Criteria

Text:
Topic:
Display:

Results

Viewing 1 to 30 of 2517
2017-06-05
Technical Paper
2017-01-1872
Masao Nagamatsu
The almost current sound localization methods do not have enough resolution in low frequency sound localization. To overcome this disadvantage, I am now developing a new sound localization method, Double Nearfield Acoustic Holography (DNAH) method. This method is a converted method of conventional Nearfield Acoustic Holography (NAH) method. In this proposing method, the resolution of low frequency sound localization is improved by using sound propagation information on doubled measurement planes. To prove the performance of proposing method, the basic experiments with variable conditions are conducted. In these experiments, the small speakers are used as sound sources. In this paper, to discuss the ability to apply to actual industry, the effect of measurement distance from sound source is explained. Some experimental results with changing measurement distance are shown in this paper.
2017-06-05
Technical Paper
2017-01-1811
Jouji Kimura, Tatsuya Tanaka, kenjiro hakomoto, Kousuke Kawase, Shinichiro Kobayashi
This paper describes based on the mechanism of whirl resonance about the characteristic of serious bending stress which occurred in the crankshaft rear. The following steps to prove that the bending stress is caused by whirl resonance of the crankshaft rear end. At first, the authors showed that the resonance frequency of bending stress for forward whirl which takes place in the same direction as crankshaft rotation increases with the increasing engine speed, and the resonance frequency of bending stress for reverse whirl which takes place in the reverse direction as crankshaft rotation decreases with the increasing engine speed. Secondly, it was found out that there are two groups, the correlation between the resonance frequency and the resonance engine speed of the measured bending stresses in the crankshaft rear. One is the group that the resonance frequency increases with the increasing engine speed.
2017-06-05
Technical Paper
2017-01-1883
Arnaud Duval, Guillaume Crignon, Mickael Goret, Maxime Roux
The lightweighting research on noise treatments since years tends to prove the efficiency of the combination of good insulation with steep insulation slopes with broadband absorption, even in the context of bad passthroughs management implying strong leakages. The real issue lies more in the industrial capacity to adapt the barrier mass per unit area to the acoustic target from low to high segment or from low petrol to high diesel sources, while remaining manipulable. The hybrid stiff insulator family can realize this easily with hard felts barriers backfoamed weighting from 800 g/m² to 2000 g/m² typically with compressions below 10 mm. Above these equivalent barrier weights and traditional compressions of 7 mm for example, the high density of the felts begins to destroy the porosity and thus the absorption properties (insulation works anyway here, whenever vibration modes do not appear due to too high stiffness…).
2017-06-05
Technical Paper
2017-01-1908
Rong Guo, Jun Gao, Xiao-kang Wei, Zhao-ming Wu, Shao-kang Zhang
This work aims to provide theoretical basis for improving engine shake performance based on full vehicle model by optimizing the design parameters of hydraulic engine mounts (HEMs). The definition of the engine shake problem is presented through comparing the quarter vehicle models with the rigid-connected and flexible-connected powertrain which is supported by a rubber mount. Then the model is extended by replacing the rubber mount as a HEM with regard to the inertia and resistance of the fluid within the inertia track. Based on these, a full vehicle model with 14 degree of freedoms (DOFs) is proposed to calculate the engine shake, which consists of 6 of the powertrain, 1 of the fluid within the inertia track of the HEM, 3 of the car body and 4 of the unsprung mass. Parameter study is performed to determine the most effective parameters of the HEM influencing engine shake and then the HEM is optimized through the genetic algorithm (GA).
2017-06-05
Technical Paper
2017-01-1830
Thomas Haase, Henning Bühmann, Martin Radestock, Hans Peter Monner
Due to the strengthened CO2 and NOX regulations future vehicles has to be lightweight and efficient. But, lightweight structures are prone to vibrations and radiate sound efficiently. Therefore, an active approach for reducing sound radiation from structures is the active structural acoustic control (ASAC). Since the early 90’s, several theoretical studies regarding ASAC systems were presented, but only very little experimental investigations can be found for this alternative to passive damping solutions. The theoretical simulations show promising results of ASAC systems compared to active vibration control approaches. So, for that reason in this paper an experiment is conducted to investigate the performance of an ASAC system in the frequency range up to 600 Hz. A regular sensor grid of 24 accelerometers that are interconnected to establish six radiation signals is applied to an aluminum plate.
