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Viewing 1 to 30 of 874
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
Journal Article
2013-01-2009
Pranab Saha, James Haylett, Ranjit K. Roy
This paper discusses a design of experiments (DOE) analysis that was performed to understand relevant factors that influence the acoustic performance of a sound package part used in the commercial vehicle industry for the floor mat application. The acoustic performance of the sound package part which is a double wall system and constructed of a barrier and cellular decoupler material is expressed in terms of sound transmission loss (STL). An experiment was designed using the Taguchi DOE technique with three factors and three levels to acquire the STL data and is discussed in the paper. The results of the DOE analysis and the confidence in the model are discussed as well as the benefits of predicting expected STL performances are mentioned in the paper.
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.
2013-05-13
Technical Paper
2013-01-2010
Jiantie Zhen, Aaron Brames, Tyler Williams, Clinton Metzger
NVH is gaining importance in the quality perception of off-highway machine performance and operator comfort. Booming noise, a low frequency NVH phenomenon, can be a significant sound issue in an off-highway machine. In order to increase operator comfort by decreasing the noise levels and noise annoyance, a tuned mass damper (TMD) was added to the resonating panel to suppress the booming. Operational deflection shapes (ODS) and experimental modal analysis (EMA) were performed to identify the resonating panels, a damper was tuned in the lab and on the machine to the specific frequency, machine operational tests were carried out to verify the effectiveness of the damper to deal with booming noise.
2013-05-13
Technical Paper
2013-01-2011
Mahender Singh
Refuse Trucks are used to pick up garbage from houses. These trucks have huge robotic arms connected to the frame which are operated by hydraulic mechanism operated by the driver sitting inside the cab of the truck. The operator of the truck controls the robotic arm using a lever. Once the truck is positioned aside the garbage can, the operator moves the robotic arm outwards, grabs hold of the garbage can, picks up the garbage can and dumps the garbage into the truck. During this operation, the frame articulates and moves due to the frame suspension causing the cab to move along with the frame. This operation is performed about 1000 times a day, 5days a week for 12 years which could result in some amount of damage to the cab over its life. Since the time rate of application of the forces during the Automatic Side Loading operation is small compared to the lowest flexible mode of the cab, modal amplification is considered unlikely.
2013-11-27
Technical Paper
2013-01-2757
Sreegururaj Jayachander, Prasanna Vasudevan
Technology is one of the key determinants of the outcome in today's wars. Many targeting systems today use infra-red imaging as a means of acquiring targets when ambient light is insufficient for optical systems. Reducing thermal signatures offers an obvious tactical advantage in such a scenario. One way to reduce thermal emission of combat vehicles is to adopt highly efficient electrical power trains instead of internal combustion engines that tend to reject a sizeable amount of the input energy as heat. The tractor is one of the most versatile vehicles that are used in the theatre of combat for various operations such as haulage, clearing terrain, deploying bridges, digging trenches etc due to its excellent abilities in handling difficult terrain. A tractor powered by an all-electric power train was developed for civilian applications. The traction characteristics are identical to that of a conventional diesel powered tractor of comparable size.
2013-09-08
Journal Article
2013-24-0177
Philipp Vögelin, Peter Obrecht, Konstantinos Boulouchos
Future engine emission legislation regulates soot from Diesel engines strictly and requires improvements in engine calibration, fast response sensor equipment and exhaust gas aftertreatment systems. The in-cylinder phenomena of soot formation and oxidation can be analysed using a pyrometer with optical access to the combustion chamber. The pyrometer collects the radiation of soot particles during diffusion combustion, and allows the calculation of soot temperature and a proportional value for the in-cylinder soot density (KL). A four-cylinder heavy-duty Diesel engine was equipped in all cylinders with prototype pyrometers and state of the art pressure transducers. The cylinder specific data was recorded crank angle-resolved for a set of steady-state and transient operating conditions, as well as exhaust gas recirculation (EGR) addition and over a wide range of soot emissions.
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
2013-01-2381
Shannon K. Sweeney
This paper presents a simple method of estimating steady-state diesel engine disturbance amplitudes that can be used in rigid-body, low frequency vibration modeling to predict the performance of an engine's isolation suspension and its components. The internal disturbances occurring at each cylinder and crank throw are determined and combined to provide the net disturbances for several common four-stroke diesel engine configurations. The method utilizes a simplified Fourier decomposition of diesel combustion and the predominant inertia disturbances from within the engine. With a few pieces of information from the engine maker, actual disturbance amplitudes and phases can be estimated. Conditions and simplifying assumptions are discussed. The estimated disturbance amplitudes can also be used in torsional vibration modeling of the drivetrain.
2013-09-24
Technical Paper
2013-01-2380
Anandan Sivakumar, Sachin Wagh, G. Raghavendra, Chaitanya Govind Kulkarni, Hemant Malekar
Success of the vehicle in the market depends on comfort provided while usage, which also includes noise, vibration and harshness (NVH). In order to achieve comfort level, the NVH levels have to be as low as possible. Powertrain is the main source of NVH, in which internal combustion engine consists of crank shaft and balancer shaft. Crank shaft gear is connected and driven by crank shaft and balanced by integral eccentric mass coupled with gear. Balancer shaft is used for additional balancing of rotating masses. Pair of crank shaft and balancer shaft gears generates noise and vibration when unbalance in the system and backlash in the gears increase while usage. The practice of interposing a vibration isolator on the surface of gear has been so far resorted for preventing transmission of vibration, therefore reduction in noise. In the work presented, balancer gear was made with sandwich design to reduce noise. Sandwich design comprises of Inner hub and outer ring with lug projections.
2013-09-24
Technical Paper
2013-01-2351
Vijay Antony John Britto, Ekambaram Loganathan, Sivasankaran Sadasivam, Kalyankumar Hatti, Sai Sankaranarayana
Driver fatigue is one among the important factors for accidents, causing loss of precious life and property. Apart from long driving hours, driver fatigue can be due to poor ride quality, cabin noise, high vibration levels and poor ergonomics. In last few years, there has been enough emphasis to improve the noise and vibration comfort of commercial vehicles, which is governed by vibration levels at tactile points such as steering wheel, gear lever, pedal and seat. Steering wheel vibration is an important element which driver uses to express about the vehicle vibration quality. Design of steering system is driven by ergonomics, packaging, durability, safety, vibration & ride and handling requirements. This paper discusses about methodology of steering assembly development for Noise Vibration and Harshness (NVH) performance of commercial vehicle.
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
2013-26-0093
Vilas Gorakh Umbare
The design and analysis plays a major role for determining the root cause for the problem. Once the problem and its root cause were well defined, the solution for addressing the problem would be made clear. The engine excitation frequency and the chassis natural frequency were coming closer and it leads chassis to resonate. The resonance increases vibration levels at the Tractor footrest which was reducing comfort level of the operator. The vibration reduction methodologies like stiffening the structure, isolating the source from excitation and dampening techniques were studied to reduce vibration levels at footrest. The benchmarking evaluation was done with selected tractor models qualitatively to assess the difference in vibration level perception for customers. The test methodology and data acquisition methodology was formulated and used for better analysis and discussions.
2013-01-09
Technical Paper
2013-26-0097
Sachin Pawar, Murali Bodla, Rajesh Bhangale, Mansinh Kumbhar
Whole Body Vibration (WBV) of tractors was measured on different surfaces in real world usage pattern of Indian customers on tractors of various capacities. Vibration levels were measured at the interface of the seat and the operator, on the seat base/floor and on the head. The mean weighted Root Mean Square (RMS) values along the different axes, the vector sum of weighted RMS values along the three orthogonal axes, the crest factor, Vibration Dose Value (VDV) and 8 h exposure levels were calculated according to ISO 2631-1. In addition to the above parameters, the transmissibility between the seat base and the seat interface (SEAT) and between the seat interface and the operator head (TR) were also calculated. Finally, these parameters were correlated with the subjective feel of customers which was captured through suitable questionnaires. It is observed that the Indian tractor operators are exposed to WBV that exceeds the cautionary boundaries set in place by the ISO 2631-1.
2013-01-09
Technical Paper
2013-26-0100
J. Sai Prasad, N. Chollangi Damodar, T. Sudhakara Naidu
The acceptable noise and vibration performance is one of the most important requirements in a passenger bus as it is intended for widest spectrum of passengers covering all age groups. Gear rattle, being one of the critical factors for NVH and durability, plays a vital role in passenger comfort inside vehicle. The phenomenon of gear rattle happens due to irregularity in engine torque, causing impacts between the teeth of unloaded gear pairs of a gearbox which produce vibrations giving rise to this unacceptable acoustic response. In depth assessment of the dynamic behavior of systems and related components required to eliminate gear rattle. During normal running conditions, abnormal in-cab noise was perceived in a bus. Initial subjective evaluation revealed that the intensity was high during acceleration and deceleration. Objective measurements and analysis of the in-cab noise and vibration measurements had indicated that the noise is mainly due to gear rattling.
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.
2013-01-09
Technical Paper
2013-26-0104
Rohit Ravindran, Vijay Antony, Saisankaranarayana K, Kalyan S. Hatti
In recent years NVH has gained a lot of importance in the commercial vehicle industry as it contributes significantly towards user comfort and also towards the quality perception associated with a vehicle. The in-cabin noise of vehicles is critical towards the comfort and usability for the end user and the sound package installed on the vehicle plays a vital role in determining the levels associated with this attribute, especially the high frequency content. The paper discusses a methodology for optimizing the sound package for performance, cost and mass, for a truck. The approach uses a Statistical Energy Analysis (SEA) based optimization. A virtual SEA model is developed, which is correlated with actual test data. After establishing the correlation, an optimization study is carried out to identify the effectiveness of different materials and material combinations towards in-cabin noise.
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.
2011-09-13
Technical Paper
2011-01-2238
Shannon K. Sweeney
This work provides a theoretical analysis of the natural and forced lateral vibration in a driveline having a flexible coupling and universal joints. The analysis is specific to the front driveline common in many off-highway vehicles which usually consists of a flexible coupling at the engine flywheel, the driveshaft, and one or two universal joints. A torsionally flexible coupling is often needed in a front driveline to suppress torsional vibration. The problem is that most torsionally flexible couplings are also inherently flexible in their radial and cocking directions. These additional directions of flexibility, compounded by the presence of universal joints, can result in unexpectedly low lateral natural frequencies of the driveline. With a few axial dimensions, mass properties of the driveline, and stiffness properties of the flexible coupling, this work provides simple, closed-form calculations for the lowest lateral natural frequencies.
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).
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