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Viewing 1 to 30 of 594
2011-04-12
Technical Paper
2011-01-0499
Jia-Shiun Chen, Hsiu-Ying Hwang
The Taipei Metro is one of the major transportation systems in the Taipei area. Noticeable noise and vibration caught attention during the train turning on a rail with a large angle. The initial investigation indicates the noise occurs between the slewing ring bearing and the friction sets which are located between the body and chassis systems. A study was conducted to identify the root causes. A lab test to duplicate the reported problem observed on the train was established, and a set of experiments were performed in the lab to identify the root causes. Under certain contact conditions, unsmooth turning would occur and cause the noise and vibration. To further identify and understand the root causes. An ADAMS multibody dynamic model which included the slew bearing and friction set was build to perform the train turn motion, and to verify the lab test. Different friction materials were also included in the simulation.
2013-05-13
Technical Paper
2013-01-1963
Richard Kolano
This paper presents the design, construction, and implementation of a novel sound transmission loss (STL) testing fixture that is unique to the automotive industry. This fixture was built within a large 1.68 m high × 2.74 wide (5′6″ × 9′0″) opening in the wall between a 497 m3 (17,591 ft3) reverberation room and an adjacent anechoic chamber. The fixture was designed and built to accommodate interchangeable plugs that allow STL measurements on an automotive ‘buck’ as well as on flat sample materials. It features a removable sample holding frame system that simply and quickly clamps in place and acoustically seals with a pneumatically inflated seal.
2013-05-13
Technical Paper
2013-01-1946
Michael Fasse
The use of acoustic cavity fillers to prevent the propagation of air borne and structure borne noise, water and dust into the interior spaces of vehicle structures has been in practice for many years. Various technologies are available to OEMs to provide sealing that will prevent water and dust penetration, maximize performance of vehicle HVAC systems, and minimize the propagation of noise into a vehicle under operating conditions. The current state of the application of these technologies in the automotive, medium duty and heavy duty truck markets will be reviewed. Comparisons will be drawn between two categories of cavity fillers: pre-formed heat reactive expandable parts; and bulk applied chemically reacting polyurethane foam. Typical OEM material requirements will be discussed for these technologies. The pros and cons of these competing technologies, as well as their acoustic performance applied to a full vehicle will be considered.
2013-05-13
Technical Paper
2013-01-2008
Steven Jorro, John Zehme, Sam Mleczko, Eglind Myftiu, Blake Rager
The reduction of full acceleration truck pass-by noise conforming to Type ECE-51 regulation (Reference 1) was predicted in a hemi-anechoic chassis dynamometer chamber with microphone arrays and compared with actual test track results. This gave a close match to the track data, with both showing a 4 dB reduction in the A-weighted overall noise level after identical acoustic treatments were applied. Noise control materials were selected to perform as acoustic barriers and absorbers. These were optimized by analyzing the 1/3 octave spectra, determining dominant frequency bands, in critical source locations and engine speeds, and using combinations that dissipate or contain energy well within those bands. With the truck being stationary while tested, important source locations could be quickly identified both subjectively and with localization tools such as Beamforming.
2013-09-24
Technical Paper
2013-01-2382
Venkatesh Narayanan, Karalmarx R, Sai Sankaranarayana, Kalyankumar Hatti
The Bogie suspensions ensure better stability at higher loads and also give the utmost reliability under extreme climatic conditions with minimum maintenance. Many vehicle manufactures have adopted for the bogie suspension at rear based on its advantages. The noises generated from the vehicle in the field includes engine noises and flow noises and hence it is very difficult to clearly discern the noise generated from suspension system of the vehicle [1]. Most suspension system noises do not come from a single part but they are caused by the coupling action between related parts, making it difficult to clearly identify the exact cases. This paper details the overall approach to identify the bogie suspension noise on a commercial vehicle and countermeasures to reduce the same.
2013-09-24
Technical Paper
2013-01-2343
Arunkumar Sengottuvel, Muralidharan Chennakrishnan, Kalyankumar Hatti
Transfer function measurements are the basis for construction of conventional test based source-path-receiver model of a vehicle. Interior noise of a vehicle can be synthesized using source excitation (both acceleration at source and near source sound pressure level) and its corresponding transfer function (Vibro-Acoustic Transfer Function (VATF) and Acoustic Transfer Function (ATF) respectively) to the interior of vehicle. Ideally ATF should be linear and independent of sound source, dependent only on size of air cavities, body structure and its material characteristics in between receiver and source location. But practically because of the type of excitation signal used to excite the sound source and characteristics of sound source itself, there is a possibility of variations in amplitude of acoustic transfer function.