2017-06-05
Technical Paper
2017-01-1871
Nobutaka Tsujiuchi, Masahiro Akei, Akihito Ito, Daisuke Kubota, Koichi Osamura
This paper describes new method for selecting optimal field points in Inverse-Numerical Acoustic analysis (INA), and an application to construction of sound source model for diesel engine. INA is a method that identifies surface vibration of the sound source by using acoustic transfer functions and actual sound pressures which are measured at field points located near the sound source. In the INA, for measuring sound pressures, it is necessary to determine the arrangement of field points. The increase of field points leads to longer test and analysis time. Therefore, guidelines for deciding field point arrangement are needed to conduct INA efficiently. The authors focused on the standard deviations of distance between sound source elements and field points, and proposed new guideline for optimal selection of the field points, in a past study. In the past study, the effectiveness of this guideline was verified using a simple plate model.
2017-06-05
Technical Paper
2017-01-1848
Richard DeJong
From 1983 to 1995, Richard H. Lyon published several papers on Statistical Phase Analysis, showing that the average phase of the transfer functions in complex systems grows with frequency in proportion to the modal density of the system. In one dimensional systems this phase growth is the same as that of freely propagating waves. However, in two and three dimensional systems this phase growth is much larger than the corresponding freely propagating wave. Recent work has shown that these phase growth functions can be used as mode shape functions in discrete system models to obtain results consistent with Statistical Energy Analysis. This paper reviews these results and proposes naming the statistical mode shape functions in honor of Lyon.
2017-06-05
Technical Paper
2017-01-1819
Cyril Nerubenko, George Nerubenko
The results of dynamical study of new patented Torsional Vibration Dampers mounted on a crankshaft in V8 engines are presented. Design and structure of Torsional Vibration Damper is based on author’s US Patent 7,438,165 having the control system with instantaneous frequencies tuner for all frequencies of running engine. Analysis and disadvantages of conventional rubber and viscous Crank Dampers are shown. The focus of the study is on Torsional Vibration Damper having the mechanical self-tuning structure applicable for V8 engines. Mathematical model based on the system of ordinary differential equations describing the rotation and vibration of mechanical components has been used for the analysis of the dynamic behavior of V8 engine crankshaft system having proposed Torsional Vibration Damper. Attention is paid to composition and selection of optimal parameters of a proposed device for solving the problems of effective mitigation of crankshaft torsional vibrations in V6 engines.
2017-06-05
Technical Paper
2017-01-1840
Thierry Bourdon, Rainer Weber, Johann massinger PhD
Nowadays, the automotive industry is increasingly facing of reducing vibration & noise in the vehicle. More particularly on the engine area, the development of fuel components based on high pressure pumps, rails, any pipes and injectors are a subject of a particular NVH attention. The use of modern digital techniques such as 3D finite element vibroacoustic, leads to use virtual prototyping as complementary to traditional real hardware prototypes development. Among interest, number of iterative loops to reach a best design brings an important value to new product development with an optimized cost. Basically the core part of virtual prototyping is about 3D finite element models for each component. It is quite challenging to establish these models, as they must mimic the entire physical phenomenon of real structure borne hardwares sound in the whole audible frequency range.
2017-06-05
Technical Paper
2017-01-1775
Mark A. Gehringer, Robert Considine, David Schankin
This paper describes recently developed test methods and instrumentation to address the specific noise and vibration measurement challenges posed by large diameter single-piece tubular aluminum propeller shafts with high modal density. The application described in this paper is a light duty truck, although the methods described are applicable to any rotating shaft with similar dynamic properties. To provide a practical example of the newly developed methods and instrumentation, rotating and non-rotating data were acquired in-situ for several propeller shafts of varying construction, including both lined and unlined shafts. Data were also acquired with and without a torsional tuned vibration absorber attached to the driveline. The example data exhibit features that are uniquely characteristic of large diameter single-piece tubular shafts with high modal density, including the particular effect of shaft rotation on the measurements.
2017-06-05
Technical Paper
2017-01-1773
Jing Yuan
The dual phase twin synchronous drive has been developed for belt noise reduction. Two identical synchronous belts are arranged parallel side by side with one tooth staggered against other by the half pitch. The noise cancellation effect is achieved as one belt tooth engagement coincides with the other belt tooth dis-engagement. A center flange is used as a divider to prevent the belts contacting each other along the axial direction during their entrance and exit of the sprocket. An overall 20 [dBA] noise reduction has been achieved with the dual phase twin belt system compared to an equal width single belt counterpart. The vibration amplitude of the hub load is also reduced which is directly correlated to the structural borne noise. Comparing to the related dual phase helical tooth belt, also known as the eagle belt trade marked by Goodyear, the dual phase twin belt is superior in torque carrying capability; and is on par with noise mitigation.
