimate the characteristics of the source strength and impedance. Using a 1D model of the complete system, it was possible to propose several modifications for the vehicle manufacturer to choose from.
2014-04-01
Technical Paper
2014-01-0021
Meng Huang
A 2 DOF nonlinear dynamic model of the automotive wiper system is established. Complex eigenvalues are calculated based on the complex modal theory, and the system stability as well as its dependence on wiping velocity is analyzed. Bifurcation characteristics of frictional self-excited vibration and stick-slip vibration relative to wiping velocity are studied through numerical analysis. Research of nonlinear vibration characteristics under various wiping velocities is conducted by means of phase trajectories, Poincaré map and frequency spectrum. The pervasive stick-slip vibration during wiping is confirmed, and its temporal and spatial distributions are analyzed by way of time history and contour map. Duty ratio of stick vibration and statistics of scraping residual are introduced as quantitative indexes for wiping effect evaluation. Results indicate that the negative slop of frictional-velocity characteristic is the root cause of system instability. As the wiping velocity decreases, the vibration state transforms from periodic to quasi-periodic and then to chaos in both high and low velocity ranges.
2014-04-01
Technical Paper
2014-01-0023
Cha-Sub Lim, Eunjun Han, Chahe Apelian, David Bogema
A new approach to achieve better customer perception of overall vehicle quietness is the sound balance improvement of vehicle interior sound during driving. Interior sound is classified into 3 primary sound source shares such as engine sound relative to revolution speed, tire road noise and wind noise relative to vehicle speed. Each interior sound shares are classified using the synchronous time-domain averaging method. The sound related to revolution order of engine and auxiliaries is considered as engine sound share, tire road noise and wind noise shares are extracted by multiple coherent output power analysis. Sound balance analysis focuses on improving the relative difference in interior sound share level between the 3 primary sound sources. Virtual sound simulator which is able to represent various driving conditions and able to adjust imaginary sound share is built for several vehicles in same compact segment. Objective sound evaluation targeting the North American customer is carried out using the virtual sound simulator tool in audio lab and it is verified that overall customer perception is improved by modification of sound balance between 3 primary sound shares.
2014-04-01
Technical Paper
2014-01-0027
Meng Huang
A disc-pad system is established to study impacts of surface topography on brake squeal from the perspective of statistical analysis. Firstly, surface topographies of brake disc and pad are precisely measured on the scale of micron and are statistically analyzed with a three-dimensional evaluation system. Secondly, the finite element model of brake disc and pad without surface topographies is created and verified through component free modal tests. Thereby the valid brake squeal model for complex modal analysis is built with ABAQUS. An effective method is developed to apply interface topographies to the smooth contact model, which consequently establishes sixty brake squeal models with topographies. Thirdly, impacts of surface topography on brake squeal are studied through comparison and statistical analysis of prediction results with and without topographies. The analysis manifest that topography amplitudes and evaluation index deviations of brake pad far exceed those of the disc, indicating the surface of brake pad is relatively much rougher.
2014-04-01
Technical Paper
2014-01-0591
Nicholas Oettle, David Sims-Williams, Robert Dominy
On-road, a vehicle experiences unsteady flow conditions due to turbulence in the natural wind, moving through the unsteady wakes of other road vehicles and travelling through the stationary wakes generated by roadside obstacles. Separated flow structures in the sideglass region of a vehicle are particularly sensitive to unsteadiness in the onset flow. These regions are also areas where strong aeroacoustic effects can exist, in a region close to the passengers of a vehicle. The resulting aeroacoustic response to unsteadiness can lead to fluctuations and modulation at frequencies that a passenger is particularly sensitive towards. Results presented by this paper combine on-road measurement campaigns using instrumented vehicles in a range of different wind environments and aeroacoustic wind tunnel tests. A new cabin noise simulation technique was developed to predict the time-varying wind noise in a vehicle using the cabin noise measured in the steady environment of the wind tunnel, and a record of the unsteady onset conditions on the road, considering each third-octave band individually.
