Display:

Results

Viewing 211 to 240 of 8654
Technical Paper
2014-04-01
Kwang-Ho Oh, Won Hee Han, Jun-Ho Jang, Yong-Choo Tho, Hak Hyun Kim
Abstract Light weighting is a critical objective in the automotive industry to improve fuel efficiency. But when redesigning parts for light weight, by changing from metal to plastic, the resulting design gives NVH issues due to differences in part mass and material stiffness. Many parts were not converted from metal to plastic because of NVH issues that could not be solved. Many engine parts such as cylinder head cover, air intake manifold, oil pan and etc. previously made of metal have since long been replaced with plastic. But timing chain cover has not been replaced because of the aforementioned issue. Sealing performance due to the dynamic characteristics of the application is another challenging factor. In this paper, the key aspects of the plastic timing chain cover as well as its advantage are presented.
Technical Paper
2014-04-01
Giovanni Morais Teixeira
Abstract Fatigue caused by forced vibration of a random nature is one of the major concerns in the automotive field. Random loading of components under actual driving conditions causes dynamic stress/strain responses which can be better described and handled in the frequency domain. Power Spectrum Density (PSD) is usually the most concise and straightforward way of representing a random process. Since frequency domain methodologies are gaining more respect and interest it is very important to be aware of their limitations and scope, particularly when compared to time domain algorithms. The present paper aims to discuss both approaches and establish some comparisons in terms of accuracy, range of application, computation time and user friendliness.
Technical Paper
2014-04-01
Shuming Chen, Dengzhi Peng, Dengfeng Wang
Abstract Automobile cabin acoustical comfort is one of the main features that may attract customers to purchase a new car. The acoustic cavity mode of the car has an effect on the acoustical comfort. To identify the factors affecting computing accuracy of the acoustic mode, three different element type and six different element size acoustic finite element models of an automobile passenger compartment are developed and experimentally assessed. The three different element type models are meshed in three different ways, tetrahedral elements, hexahedral elements and node coupling tetrahedral and hexahedral elements (tetra-hexahedral elements). The six different element size models are meshed with hexahedral element varies from 50mm to 75mm. Modal analysis test of the passenger car is conducted using loudspeaker excitation to identify the compartment cavity modes. All the acoustic cavity models are coupled with the structure model respectively, the cavity modes are calculated with structural-acoustic coupling model.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
Prasad Kumbhar, Ning Li, Peijun Xu, James Yang
In vehicle driving environment, the driver is subjected to the vibrations in horizontal, vertical, and fore-aft directions. The human body is very much sensitive to whole body vibration and this vibration transmission to the body depends upon various factors including road irregularities, vehicle suspension, vehicle dynamics, tires, seat design and the human body's properties. The seat design plays a vital role in the vibration isolation as it is directly in contact with human body. Vibration isolation properties of a seat depend upon its dynamic parameters which include spring stiffness and damping of seat suspension and cushion. In this paper, an optimization-based method is used to determine the optimal seat dynamic parameters for seat suspension, and cushion based on minimizing occupant's body fatigue (occupant body absorbed power). A 14-degree of freedom (DOF) multibody biodynamic human model in 2D is selected from literature to assess three types of seat arrangements. The human model has total mass of 71.32 kg with 5 body segments.
Technical Paper
2014-04-01
Jong Ho Lee
Abstract Since vehicle NVH reduction technology has improved dramatically, buzz, squeak and rattle (hereafter referred to as “BSR”) noise quantification from interior and exterior of the vehicle becomes an important factor to measure the quality of the vehicle. (The cost rate of BSR noise claims take around 10-15%, moreover BSR noise negatively affects customers to purchase vehicles.) Therefore, a research of BSR evaluation comes to the fore to make a premium car. In this paper, we would like to introduce the development of a vehicle excitation test mode, the full-vehicle BSR test system, and a sound acoustic camera to detect BSR noise. The test profiles were correlated with various road severities such as the domestic field test sites including 5,000km cross-country off road, 19 test tracks for BSR in R&D test center, and quality test tracks in domestic factories. These test modes were classified into 4 levels (Low-Normal-High-Crazy) by judging degrees of GRMS values. The full-vehicle test system can reproduce various field road profiles of the BSR for chassis parts, interior, and exterior for temperatures of −40∼60°C.
Technical Paper
2014-04-01
Hiroyuki Tanaka, Hisashi Ihara, Akira Satomura, Yasuhiko Wada, Hideto Momii, Tatsuya Suma
Abstract In order to enhance product attraction, it is important to reduce the impact noise when a vehicle go over bumps such as bridge joints. Vehicle performance to transitional noise phenomena is not yet analyzed well. In this paper, a prediction method is established by vector composition and inverse Fourier transform with the combination of Multibody Dynamics (MBD) and FEM. Also, a root cause analysis method is established with the following three mechanism analysis methods; transfer path analysis, mode contribution analysis, and panel contribution analysis.
Technical Paper
2014-04-01
Li Yan, Weikang Jiang, Jiangqi Zhou