2017-06-05
Technical Paper
2017-01-1785
Paul Bremner, Scott Clifton, Chris Todter
Measurements of interior wind noise sound pressure level have shown that dBA and Loudness are not adequate metrics of wind noise sound quality due to non-stationary characteristics such as temporal modulation and impulse. A surface microphone array with high spatio-temporal resolution has been used to observe the corresponding non-stationary characteristics of the exterior aero-acoustic loading. Wavenumber filtering is used to observe the unsteady character of the low wavenumber aero-acoustic loading components capable of exciting glass vibration and transmitting sound.
2017-06-05
Technical Paper
2017-01-1801
Sivasankaran Sadasivam, Aditya Palsule, Ekambaram Loganathan, Nagasuresh Inavolu, Jaganmohan Rao M
Powertrain is the major source of noise and vibration in commercial vehicles and has significant contribution on both interior and exterior noise levels. Sound intensity mapping technique identifies and quantifies the spatial distribution of energy radiated by powertrain by means of measurements close to its surface. Based on the quantification, noise sources are ranked, through which Oil sump is identified as one of the major contributors for powertrain noise radiation. Accurate prediction of oil sump modal characteristics is more critical in determining the sound power radiation. This paper discusses about capability of numerical approach in predicting more realistically, oil sump modal characteristics with fluid-structure interaction and consequent verification with experimental modal test results. With this validated model, radiated sound power level of the oil sump has been predicted using acoustic finite element method.
2017-06-05
Technical Paper
2017-01-1820
Martin Sopouch, Josip Hozmec, Alessandro Cadario
This paper presents a simulation environment and methodology for noise and vibration analyses of a driven rear axle in a bus application, with particular focus on medium to high frequency range (400 Hz to 3 kHz). The workflow demonstrates structure borne noise and sound radiation analyses. The fully flexible Multi–Body Dynamics (MBD) model - serving to cover the actual mechanical excitation mechanisms and the structural domain – includes geometrical contacts of hypoid gear in the central gear and planetary gear integrated at hubs, considering non-linear meshing stiffness. Contribution of aforementioned gear stages, as well as the propeller shaft universal joint at the pinion axle, on overall axle noise levels is investigated by means of sensitivity analysis. Based on the surface velocities computed at the vibrating axle-housing structure the Wave Based Technique (WBT) is employed to solve the airborne noise problem and predict the radiated sound.
2017-06-05
Technical Paper
2017-01-1761
Daniel Fernandez Comesana, Graciano Carrillo Pousa, Emiel Tijs
The automotive industry is currently increasing noise and vibration requirements of vehicle components. A detailed vibro-acoustic assessment of every supplied element is commonly enforced by most vehicle manufacturers. Traditional End-of-line (EOL) solutions often encounter difficulties adapting from controlled environments to industrial production lines due the presence of high levels of noise and vibrations generated by the surrounding machinery. In contrast, particle velocity measurements performed near a rigid radiating surface are less affected by background noise and they can potentially be used to address noise problems even in such conditions. The vector nature of particle velocity, an intrinsic dependency upon surface displacement and sensor directivity are the main advantages over conventional solutions. As a result, quantitative measurements describing the vibro-acoustic behaviour of a device can be performed at the final stage of the manufacturing process.
2017-06-05
Technical Paper
2017-01-1808
Francis Nardella
In a previous report, it was shown that power transmission through the camshaft reduced the first mode natural frequency of the powertrain and translated its convergence with dominant engine excitatory harmonics to a lower engine speed resulting in a marked reduction in torsional vibration for geared 6 cylinder compression ignition engines for aviation. This report describes a sweep though 2 and 4 stroke engines with differing numbers of cylinders configured as standard gear reduction (SGRE) and with power transmission through the camshaft (CDSE). Four and 6 cylinder engines were modeled as opposed boxer engines and 8, 10 and 12 cylinder engines were modeled as 180-degree V-engines. Mass-elastic models of the different engine power train configurations were modeled using the torsional vibration module in Shaft Designer obtained from SKF (Svenska Kullagerfabriken). Crankshaft, camshaft, gearing, pistons, piston pins and connecting rods with bolts were modeled in Solidworks.
2017-06-05
Technical Paper
2017-01-1856
Junji Yoshida, Koki Tanaka, Rie Nakamoto, Ken Fukasawa
Operational transfer path analysis (TPA) is one of TPA methods recently developed. This method calculates contributions of reference points (e.g., engine mount) to the response point (e.g., vehicle interior noise/vibration) using only the operational data. Through this operational TPA (OTPA), effective noise/vibration reduction can be achieved. On the other hand, many accurate vibraton modes can be obtained recently by the progress of CAE technique. However, it is not eacy to find out which calculated vibration modes of the structure (e.g., vehicle flame) affect the response point (e.g., steering) largely. In this study, we then combined the OTPA technique with CAE to obtain high contributing mode. As the test structure, a rear flame of a small constraction machine model was employed. Firstly, the vibration modes were obtained by CAE (eigenmode analysis) and 25 modes were obtaiend under 250 Hz. Subsequently, operational vibration of the structure was measured.