2014-04-01
Technical Paper
2014-01-0869
Guangqiang Wu, Shuyi Jin
During a car launch, the driving torque from driveline acts on brake disk, and may lead the pad to slip against the disk. Especially with slow brake pedal release, there is still brake torque applies on the disk, which will retard the rotation of disk, and under certain conditions, the disk and pad may stick again, so the reciprocated stick and slip can induce the noise and vibration, which can be transmitted to a passenger by both tactile and aural paths, this phenomenon is defined as brake groan. In this paper, we propose a nonlinear dynamics model of brake for bidirectional, and with 7 Degrees of Freedom (DOFs), and phase locus and Lyapunov Second Method are utilized to study the mechanism of groan. Time-frequency analysis method then is adopted to analyze the simulation results, meanwhile a test car is operated under corresponding conditions, and the test signals are sampled and then processed to acquire the features. Finally, the results of the simulation and those of the test are compared, and the mechanism of groan and its contributory factors are revealed.
2014-04-01
Technical Paper
2014-01-0888
V. Jadon, G. Agawane, A. Baghel, Venkatesham Balide, R. Banerjee, A. Getta, H. Viswanathan, A. Awasthi
Abstract With significant decrease in the background noise in present day automobiles, liquid slosh noise from an automotive fuel tank is considered as a major irritant during acceleration and deceleration. All major international OEMs and their suppliers try to reduce sloshing noise by various design modifications in the fuel tank. However, most major activities reported in open literature are primarily based on performing various CAE and experimental studies in isolation. However, noise generation and its propagation is a multiphysics phenomenon, where fluid mechanics due to liquid sloshing affects structural behaviour of the fuel tank and its mountings which in turn affects noise generation and propagation. In the present study a multiphysics approach to noise generation has been used to predict liquid sloshing noise from a rectangular tank. Computational Fluid dynamics (CFD), Finite Element Analysis (FEA) and Boundary Element Method (BEM) simulation studies have been performed in a semi-coupled manner to predict noise.
2014-04-01
Technical Paper
2014-01-1272
Jeremie Dernotte, John E. Dec, Chunsheng Ji
This article presents an investigation of the sources combustion-generated noise and its measurement in HCCI engines. Two cylinder-pressure derived parameters, the Combustion Noise Level (CNL) and the Ringing Intensity (RI), that are commonly used to establish limits of acceptable operation are compared along with spectral analyses of the pressure traces. This study focuses on explaining the differences between these two parameters and on investigating the sensitivity of the CNL to the ringing/knock phenomenon, to which the human ear is quite sensitive. Then, the effects of independently varying engine operating conditions such as fueling rate, boost pressure, and speed on both the CNL and RI are studied. Results show that the CNL is not significantly affected by the high-frequency components related to the ringing/knock phenomenon. In contrast, CNL is found to be sensitive to increasing energy in the 0.4 to 2.0 kHz frequency range generated by the combustion-induced uniform pressure rise.
2014-04-01
Technical Paper
2014-01-1678
Kenji Torii
A technique was created to separate the contributions of combustion noise and mechanical noise to engine noise in the time domain in order to achieve efficient measures for enhancing the sound quality of combustion noise. There is an existing technique based on 1/3 octave band analysis that is known as a method for separating the contributions to engine radiation noise, but this technique cannot provide time-domain data. Therefore, the author has proposed a technique that separates engine radiation noise into combustion noise and mechanical noise in the time domain by finding the combustion noise for each cylinder and calculating its structural response function by considering its real and imaginary components. Results of analysis of actual engine radiation noise with this technique confirmed that combustion noise, which is characterized by strong pulsation, and irregular mechanical noise can be separated in the time domain with good precision. Moreover, the structural response function, combustion noise, and mechanical noise characteristics showed a valid changing trend in response to changes in cylinder pressure and structural specifications.
2014-04-01
Technical Paper
2014-01-1675
Joe Serrano, Geoff Routledge, Norman Lo, Mark Shost, Vijay Srinivasan, Biswa Ghosh
Cylinder deactivation is a technology seeing increased automotive deployment in light of more demanding fuel economy and emissions requirements. Examples of current production systems include GM's Active Fuel Management and Chrysler's Multi-Displacement System, both of which provide one fixed level of deactivation. Dynamic Skip Fire (DSF), in which the number of fired cylinders is continuously varied to match the torque demand, offers significantly increased fuel savings over a wider operating range than the current production systems. One of the biggest challenges in implementing cylinder deactivation is developing strategies to provide acceptable Noise, Vibration and Harshness (NVH); this paper discusses those challenges and the methodologies developed. This work covers theoretical root causes; proposed metrics to quantify the NVH level; algorithmic and physical mitigation methods; and both subjective and objective evaluation results.
