Display:

Results

Viewing 271 to 300 of 8706
2014-04-01
Journal Article
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.
2014-04-01
Journal Article
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.
2014-04-01
Journal Article
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.
2014-04-01
Journal Article
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
Journal Article
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
Journal Article
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
Journal Article
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
Journal Article
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
Journal Article
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.
2014-04-01
Technical Paper
2014-01-0022
Youichi Kamiyama
Abstract Tire cavity noise has long been one of the main road noise issues. Various ideas for devices to reduce tire cavity noise have been patented or discussed in technical reports, but many issues remain for commercialization, and at present only some tires have appeared as products. Therefore, technology was developed for mounting Helmholtz resonators on the wheels, enabling reduction of tire cavity noise without placing restrictions on the tires. The advantage of this technology is that the cost and productivity targets needed for mass production can be satisfied without impairing the tire and wheel functions. The aim of this development was to construct low-cost device technology that is well-suited to mass production and enables reduction of tire cavity noise to an inaudible sound pressure without adversely affecting dynamic product marketability such as strength and durability performance and handling performance.
2014-04-01
Technical Paper
2014-01-0002
Marcus Becher, Stefan Becker
Abstract This paper focuses on the applicability of numerical prediction of sound radiation caused by an axial vehicle cooling fan. To investigate the applicability of numerical methods, a hybrid approach is chosen where first a CFD simulation is performed and the sound radiation is calculated in a second step. For the acoustic simulation an integral method described by Ffowcs-Williams-Hawkings is used to predict the sound propagation in the far-field. The simulation results are validated with experiments. The corresponding setup in experiments and simulation represents an overall system which includes the cooler, the cooling fan and a combustion engine dummy. To optimize the economical applicability in terms of simulation setup and run time, different approaches are investigated. This includes the simulation of only one blade using a periodic boundary condition as compared to the whole fan geometry. In the CFD simulation an SAS-turbulence-model is applied.
2014-04-01
Technical Paper
2014-01-1293
Gen Shibata, Hirooki Ushijima, Hideyuki Ogawa, Yushi Shibaike
Abstract When fuel is vaporized and mixed well with air in the cylinder of premixed diesel engines, the mixture auto-ignites in one burst resulting in strong combustion noise, and combustion noise reduction is necessary to achieve high load premixed diesel engine operation. In this paper, an engine noise analysis was conducted by engine tests and simulations. The engine employed in the experiments was a supercharged single cylinder DI diesel engine with a high pressure common rail fuel injection system. The engine noise was sampled by two microphones and the sampled engine noise was averaged and analyzed by an FFT sound analyzer. The engine was equipped with a pressure transducer and the combustion noise was calculated from the power spectrum of the FFT analysis of the in-cylinder pressure wave data from the cross power spectrum of the sound pressure of the engine noise.
2014-04-01
Journal Article
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.
2014-04-01
Journal Article
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.
2014-04-01
Journal Article
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
Journal Article
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.
2014-04-01
Technical Paper
2014-01-1680
Sandeep Mahadev Jadhav
Abstract Objective of this research is to reduce gear rattle and whine noise. Study includes measurement of noise, vibration on transmission for source identification in order to eliminate rattle, whine through optimization of gear design and clutch damper performance. In order to optimize, we measured transmission torsional vibration and analyzed for proper selection of clutch dampers to reduce engine vibration transfer function to transmission. Through Noise & Vibration FFT, order and color map analysis we identified noise sources and further scope for specific gears design improvement. Hence test methodology adopted for development of gears and clutch damper successfully eliminated noise.
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.
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.
2014-03-10
Article
CD-adpaco fills the design testing void with multidisciplinary design exploration (MDX), a methodology for automatically testing designs from early in the concept stage.
2014-03-10
Article
NanoFocus’ μsurf cylinder tool, which will be displayed at the SAE 2014 World Congress April 8-10 in Detroit, provides a nondestructive technique for high-resolution 3-D measurements of the inside of cylinder bores and liners.
2014-03-06
WIP Standard
AIR6297
To provide a method for modeling the noise directivity behind start-of-takeoff roll based on empirical data from modern jet aircraft. This method would replace the method described in Section 3.3.1 of SAE-AIR-1845A "Procedure for the Calculation of Airplane Noise in the Vicinity of Airports."
2014-03-06
WIP Standard
AIR6501
To provide a method that accounts for the attenuation due to line-of-sight blockage of aircraft noise by terrain features.
Viewing 271 to 300 of 8706

Filter

Subtopics