2013-09-24
Technical Paper
2013-01-2342
Ravindran V, B. Prakash
This paper deals with the techniques of reducing noise in agricultural tractors. Noise reduction in agricultural tractors is an emerging concern and apart from meeting the noise norms it helps in increasing the productivity of farmers. Noise is also a factor affecting the health of the farmers. Two major European regulatory requirements are driver ear noise level and passer by noise level. Of the two regulatory requirement, driver ear noise is critical, since the limit is 86 dB (A) compared to 89 dB (A) of passer by noise limit which is measured at 7.5 meters from tractor. Various strategies for noise reduction are discussed in this paper including reduction at source level and passive solutions. Passive solutions are used where the timeline for development is short. Various passive solutions like acoustic foam design are discussed. Finally with the combination of active and passive solutions, driver ear noise target was met successfully.
2004-10-26
Technical Paper
2004-01-2694
Stefano J. Cassara, David C. Anderson, J. Magnus Olofsson
The accurate prediction of commercial-vehicle ride and handling performance with computer simulation tools is dependent on the level of correlation between the computer model and experimental data. Correlating vehicle attributes to physical test data is often challenging due to the large number of degrees of freedom - and, correspondingly, the large number of tunable parameters - typically required to accurately model vehicle behavior. A high level of interaction between input parameters and vehicle attributes further complicates the task. As a result, this type of correlation is a multi-objective optimization exercise in which the judicious planning of supporting test activity is critical to achieving the right level of model accuracy with an acceptable amount of resource investment. This paper discusses the methodology implemented in the validation of a tractor-semitrailer ADAMS model for both ride and handling simulations and presents the results obtained.
2004-10-26
Technical Paper
2004-01-2655
Robert Rahmfeld, Monika Ivantysynova, Bastian Eggers
This paper deals with the use of a displacement controlled linear actuator for active oscillation damping of off-road machine structure. Aim is the development of system solutions and control concepts for the simultaneous use of displacement controlled (valveless) hydraulic actuators basing on single rod cylinder for the active oscillation damping of off-road machine structure and for the control of the working hydraulics movement. Thereby, the productivity of the machine and the operator comfort will be improved.
2013-01-09
Technical Paper
2013-26-0103
P. S. Yadav, A. A. Gaikwad, S. Y. Badgujar, Y. V. Surkutwar, N. V. Karanth
High noise at Operator Ear Level (OEL) of tractor is the major cause of fatigue to the operator. With growing competition, and upcoming legislative requirement there is ominous need for the agricultural tractor manufacturers to control noise levels. Objective of the present study is noise reduction on agriculture tractor by identifying and controlling key noise sources unaffecting performance parameters like power, torque and fuel efficiency to meet upcoming noise legislations. Noise Source Identification (NSI) is carried out to identify and rank airborne and structure borne noise sources. The airborne sources such as cooling fan, exhaust silencer and intake are evaluated using elimination method at tractor level. The NSI on engine is carried out separately in hemi anechoic chamber to identify the major noise radiating components by using noise and vibration measurement, sound intensity mapping tools.
2013-10-07
Technical Paper
2013-36-0469
Paulo Alexandre Galarce Zavala, José Roberto de França Arruda, Fábio Gimenes Bueno, Gaetano Miranda, Waldir Mothio, Camilo Abduch Adas
Due to increasingly stringent laws regarding the level of noise emitted by motor vehicles, especially when it comes from trucks, many techniques are used to determine the main source of noise. Levels must meet the standard pass-by noise as provided by the standard ISOR362. This work applies a technique that aims to identify the main source of noise of heavy vehicles during the pass-by noise test, called Pass-by Noise Beamforming. The technique use the method known as Generalized Inverse and an array of microphones optimized for low frequencies. The paper presents the steps of validation of the system using loudspeakers and application in two trucks with distinct contributions (engine and tire noise). The results of the technique showed advantages compared to the conventional method (delay-and-sum algorithm), obtaining better separation of coherent sources with better dynamic range in a wide frequency range (50 Hz - 7 kHz).
2011-05-17
Technical Paper
2011-01-1531
Michael Thivant, pascal BOUVET PhD, Alexandre Carbonelli
Due to the increasing focus on noise and vibration for future vehicles, there is a need for a clear definition of the requirements between vehicle manufacturers and auxiliary suppliers. Auxiliary characterisations are also needed as input for structure-borne numerical prediction models. Strongly coupled systems are amongst the most difficult structure-borne noise issues, as the transmitted forces and powers are strongly dependent upon the mobilities of both the vibration source and receiver. The so-called “blocked forces” can be used as intrinsic source descriptions. The challenge is then to design auxiliary test benches perfectly rigid in the frequency range of interest. The current paper is based on the French research program MACOVAM dedicated to the vibro-acoustic characterisation of oil pumps for truck engines. An original test bench was designed to measure quasi-blocked forces over the [150 Hz-2800 Hz] frequency range.
2011-09-13
Technical Paper
2011-01-2241
Shuming Chen, Dengfeng Wang, Jiqiang Song, Gangping Tan, Bingwu Lu
The basic theory of statistical energy analysis (SEA) is introduced, a commercial heavy duty truck cab is divided into 35 subsystems applying SEA method, and a three dimensional SEA model of the commercial heavy duty truck cab is created. Three basic parameters including modal density, damping loss factor and coupling loss factor are calculated with analytical and experimental methods. The modal density of the regular wall plate of the cab is calculated with traditional formula. The damping loss factors of the regular and complicated plates are obtained using analytical method and steady energy stream method. Meanwhile, the coupling loss factors of structure-structure, structure-sound cavity, and cavity-cavity are also calculated. Four kinds of excitations are in the SEA model, including sound radiation excitation of engine, engine mount vibration excitation, road excitation and wind excitation.
2011-05-17
Technical Paper
2011-01-1731
Steven R. Sorenson, Steven Jorro, James Knittel, Christopher Waltenberry
Governmental regulations regarding exterior noise emitted by motor vehicles vary throughout the world. A vehicle which is compliant in one market may not be compliant in another market. In this case, a production North American class 8 truck was being prepared for sale overseas. The requirement to meet European Union (EU) pass-by regulations as tested per the EU standard meant development of a production feasible package to substantially reduce noise emissions without changing any fundamental design or operating parameters of the truck. The development testing was done on a chassis dynamometer in a hemi-anechoic chamber without any specific pass-by noise simulation software. Efforts to develop a reasonably accurate correlation from lab to track, use of acoustic beamforming for source localization and package design iterations leading to a final successful package are discussed.
2011-05-17
Technical Paper
2011-01-1730
Glenn Pietila, Gabriella Cerrato, Brad Tadlock, Brian Kascht, Shawn Entriken
As an agricultural tractor OEM was moving a new tractor model from development into production, an objectionable cab “boom” was identified that was not present in the preproduction pilot -level tractors. The cab boom was identified as a low frequency tone causing an increase of 7 (dBA) over the level in the pilot tractors, which was deemed unacceptable. The process used by the tractor OEM engineering team to address this problem has been widely used and refined in the automotive industry, but it is relatively new in the agricultural/off-road vehicle industry. This paper describes the source-path-receiver approach that led to identifying the exhaust tip as the source and the vibro-acoustic coupling of a windshield structural mode with an acoustic cab cavity mode as the path of the boom event.
2011-05-17
Technical Paper
2011-01-1732
David Copley, D. W. Herrin, Harvind Raman, Jiantie Zhen
Properly characterizing input forces is an important part of simulating structure-borne noise problems. The purpose of this work was to apply a known force reconstruction technique to an earthmoving machinery cab to obtain input functions for modeling purposes. The technique was performed on a cab under controlled laboratory conditions to gain confidence in the method prior to use on actual machines. Forces were measured directly using force transducers and compared to results from the force reconstruction technique. The measured forces and vibrations were used as input power to an SEA model with favorable results.
2011-05-17
Technical Paper
2011-01-1670
Logesh Kumar Natarajan, Sandeep Mylavarapu, Sean F. Wu
This paper presents an experimental study on using the Helmholtz equation least squares (HELS) based nearfield acoustic holography (NAH) method for reconstructing the vibro-acoustic responses on the surfaces of arbitrarily-shaped structures. Specifically, we demonstrate the capability of HELS to reconstruct normal surface velocity (NSV) and perform panel contribution analysis. The test object is a hexagonal-shaped structure made of eight panels and frames that mimic a scaled automotive passenger compartment. The test was conducted inside a fully anechoic chamber with the structure excited by a point force using random input signals. The radiated acoustic pressures were measured via a linear array of microphones at a very close distance to the structural surfaces, and taken as the input to the HELS codes to reconstruct NSV and surface acoustic pressures (SAP).
2011-05-17
Technical Paper
2011-01-1612
Dan Faylor
As North American truck manufactures have entered the global market it has become apparent that there are widely varying drive-by noise regulations required in various areas of the world. This paper will describe differences between various test procedures, track layouts, and required levels. Data will be presented showing vehicle results from various procedures, used to quantify differences in noise levels between a range of procedures. Countries were ranked from least restrictive to most restrictive based on test procedures and legal market requirements.
2010-10-17
Technical Paper
2010-36-0511
Andre Oliveira, Lucas Coser, Vinicius Porto
Methods for determining the acoustic absorption coefficient of materials are broadly known in NVH engineering and traditionally rely on measurements performed in specimens carefully prepared such as those used in the Kundt's tube. It is understood that the acoustic behavior of a material slice in a well-controlled test bench provides very different circumstances from those found when the material is used in its application location (in situ condition) mostly because of the structural interactions and the boundary conditions involved. Many questions arise when the goal is to understand which absorbing material will be more effective and, moreover, if its cost is worth enough to solve particular noise issues. To answer those questions, acoustic impedance determination using direct particle velocity measurements were used in this work, in which several absorbing coatings used in specific regions of Brazilian truck cabins were mapped and compared.
2000-03-06
Technical Paper
2000-01-0645
Kohei Kawai, Yoshiyuki Matsuoka
Against discomfort of vehicles for wheelchair users, countermeasures such as a vibration absorber are required. To determine the optimal characteristics of the absorber, we had proposed the Comfort Evaluation Prediction System (CEPS) that can predict subjective evaluation from floor vibration, considering passengers' constitutions and wheelchair types. The purpose of this paper is to construct a model that simulates the vibration transmited to the passenger as part of the CEPS. We modeled a wheelchair-bound passenger and estimated unknown parameters by the result of a modal experiment. Then some simulations were carried out to suggest applicability of the model.
1999-12-01
Technical Paper
1999-01-3085
Frank Leipold, Fábio Gerab, Marco A., Fogaça A.
This work reports the first stage in the experimental optimization of a medium duty truck, equipped with a new engine, with four cylinders and high power, concerning both the noise emission for the environment and the noise level in the passengers' compartment. In the first stage of this work, comparative measurements among the noise levels for vehicles in different configurations were made, in order to identify the most important sources in the vehicle's noise level, as well as to serve as indicative for project improvements. Each system configuration was analyzed separately, in order to obtain a comparative evaluation of the different vehicle configurations along the whole period of measurements.
1999-12-01
Technical Paper
1999-01-3034
Márcio G. Pinto, Felipe Nogueira, Leandro P. de Siqueira
A platform communization is being conducted at VW Truck and Bus aiming at cost reductions. This opportunity is also being used in order to improve the NVH characteristics of the VW commercial vehicles by optimizing engine mounts and other parts. This paper summarizes the procedure followed while optimizing engine mounts and its effect on NVH.
1999-12-01
Technical Paper
1999-01-3062
L. C. Ferraro, M. A. Fogaça, M. Ururahy, M. A. Argentino, A. Costa Neto, T. Adelmann, O.T. Perseguim
1 ABSTRACT The present work describes the modeling and analysis processes of a medium sized truck manufactured in Brazil with regard to comfort behavior. The vehicle model includes Hotchkiss suspensions front and rear with shackle and with a double stage with bump stops at the rear. It is also included frame flexibility in ADAMS, the frame characteristics were imported from a Finite Element Analysis model. Nonlinear shock absorber curves are also represented for the vehicle and cab suspensions. Viscoelastic bushings for cab and powertrain suspension are also included. Random track profile is generated as input and vehicle comfort is described in terms of the ISO 2631-85 Standard. The effect on vehicle comfort of changing a design parameter can be predicted in the model and verified experimentally.
1999-09-14
Technical Paper
1999-01-2817
Subrata Roy, Phillip Cho, Fred Périé
A comprehensive finite element methodology is developed to predict the compressible flow performance of a non-symmetric 7-blade axial flow fan, and to quantify the source strength and sound pressure levels at any location in the system. The acoustic and flow performances of the fan are predicted simultaneously using a computational aero-acoustic technique combining transient flow analysis and noise propagation. The calculated sound power levels compare favorably with the measured sound power data per AMCA 300-96 code.
1999-09-14
Technical Paper
1999-01-2820
Phillip Cho, Arjun Karavadi
Sound quality has become an important factor in determining customer perception of overall vehicle quality and value in the automotive industry [1]. Recently, in the agricultural and construction machinery industry, the concept of sound quality has gained merit as a possible vehicle for delivering quieter products to customers [2]. This paper studies the application of sound quality methodology for agricultural and construction machinery. Accordingly, the state of agricultural and construction machinery sound quality in the market place is evaluated and sound quality metrics that correlate well with the customers' subjective preferences are identified. The relevance of the chosen sound quality metrics is established by combining the results of the listening-jury evaluation and the requirements for product noise control as driven by competition and regulations.
2000-03-06
Technical Paper
2000-01-0036
Kazunari Nakahara, Katsutoshi Ohta
A cylindrical hydraulic engine mount with simple construction has been developed which has a sub chamber formed without diaphragm by utilizing air compressibility. An analysis model of the mount is presented to predict the non-linear dynamic characteristics in consideration of the effect of excitation amplitude on the dynamic stiffness and loss factor. The calculated dynamic characteristics are in good agreement with experimental results. By using the analysis model, the effect of the volume and pressure of air on the dynamic characteristics is clarified. On-vehicle test on a chassis dynamometer shows that the newly developed hydraulic engine mount has same effect on ride comfort improvement as a conventional hydraulic mount.
2010-10-05
Technical Paper
2010-01-1977
Zhang Wu, Liu Kai, Zhou Chunguo
Pulley deformation is one of the factors(the belt's deflection, power lose of hydraulic and lubrication) affect transmission efficiency of metal belt CVT. It leads to the cause of the metal belt deflection, intensifies whole-Part wear and reduces the life-span of the CVT. In this paper, the pulley deformation has been analyzed by finite element software, and the results indicate that with the increase of transmission ratio, the driver pulley deformation decreases, stress is increases after reduces for a while, and the driven pulley deformation and stress increase. These results from finite element analysis are in agreement with those from others experimental data, whereby demonstrating that the established finite element model is rational and that the analysis results are reliable.
2010-06-09
Technical Paper
2010-01-1411
Vanni Falasca, Francesca Bandera, Giorgio Irato, Ivano Giovannini, Massimo Martini, Mauro Mossino
In this project, developed together by IVECO and CRF, the goal of quantifying the perceived quality of the acoustic environment inside the truck cab was pursued. Based on considerable experience in connecting subjective response and objective acoustic data ([1], [2]), a solution was devised, by means of a statistical regression analysis connecting a very complete subjective testing survey (comparing field and laboratory tests) with a detailed investigation of psychoacoustic field measurements. Good correlation was found between field (ecological) and laboratory listening tests, so that it was possible to construct reliable perceptual models, composing both standard and custom-made psychoacoustic measurable items.
2012-11-25
Technical Paper
2012-36-0631
Guilherme Pedroto Magalhaes, Eduardo Gayer, Luiz Vercosa, Jules Slama
Brazil will soon host the two major sports events throughout the world: the Football World Cup and the Olympic Games. Therefore several ventures are in planning and some are already in implementation. The first phase of these projects is the deployment, where several activities of civil construction are developed. The activities in general are developed in consolidated urban areas, treating very often modification of an urbane important installation. Thus, in this initial phase are executed activities of demolition, cleaning, preparing the land, foundation and piling, which are considered noisy for people, causing great discomfort to the existing community around the construction site. The objective of this paper is to present some information about the noise generated by the activities of civil construction and how to manage the environmental impact sound generated by the machinery and equipment used in these activities.
2012-11-25
Technical Paper
2012-36-0632
Guilherme Zardo Selbach, Celso Cruz, Rafael Mazzorana, Gustavo Bastchen, Andre Piekarski, Rodrigo Martins, Gustavo Hindi
Health related problems in over populated areas are a major concern and as such, there are specific legislations for noise generated by transport vehicles. In diesel powered commercial vehicles, the source for noise are mainly related to rolling, transmission, aerodynamics and engine. Considering internal combustion engine, three factors can be highlighted as major noise source: combustion, mechanical and tailpipe. The tailpipe noise is considered as the noise radiated from the open terminations of intake and exhaust systems, caused by both pressure pulses propagating to the open ends of the duct systems, and by vortex shedding as the burst leaves the tailpipe (flow generated noise). In order to reduce noise generated by vehicles, it is important to investigate the gas interactions and what can be improved in exhaust line design during the product development phase.
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