2014-04-01
Technical Paper
2014-01-1683
Hiroki Yamaura, Masao Ishihama, Kazuhide Togai
Engine torque profile shaping strategies have been proposed to reduce noise & vibration for passenger cars. However, it has not been sufficiently studied that feasible torque profile for vibration suppression is dependent on engine speed and target torque shape. On the other hand, combustion pressure profile shaping strategies have been proposed to reduce noise. However, there is almost no research of the quantitative evaluation of contribution of combustion pressure profile. First, the torque profile shaping was studied. Pre-compensated torque and 2-step torque were selected as typical target torque profiles. An effectiveness of vibration suppression by two torque profiles was evaluated by both drivetrain vibration model and engine torque profile model which have been established well. As a result of studying the torque profile shaping, timing of torque rise by the 2-step torque generation is delayed or advanced. Torque profile by the pre-compensation is deformed in steep change part.
2014-03-25
WIP Standard
J1477
This SAE Recommended Practice establishes the test procedure, environment, instrumentation, and data analyses for comparing interior sound level of passenger cars, multipurpose vehicles, and light trucks having gross vehicle weight rating (GVWR) of 4540 kg (10 000 lb) or less. The test procedure is characterized by having fixed initial conditions (specified initial vehicle speed and gear selection at the starting point on the test site) to obtain vehicle interior sound measurement during road load operation over various road surfaces at specified constant speeds. The measurement data so derived is useful for vehicle engineering development and analysis.
2014-03-24
Article
Massachusetts will be the home, and MIT the beneficiary, of a new FAA-designated unmanned aircraft test site just an hour and a half from campus. MIT classes and researchers developing unmanned aerial vehicles and their associated systems will be able to take advantage of the facility located at Joint Base Cape Cod, according to MIT Professor Jonathan How of the Department of Aeronautics and Astronautics.
2014-03-24
Technical Paper
2014-01-2015
Ulhas Mohite, Prashant Bhavsar
Abstract In this paper the approach to predict vibrations in motorcycles is presented. It can be divided mainly in two parts: prediction of engine forces using multi body dynamics (MBD) simulation and prediction of vibration response using FEA. Dynamic forces predicted at each engine mount through MBD simulation are used as input to FE analysis for vibration prediction. Single cylinder SI engine having primary balancer shaft is considered to develop this methodology. Flexibilities of important parts are considered for MBD simulation. Crankshaft ball bearing which is used in almost all two wheeler engine is modeled with 6×6 stiffness matrix. It provides coupling between radial, axial and tilting deflections of bearing and it also allows moment transfer from crankshaft to casing. This helps to predict realistic forces at each bearing and engine mounts. Distribution of primary and secondary forces at crank bearings and at different engine mounts is studied. Forces predicted from MBD simulation at each engine mounts are applied to full vehicle FE model.
2014-03-12
Article
DGE Inc.'s HMIts, which simulates a user’s speech and touch and then validates the response of the infotainment system, enables OEMs and Tier suppliers to perform repetitive testing on any HMI/infotainment system in a controlled environment, ensuring accurate results and eliminating the need for time-consuming and labor-intensive manual test plans.
2014-03-12
Article
dSPACE’s latest solution for electric motor testing combines SCALEXIO hardware-in-the-loop (HIL) simulation technology with an DS2655 FPGA base module and a scalable electronic load to enable users to test electric motor control systems in a more realistic environment by emulating the real motor and generator currents.
2014-03-11
Article
The Miniscan IRXpert analyzer from AMETEK Petrolab Co. is a portable multi-fuel analyzer for gasoline, diesel, and biodiesel blends incorporating mid-IR and near-IR spectroscopy to achieve accuracy of fuel properties. It will be displayed a the SAE 2014 World Congress in Detroit April 8-10.
2014-03-10
Article
Billing itself as the "first-ever open-source race team," Perrinn myTeam is inviting students, professional engineers, and others to contribute and share data for development of a possible sports car entry at Le Mans in 2015.
2014-03-10
Article
Engineers at NASCAR's Research & Development Center in Concord, NC, recently performed three separate window net and window net mounting tests and used them to design an improved window net mounting system for the 2013 season.
2014-03-10
Article
Jesse Garant & Associates (JG&A) Metrology Center offers industrial CT scanning focused on 3-D internal part inspection services using industrial computed tomography equipment.
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