2017-06-05
Technical Paper
2017-01-1804
Chulwoo Jung, Hyeon Seok Kim, Hyuckjin Oh, Kwang Hyeon Hwang, Hun Park
An efficient method to determine bush stiffness of passenger cars for satisfying requirement of noise and vibration is developed. In general, a passenger vehicle includes various types of bush to connect systems and control forces (loads) transferred between systems which affect characteristics of noise and vibration of the vehicle. Noise and vibration of a vehicle are mainly caused by forces from power train (engine and transmission) and road excitation. While a vehicle is in operation, road excitation is applied to the vehicle through bushes. If a bush transfers less force to the body structure, levels of noise and vibration will be decreased. In other words, it is necessary to well determine characteristics of bushes when developing passenger vehicles. Bush stiffness is one of key factors to affect the performance of noise and vibration of the vehicle.
2017-06-05
Technical Paper
2017-01-1859
Filip Franek, Jungu Kang, Jeon Uk, Sunguk Choi
Abstract: Structure-born vibrations are often required to be localized in a complex structure, but in such dispersive medium, the vibration wave propagates with speed dependent on frequency. This property of solid materials causes an adverse effect for localization of vibrational events. The cause behind such phenomena is the propagating wave envelope that changes its phase delay and amplitude in time and space as it travels in dispersive medium. This problem was previously approached by filtering a signal to focus on frequencies of the wave propagating with similar speed, what improved accuracy of cross-correlation results. However, application of this technique has not been researched for localization of vibrational sources by a localization technique. In this work we take advantage of filtering prior to cross-correlation calculation while using multiple sensors to indicate approximate location of vibration sources.
2017-06-05
Technical Paper
2017-01-1892
Yosuke Tanabe, Masanori Watanabe, Takafumi Hara, Katsuhiro Hoshino, Akira Inoue, Masaru Yamasaki
Predicting vibration of motor gearbox assembly driven by a PWM inverter in an early development stage is demanding, because the assembly is one of the dominant noise sources of electric vehicle (EV). In this paper, we propose a simulation model that can predict the transient vibration excited by gear meshing, reaction force from mount and electromagnetic forces including carrier frequency component of inverter up to 10 kHz. By employing the techniques of structural model reduction and state space modeling, the proposed model enables to predict the vibration of assembly in operating condition to simulate with a system level EV simulator. A verification test was conducted to compare the simulation result with running test result of EV. Although the absolute value of simulation is 10 dB different from test at most, we conclude that the model can well predict the trend of the dominant order vibration caused by the electromagnetic force of motor including the carrier frequency of inverter.
2017-06-05
Technical Paper
2017-01-1822
Kopal agarwal, Sandip Hazra
Vehicle Drive away shudder is a vibration felt by customers at the time of marching off. The vibration is significantly felt at the time of Clutch Engagement as a shiver in vehicle. While the known reason of Shudder is clutch friction & engagement, in this study we have provided a solution to reduce the shudder by optimizing the power train mounting system. The shake occurs at approximately 10-20kmph in a medium sized car. The design of powertrain mounting system has been modified to achieve the reduction in shake. The pros & cons of the said change in mounting system on the overall NVH performance is also discussed.
2017-06-05
Technical Paper
2017-01-1780
Yong Xu
Research Objective: For MT vehicles, gearbox rattle is a common NVH problem which influences the comfort level of vehicle. In order to prevent rattle in the design phase of vehicle, this work aimed to study the excitation mechanism and influence factors of gearbox rattle, and then to propose effective measures. Methodology: First, the root cause of gearbox rattle problem was studied with the aid of classical dynamical theories. And then the simulation model of vehicle powertrain system was built via Matlab-Simulink. Then some critical parameters of the model and some experiential optimum proposals were selected to perform a sensitivity analysis on the torsional vibration, which is the root cause of rattle. Referring the simulation results, the dual-mass flywheel was selected as the most effective solution to gearbox rattle. Results: The simulation results indicated the critical parameters for optimization to prevent gearbox rattle problem in the design phase of the vehicle.