Abstract Sound quality of vehicle interior noise affects passenger comfort. In order to improve the sound quality of a micro commercial vehicle, the vehicle interior noise under different conditions such as idle, constant speeds and accelerating is recorded by using artificial head with dual microphones. The sound quality of recorded noise is evaluated in both objective and subjective ways. Physical parameters of interior noise are calculated objectively, and annoyance score is analyzed subjectively using paired-comparison method. According to the regression analyzing of the annoyance score and the physical parameters, an objective evaluation parameter of the sound quality is employed. To analyze the vehicle body panel contribution to interior noise sound quality, the location and spectrum characteristics of major panel emission noise sources are identified based on partial singular valued decomposition (PSVD) method. By investigating the contribution of each noise sources to the sound quality evaluation formula, the dominant interior noise source is determined.
Technical Paper
2014-04-01
Eric Frank, Peter Jacobsen
Abstract As the demand for Sound Quality improvements in vehicles continues to grow, robust analysis methods must be established to clearly represent end-user perception. For vehicle sounds which are tonal by nature, such as transmission or axle whine, the common practice of many vehicle manufacturers and suppliers is to subjectively rate the performance of a given part for acceptance on a scale of one to ten. The polar opposite of this is to measure data and use the peak of the fundamental or harmonic orders as an objective assessment. Both of these quantifications are problematic in that the former is purely subjective and the latter does not account for the presence of masking noise which has a profound impact on a driver's assessment of such noises. This paper presents the methodology and results of a study in which tonal noises in the presence of various level of masking noise were presented to a group of jurors in a controlled environment. Their subjective ratings were collected and correlated to noise and vibration metrics.
Technical Paper
2014-04-01
Adarsh Venkata Padmanabhan, Hariram Ravichandran, Lokendra Pavan Kumar Pappala, Rangaraj Ramanan Durai
Abstract This paper will discuss information extraction from sound signals obtained using acoustic sensors which are strategically placed on the automotive body. The sound signal obtained contains useful information such as vehicle and road surface characteristics. The aforementioned information was spread out at different frequencies in the spectral distribution of the signal. Well defined filters for the corresponding frequency bands were used to isolate these characteristics and patterns pertaining to the identified useful information from the signal. The obtained information can be used as inputs for systems such as vehicle safety systems, power train systems and NVH (Noise, Vibration and Harshness) systems.
Technical Paper
2014-04-01
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. The parameters investigated in the engine tests were the maximum rate of pressure rise, intake pressure by the supercharger, intake oxygen content by EGR, and the fuel injection timing, in all experiments the engine speed was maintained at 1600 rpm.
Technical Paper
2014-04-01
Jeremie Dernotte, John 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.
Technical Paper
2014-04-01
Julie Blumreiter, Chris Edwards
Abstract There is significant motivation to extend the operating range of naturally aspirated HCCI combustion to high load (8-12 bar IMEP) to attain a combustion strategy with the efficiency benefits of HCCI but without the lost power density of a lean or highly diluted charge. Currently, the high-load limit of HCCI combustion is imposed by a phenomenon commonly known as ringing. Ringing results when the kinetically-driven autoignited combustion process proceeds in such a way as to form strong pressure waves which reverberate in the engine. Inhomogeneities and gradients in mixture reactivity lead certain regions to react ahead of others, and as a result, coupling can occur between a pressure wave and the reaction front. This paper seeks first to sort several related but distinct issues that impose the high load limit: ringing, engine damage, peak in-cylinder pressure, peak rate of pressure rise, and engine noise. The fundamental gasdynamics underlying the upper load limit for premixed, autoignited engines are explored and elucidated with a quasi-1D reacting compressible flow model.
Technical Paper
2014-04-01
Se Jin Park, Seung Nam Min, Murali Subramaniyam, Heeran Lee, Dong Gyun Kim, Cheol Pyo Hong
Abstract Vibration is both a source of discomfort and a possible risk to human health. There have been numerous studies and knowledge exists regarding the vibrational behavior of vehicle seats on adult human occupants. Children are more and more becoming regular passengers in the vehicle. However, very little knowledge available regarding the vibrational behavior of child safety seats for children. Therefore, the objective of this study was to measure the vibrations in three different baby car seats and to compare these to the vibrations at the interface between the driver and the automobile seat. The test was performed on the National road at the average speed of 70 km/h and acceleration levels were recorded for about 350 Sec (5.83 min). One male driver considered as an adult occupant and a dummy having a mass of 9 kg was representing one year old baby. Four accelerometers were used to measure the vibration. All measured accelerations were relative to the vertical direction. Vibration Analysis Toolset (VATS) was used for time domain analysis.
Collection
2014-04-01
This technical paper collection covers intake/exhaust/powertrain and chassis noise and vibration.
Collection
2014-04-01
This technical paper collection sets out to reflect the recent advances on the research, development and practices of Powertrain NVH treatment. The coverage includes: engine, engine subsystem and components noise and vibration; powertrain systems noise measurement and instrumentation; powertrain systems noise analysis.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Technical Paper
2014-04-01
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.
Viewing 211 to 240 of 8654

Filter

  • Article
    874
  • Book
    22
  • Collection
    16
  • Magazine
    252
  • Technical Paper
    6902
  • Standard
    588
  • Article
    588

Subtopics