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Viewing 1 to 30 of 280
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.
2013-09-24
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
2013-01-2351
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.
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.
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
2011-01-1670
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).
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.
2011-10-04
Technical Paper
2011-36-0269
Everton Corte, Maria Lúcia Machado Duarte, Henrique Schaeffer Batista, Gabriel Silva
This paper discusses the importance of vibration transmitted from the ground to the driver from the perspective of human whole-body vibration (WBV). The scope of analysis is to compare the main vehicle frequencies with those important from the human vibration health and comfort point of view. That was performed by mapping the vibration transmissibility present in different sub sections of the vehicle. The first is the transmissibility between the axles and the chassis rail, the following between the chassis rail and the cabin. The last would be between the cabin and the drivers' seat, although that was not possible from the acquisition point of view. The vehicles measured have mechanical suspension and elastomeric cabin coupling. It is known that all suspension systems in vehicle are highly nonlinear, although here linear dynamic analysis methods were used.
2012-09-24
Technical Paper
2012-01-1971
Yan Tan, Zeguang Tao, Steve Gravante
Good performance of fuel system is critical for fuel efficiency, combustion process, emissions, start ability, acceleration and combustion noise. The fuel system design is a complicated process. Simulation tools are playing an important role in virtual design. They are used to evaluate performance, optimize the design, and provide understanding for performance or durability related problem. This paper illustrates how a 1D system simulation tool is utilized to investigate an observed failure of a high pressure hose. The simulation identifies the dominant modes in the fuel system and determines the engine speed at which the fuel system mode is excited. At various engine speeds, the simulation investigates the magnitude of pressure pulsation in the high pressure hose of the fuel system. Finally, the 1D simulation provides the design optimization approach to suppress the oil pressure pulsation and reduce the structure vibration.
2012-09-24
Technical Paper
2012-01-2008
Mohsen Bayani Khaknejad, Arash Keshavarz
In this research the main focus is on reducing the transmitted engine vibration through exhaust line to the passenger cabin in a light commercial vehicle. The main approach is firstly to locate the mountings of the exhaust system based on the results of the modal analysis. Afterwards, the stiffness of the rubber hangers is optimised to minimize the measured vibration in the driver seat rail position. The optimisation approaches are executed considering the design of experiments method. To achieve this, the partial BIW model of the reference vehicle and the powertrain system is generated in FE software. The FE model of the exhaust system is validated by experimental results. In order to define the optimum stiffness for the exhaust rubber hangers, design of experiments method is used. The main candidate parameters for DOE analysis are exhaust rubber hangers in the front floor region in addition to the exhaust flexible joint stiffness.
2012-09-24
Technical Paper
2012-01-2011
Han Zhang, Xuexun Guo, Zhigang Fang, Guanneng Xu
The basic principle of wavelet transform is presented and the method of wavelet theory is used in vibration signal analysis of vehicle in this paper. The vibration signals which generated in the locations such as cab floor, engine, transmission, band spring and frame under the usual work condition are measured by the vibration test system. The vibration signals are decomposed with the principle of wavelet decomposition at level six, and eigenvectors of signal energy are gained. According to the correlation coefficient of eigenvectors of signal energy distribution, two signals correlativity is determined. It could be an effective method that identificate the main vibration source.
2015-05-13
Technical Paper
2015-36-0004
Patric Daniel Neis, Ney Francisco Ferreira, Luciano Tedesco Matoso, Diego Masotti, Jean Carlos Poletto
Abstract The present paper addresses an investigation about the definition of a parameter for quantifying the creep-groan propensity in brake pads. Creep-groan is a self-excited vibration caused by stick-slip phenomenon [1, 2, 3]. For the definition of the creep-groan propensity parameter, extensive experimental work was performed on a laboratory-scale tribometer. The experiments are divided in two main parts: (i) study of correlation between accelerometer signal with physical and operating parameters. (ii) validation of the chosen parameter, which was based on stick-slip tests performed with three different materials, one low-metallic (low-met) and two non-asbestos organic (NAO 1 and 2). From the first study, it was found that both the slip power and mean torque multiplied by torque variation showed a slightly higher correlation with the acceleration signal.
2015-01-14
Technical Paper
2015-26-0127
Gaurav Paliwal, Naveen Sukumar, Umashanker Gupta, Saurav Roy, Hemantkumar Rathi
Abstract The main emphasis for a commercial vehicle design which was focused on fuel-economy and durability does not fulfill the increasing customer expectations anymore. Commercial vehicle designers need to focus on other vehicle aspects such as steering, ride comfort, NVH, braking, ergonomics and aesthetics in order to provide car like perception to truck, bus drivers and passengers during long distance drives. Powertrain mounting system must perform many functions. First and foremost, the mounting system must maintain & control the overall motion of the powertrain, to restrict its envelope reasonably, thereby avoiding damage to any vehicle component from the potential impact. This requires the mount to be stiff. Second the mount must provide good vibration isolation to have a comfortable ride to the vehicle occupant. This requires the mount to be soft.
2013-05-13
Technical Paper
2013-01-1928
Ganesh Vijaykumar Kinagi, Suresh Wadkar, Dnyanesh Sonawane
Mathematical modeling of any system plays an important role in research and engineering applications. Development of hydropneumatic suspension system requires a complete understanding of physical phenomenon and generating governing equations of the same. In this paper, mathematical model of a typical hydropneumatic suspension system is made and simulation of such a complex multi domain system is programmed in MATLAB Simulink software. Vibration isolation potential of hydropneumatic suspension system is investigated through mathematical modeling, incorporating nonlinearity due to polytropic nature of gas spring.
2014-09-30
Technical Paper
2014-36-0144
Luiz Bellatini, Demetrio Vettorazzo, Carlos Barbosa, Paulo Falcone, Carlos Sena, Josevaldo Fernandes
Abstract The purpose of this paper is to provide an overview about rowing clunk on RWD MT transmissions for pick-up trucks through means of sound pressure, case acceleration and torsional vibration. Intended to identify the proper synchronizer design features necessary for its prevention. This paper will introduce the rowing clunk phenomena and present the driving maneuvers executed to reproduce the noise. The process of analysis and the phenomena composition based on simulations results, noise measurements and vibration analysis. The objective is to share with Product Engineering community an approach for Rowing Clunk Noise mitigation on Pick-up Trucks.
2014-11-04
Technical Paper
2014-36-0793
Elton J. Zanol, Letícia Fleck Fadel Miguel, Tiago Becker
Abstract Bus drivers are daily exposed to whole-body vibrations (WBV) submitted to risks for develop health problems related to these conditions. Numerous studies focused to quantify and identify the risks that drivers are exposed have been developed in recent years. Many factors influence the transmission of vibration to the body. Road type may be an important factor in determining the WBV exposure a bus driver receives. In urban areas, common types of routes include several road surfaces like: smooth highway, older rough freeway, pavement, bumpy, speed humps, and others. The purpose of this study was to determine whether different kinds of road surfaces, found in urban routes, cause different WBV responses, and determine the influence for each road type in daily exposure to WBV according the standard ISO 2631-1 (1997).
2016-04-05
Technical Paper
2016-01-0474
Shukai Yang, Bingwu Lu, Zuokui Sun, Yingjie Liu, Hangsheng Hou
Abstract A low frequency vibration issue around 3.2 Hz occurs during a commercial heavy truck program development process, and it is linked to extremely uncomfortable driving and riding experiences. This work focuses on an analytical effort to resolve the issue by first building a full vehicle MBS (multi-body-system) model, and then carrying out vibration response analyses. The model validation is performed by using full vehicle testing in terms of structural modes and frequency response characteristics. In order to resolve the issue which is excited by tire non-uniformity, the influence of the cab suspension, frame modes, front leaf spring system and rear tandem suspension is analyzed. The root cause of the issue is found to be the poor isolation of the rear tandem suspension system. The analytical optimization effort establishes the resolution measure for the issue.
2016-04-05
Technical Paper
2016-01-0440
Li Jie, Wang Wenzhu, Gao Xiong, Zhang Zhenwei
Abstract The ride comfort of heavy trucks is related to many factors, which include vehicle operating scenarios and vehicle structure parameters. An investigation of the influence of different factors on the ride comfort of heavy trucks was conducted. Based on the elastic theory of a uniform Euler-Bernoulli beam with both ends free, a 6 degree of freedom (DOF) half rigid-elastic vibration model of the vertical dynamic response was developed. The rigid-elastic model is more suitable to describe the actual movement of heavy trucks. The DOFs include vertical displacements of the body and each of two axles, the pitch displacement of the body, and the first and second order bending displacements of the body. The root mean square (RMS) values of body accelerations, dynamic deflections and relative dynamic loads form the evaluation index. Based on the rigid-elastic model, the influence of different factors on the ride comfort of heavy trucks is analyzed in the frequency domain.
2015-09-29
Technical Paper
2015-01-2871
Mounika Katragadda, Kalyan Deepak Kolla, Venkata Suresh Yaparala
Abstract In the automotive industry many components face fatigue failure due to prolonged vibrations. This is commonly known as Vibration Induced Fatigue (VIF). There are two approaches to evaluate this; time & frequency domain. A straight forward and widely used method is the rainflow counting technique in the time domain. This counting algorithm is readily available and, apart from the time history, it needs only one variable input (the number of stress ranges). In case of high cycle fatigue, longer time histories are required for a statistically representative fatigue estimate, which makes the time domain approach consume large amounts of time and resources. This shifts our interest towards frequency domain methods. In the frequency domain, Dirlik's method is proven to be robust and gives closer results to the time domain.
2016-09-27
Technical Paper
2016-01-8116
Mrudula Uday Orpe, Monika Ivantysynova
Abstract Mobile Earth Moving Machinery like Skid-steer loaders have tight turning radius in limited spaces due to a short wheelbase which prevents the use of suspensions in these vehicles. The absence of a suspension system exposes the vehicle to ground vibrations of high magnitude and low frequency. Vibrations reduce operator comfort, productivity and life of components. Along with vibrations, the machine productivity is also hampered by material spillage which is caused by the tilting of the bucket due to the extension of the boom. The first part of the paper focuses on vibration damping. The chassis’ vibrations are reduced by the use of an active suspension element which is the hydraulic boom cylinder which is equivalent to a spring-damper. With this objective, a linear model for the skid steer loader is developed and a state feedback control law is implemented.
2016-09-27
Technical Paper
2016-01-8101
Yoshimune Mori, Akifumi Yoshimura, Nobutaka Tsujiuchi, Akihito Ito, Atsushi Fujimoto, Zenzo Yamaguchi, Koichi Honke
Abstract In a typical mechanical product such as an automobile or construction machinery, it is important to identify deformation modes, for which experiments and analyses can result in significant improvements. It is also important to consider how to improve the structure with high rigidity by using a technique such as the strain energy method in conventional design and development. However, the abovementioned method often generates conflicting results with regard to weight saving and cost reduction of development requirements. Transfer path analysis (TPA) using the finite element method (FEM) is an effective way to reduce noise and vibration in the automobile with respect to these issues. TPA can reveal the transfer path from the input to the response of the output point and the contribution of the path, and to efficiently consider improved responses.
2016-05-11
Technical Paper
2016-36-0067
Gustavo de Godoy José, Mauro Rebelatto, Rui Gustavo Lippert Schwanke, Telmo Roberto Strohaecker
Abstract This paper presents several tests carried out on a truck trailer on different types of pavement and load condition, using proving ground tracks and facilities, the instrumentation details, data analysis and validation. Through an extensive analysis of Brazilian goods road transport, a load vehicle combination and a list of test pavements were chosen as off-road pavement, highway pavement, pot holes, washboard, cobblestones and Belgian blocks. Accelerometers were installed throughout the truck trailer chassis longitudinal length in order to obtain the acceleration levels and vibration frequencies on the truck trailer sprung mass. Aiming to evaluate the base excitation imposed to parts mounted to the truck trailers chassis, according to their mounting position, data processing method and cutoff frequency definition strategies were defined.
2016-09-27
Technical Paper
2016-01-8121
Riccardo Bianchi, Addison Alexander, Andrea Vacca
Abstract Typically, earthmoving machines do not have wheel suspensions. This lack of components often causes uncomfortable driving, and in some cases reduces machine productivity and safety. Several solutions to this problem have been proposed in the last decades, and particularly successful is the passive solution based on the introduction of accumulators in the hydraulic circuit connecting the machine boom. The extra capacitance effect created by the accumulator causes a magnification of the boom oscillations, in such a way that these oscillations counter-react the machine oscillation caused by the driving on uneven ground. This principle of counter-reacting machine oscillations through the boom motion can be achieved also with electro-hydraulic solutions, properly actuating the flow supply to the boom actuators on the basis of a feedback sensors and a proper control strategy.
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