2017-06-05
Technical Paper
2017-01-1768
Yong Xu
Purpose: For rear-wheel-drive (or all-wheel-drive) vehicles, the vibration and noise that caused by driveshaft often become the main factors that influence the comfort level of vehicle. In order to control and improve the NVH problems related to driveshaft, this work aimed to study the excitation mechanism and transfer path of driveshaft vibration, and then to propose effective measures. The purpose of this work was to propose an effective way to improve the NVH performance by controlling the additional excitation force of U-joints in the early phase of project. Methodology: First, the rotation order characteristics of driveshaft were studied with the aid of classical dynamics. Then a rigid-elastic coupling model of vehicle powertrain was modelled with the theory of multi-body dynamics. By inputting the actual vehicle parameters into the model, the acceleration operation of vehicle could be simulated.
2017-06-05
Technical Paper
2017-01-1799
Nagasuresh Inavolu, Jaganmohan Rao M, S. Nanda kumar, J lingeshkumar, Akshay Loya, mvgprasad mv
Engine noise reduction is one of the highest priorities in vehicle development from the viewpoint of meeting stringent noise regulations. Engine noise reduction involves identification of noise sources and suppression of noise by changing the response of sources to input excitations. Noise can originate from several mechanical sources in engine. The present work focuses on systematic study of the behavior or response of engine structure and its ancillaries to engine excitation and thereby assess their contribution to overall engine noise. The approach includes engine noise and vibration measurement and component ranking using engine noise and vibration measurement in a non-anechoic environment, structural analysis of engine including experimental modal testing of engine and the components, noise transfer function measurements of engine components. Correlation of the obtained results is performed to identify the noise sources.
2017-06-05
Technical Paper
2017-01-1803
John Van Baren
The accumulated damage that a product experiences in the field due to the variety of vibration stresses placed upon it will eventually cause failures in the product. The failure modes resulting from these dynamic stresses can be replicated in the laboratory and correlated to end use environment to validate target reliability requirements. This presentation addresses three fundamental questions about developing accelerated random vibration stress tests. Question#1: What random profile is needed (and for how much time) to accurately simulate the end use environment over the life-cycle of my product? Question #2: My product operates in many different vibration environments, how can I confidently combine them into one accelerated test?Question #3: How can I use the FDS to accelerate my test?
2017-06-05
Technical Paper
2017-01-1752
Kapil Gupta, Arun Choudhary, Rakesh Bidre
At present, a Dual Mass Flywheel (DMF) system is widely known to provide benefits on driveline induced noise, vibration and drivability over a Single Mass Flywheel (SMF). A well-tuned DMF provides nice isolation of torsional vibrations generated in periodic combustion process of automobile IC engines. Similarly, a torsional vibration damper mounted on driveline component reduces the torsional excitation and results a lower torsional vibration at driveline components. Noise and vibration issues like boom noise and high vibrations at low engine rpm range drive are often resulted due to high engine firing order torsional excitation input to the driveline. More often, this becomes one of the most objectionable noise and vibration issues in vehicle and should be eliminated or reduced for better NVH performance. A 4 cylinder, 4 stroke small diesel engine equipped with SMF is found to have high engine firing order torsional excitation.
2017-06-05
Technical Paper
2017-01-1891
Todd Freeman, Kelby Weilnau
Similar to the automotive industry, the expectations from customers for the noise and vibration performance of personal vehicles such as golf carts, ATV’s, and side-by-side vehicles has continued to evolve. Not only do customers expect these types of vehicles to be more refined and to have acoustic signatures that match the overall performance capabilities of the vehicle, but marketing efforts continue to focus on product differentiators which can include the acoustic and vibration performance. Due to this increased demand for acoustic and vibration performance, additional NVH efforts are often required to meet these expectations. This paper provides a sample of some of the efforts that have occurred to further refine and develop the noise and vibration signature for golf carts.
2017-06-05
Technical Paper
2017-01-1850
Samaneh Arabi, Glen Steyer, Zhaohui Sun, Jeffrey Nyquist
The Environmental Protection Agency (EPA) requirement for 54.5mpg by 2025 to reduce greenhouse gases has pushed the industry to look for alternative fuels to run vehicles. Electricity is of those green energies that can help auto industry to achieve those strict requirements. However, the electric or hybrid-electric vehicles brought new challenges into science and engineering world including the Noise and Vibration issues which are usually tied up with both airborne and structural noises. The electromagnetic force plays a significant role in acoustic noise radiation in the electric motor which is an air-gap radial Maxwell force. This paper describes an innovative approach to model the physics of noise radiated by the electric motor.
Viewing 1 to 30 of 2517

Filter

  • Range:
    to:
  • Year: