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Viewing 1 to 30 of 266
2004-10-26
Technical Paper
2004-01-2717
Wei Liang, Jure Medanic, Roland Ruhl
Control system design is one of the most critical issues for implementation of intelligent vehicle systems. Wide ranged fundamental research has been undertaken in this area and the safety issues of the fully automated vehicles are clearly recognized. Study of vehicle performance constrains is essential for a good understanding of this problem. This paper discusses safety issues of heavy-duty vehicles under automatic steering control. It focuses on the analysis of the effect of tire force saturation. Vehicle handling characteristics are also analyzed to improve understanding of the truck dynamics and control tasks. A simple differential brake control is formulated to show its effect of on reducing trailer swing.
2004-10-26
Technical Paper
2004-01-2714
Katrin Strandemar, Boris Thorvald
This paper presents the ride diagram, a new way of evaluating and presenting ride comfort Furthermore, a simplified methodology is suggested to test and correlate objective measures of vehicle ride with subjective driver impressions. The ride diagram is calculated from measured cab accelerations resulting from increased levels of excitation. The basic idea is to graphically visualize how ride comfort changes with excitation. Test drivers are then asked to pair the set of tested vehicles with corresponding curves in the ride diagram. This step assures that the selected measure captures how drivers apprehend changes in vehicle ride. The suggested methodology is illustrated on trucks with different cab suspension settings. For a given test track increased vehicle speed is used to increase the excitation level. The trucks are also placed in a road simulator to enable easy variation of both excitation type and level.
2004-10-26
Technical Paper
2004-01-2697
Leonard Kuo-Liang Shih, Tien-Chou Hsu
In the past decades, the diesel engines are considered as the major power source, not only because of their high thermal efficiency, high torque output, and easy maintenance; but also due to the improved exhaust emissions reduction technology. In order to increase the thermal efficiency, the low heat rejection ceramic coating engine is one of the possible solutions for future engine manufacturing. Due to the thermal insulating effects of the ceramic material (low thermal conductivity), the cylinder charge and engine components' temperatures are substantially increased. However, the thermal impact problem and the possible high friction characteristics of the new coating material can be deadly to the engine's lifetime. Various non-ceramic and ceramic materials are tested in this research to decide their thermal insulating effects on the engine performance and their downside on the friction and thermal impact problems.
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.
2004-10-26
Technical Paper
2004-01-2658
William Wangard, Aleksandra Egelja, Hossam Metwally
A transient, 3-dimensional, continuum CFD model of soot loading and regeneration has been developed for a single channel unit in a diesel particulate filter. The detailed model is used to predict the soot loading, velocity, temperature, and species distributions in both the air channels and porous walls of the filter. The simulation is performed in two phases: loading and regeneration. In the loading phase, soot profiles are estimated for a clean filter using a steady-state simulation. In the second phase, transient regeneration is modeled using a single-step, irreversible heterogeneous mechanism is used to predict the formation of carbon monoxide and carbon dioxide products during the regeneration process, incorporating a fractionization scheme. Reaction rates are predicted via an Arrhenius rate law, but may be tempered due to diffusion-limiting conditions in the porous reaction zone. Simulations are performed with a commercial CFD package and user-defined functions.
2004-10-26
Technical Paper
2004-01-2707
Rosca Radu, Rakosi Edward, Manolache Gheorghe
The paper attempts to determine which traction model best fits with experimental data for a romanian lugged tractor tire. Different models for predicting net traction and traction efficiency for off-road conditions were considered. These models assume different tire-ground pressure distributions (constant, parabolic) over the undertread area and different contact patch length calculations. Experiments were conducted and the results were compared to the theoretical data. Two of the models are the best fit with the experimental data; both models assumed a parabolic pressure distribution over the undertread.
2004-11-16
Technical Paper
2004-01-3437
Paulo Pedro Kenedi, Leydervan de Souza Xavier, Ricardo A. Amar de Aguiar, Rafael de Oliveira Sampaio, Thiago Fontes Carvalho de Queiroz
In order to resist impact loadings that usually occurs in an off-road circuit an integrated approach of mechanical design is developed to obtain an optimized vehicle suspension. Efforts were made to model a front suspension, type double A of an off-road vehicle Mini-Baja. The focus was stressed in the transmissibility of mechanical forces through front suspension. A simple analytic model was done to esteem the reactions generated at points of linkage of suspension and structure of Mini-Baja, during a transient impact load. Numerical simulation softwares were also used to visualize dynamic behavior of different front suspension configurations. Finally experimental test was done with data acquisition system, with the use of load cells, to generate a reference data to compare analytic and numerical models.
1999-11-15
Technical Paper
1999-01-3757
Konghui Guo, Qing Liu
One of the most essential factors causing automobile and aircraft shimmy is energy import from road to tires due to tire hysteresis characteristic. The magnitudes and direction of the energy import are close to frequency responses of tire cornering properties (TCP), which can be calculated directly according to the presented non-steady state TCP theoretical model. Selfexcited shimmy is the main type of wheel shimmy and behaves as negative equivalent damping characteristic of the tire-road vibration subsystem. The values of energy import or equivalent damping determine the tendency of wheel shimmy. Tire structural parameters have certain effects on frequency response of TCP and thereby result in influences on wheel shimmy. Based on the tire model, some valid ways to decrease shimmy tendency are concluded through proper variations of carcass stiffness, tire-width, kingpin caster, tire pneumatic trail, tire cornering stiffness and so on.
2004-11-16
Technical Paper
2004-01-3257
Ivan Roger Scansani Gregori
1. SUMMARY There is a large variation in the results of the durability of friction facings in field applications and in most cases there is very little information about the conditions in which the vehicle operated and therefore it was decided to developed a test procedure capable of containing all the different conditions of a vehicle. For this works statistical applications such as DOE (Experimental Design for Experiment) were used to help in planning and to obtain of equations of the tests results and Weibull curves for statistical analysis and comparison of failure mode. By this mean, it was possible to determine a correlation of the results on wear between the bench test and mileage covered on vehicle up to total wear. Therefore it is new possible to estimate the durability of friction facing on vehicles based on bench tests and also obtain knowledge about the behave of the material relative to energy and working temperature.
2004-10-26
Technical Paper
2004-01-2624
Manuel J. Fabela-Gallegos, David Vazquez-Vega
In this paper, the importance of determining the lateral acceleration to characterize terrestrial vehicle behavior and its performance is addressed. Also, the technical difficulties to measure such acceleration and its dependency with vehicle roll angle are described. In the analysis of the motion of the vehicle's center of gravity (CG) and regarding to transversal acceleration components, the acceleration of gravity is taken into account to determine the roll angle, the lateral acceleration and the behavior of vertical acceleration component. As a result, and based upon the principles of operation of accelerometers, a scheme for a simple instrumentation to estimate the roll angle and lateral acceleration in an experimental assessment, is suggested as well.
2015-09-29
Technical Paper
2015-01-2851
Aleksandar Egelja, Darren Allan Blum, Kalpesh N. Patel
Abstract Many off-highway machines, including hydraulic excavators, perform cyclical motion in their everyday activities where there is significant acceleration, deceleration, load lifting and hydraulic implement lowering. During that time in conventional off-highway machinery, most of the potential or kinetic energy is dissipated as heat instead of being captured and reused. When these opportunities are well understood and consequently machine systems are designed and integrated properly, fuel efficiency improvements could reach double digit values. It should be noted that the mentioned machine efficiency improvements will still vary depending on the machine size, its application and the characteristics of machine system(s) being applied. An approach for excavator energy flow analysis, coupled with rapid machine control design changes directed to minimization of energy losses is discussed.
2016-04-05
Journal Article
2016-01-0984
Venkatraman Mahadevan, Suresh Iyer, David Klinikowski
Abstract This paper proposes a method to recover species concentrations at the tail pipe exit of heavy-duty vehicles during chassis dynamometer tests, and investigates its effect in the calculation of emissions from their raw exhaust streams. It was found that the method shown in this paper recovered the sharp peaks of the gas species. The effect on calculations was significant, as time-variant raw exhaust flow rate and emissions concentrations data are acquired continuously during a test (at 10 Hz), and their product is integrated during calculations. The response of the analyzer is delayed due to the time taken for transport of the sample gases from the probe tip to the analyzer, and deformed due to mixing and diffusion during this transport. This ‘convolution’ of the concentration data stream introduces an error in the final result, calculated in g/mile.
2016-04-05
Technical Paper
2016-01-0469
Hyunkoo Kang, Wooyong Jung, Choon Lee
Abstract This paper presents payload estimation based on experimental friction coefficients identification. To estimate exact payload mass, dynamic mathematical model such as actuator dynamics and front linkage dynamics is derived by using Newton-Euler method. From the dynamic equation, nonlinear terms are analyzed and transformed. And a friction model is derived from the experiments with various conditions which have three states; boom joint angle, head and rod chamber pressures. It can identify friction coefficients and compensate friction forces. In addition, the accuracy of payload estimation system is verified through the field test.
2016-04-05
Technical Paper
2016-01-1329
Fulin Wei, Yanhua Shen, Tao Xu
Abstract Off-road dump truck body is exposed to abrasive wear during handling of granular materials. The wear rate of body of dump truck has direct influence on maintenance and replacement during its service process. In this paper the discrete element method (DEM) is used to simulate the granular materials of dump truck. The wear of body floor during one dumping process can be achieved by cosimulation of FEM-DEM. The wear depth variation of body has the stochastic characteristic which can be modeled by Geometric Brownian Motion (GBM). The two parameters in the stochastic differential equation, drift coefficient and diffusion coefficient, can be estimated by the wear depth measuring data. It is possible to quantitatively predict the wear evolution of every grid point of the body floor by solving this stochastic differential equation. The simulation result of the wear model is helpful to optimize design of off-road dump truck body.
2005-05-11
Technical Paper
2005-01-2153
Shuhong Xu, Nigel N. Clark, Mridul Gautam, W. Scott Wayne
The Tapered Element Oscillating Microbalance (TEOM) measures captured particle mass continuously on a small filter held on an oscillating element. In addition to traditional filter-based particulate matter (PM) measurement, a TEOM was used to characterize PM from the dilute exhaust of trucks examined in two phases (Phase 1.5 and Phase 2) of the Coordinating Research Council (CRC) Heavy-Duty Vehicle Emissions Inventory Project E-55/E-59. Test schedules employed were the Heavy Heavy-Duty Diesel Truck (HHDDT) test schedule that consists of four modes (Idle, Creep, Transient and Cruise), the HHDDT Short (HHDDT_S) which represents high-speed freeway operation, and the Heavy-Duty Urban Dynamometer Driving Schedule (UDDS). TEOM results were on average 6% lower than those from traditional particulate filter weighing. Data (in units of g/cycle) were examined by plotting cycle-averaged TEOM mass against filter mass. Regression (R2) values for these plots were from 0.88 to 0.99.
1990-10-01
Technical Paper
902281
Bang Jie Luo, Zhang Tiezhu, Shurong Wu, Dejie Xien
: Starting from the real vehicle working conditions and taking that engine works at the optimum economic line as a foundation, this paper gives the power transmissive principle of hybrid vehicle with energy storage flywheel working in process of accelerating, uniformly running and braking, derives the relationship of the ratio and time in continuously - variable transmission(CVT) under working conditions of adjusting engine load, recovering and releasing energy etc., and provides the theoretic foundation for transmission system of flywheel energy storage vehicle to realize optimum economic control.
1990-10-01
Technical Paper
902283
S. Kiriczi, R. Kashani
Abstract Filtering the road unevenness, i.e. comfortable ride for passengers, and vibration and shock isolation for freight, is one of the main thrusts behind the development of active and semi-active suspensions. For control of these systems, a variety of different schemes, mainly from the linear stochastic control area, have been proposed by researchers: and 1/4-car active and semi-active suspension models are used to simulate these schemes. Besides the main input an exogenous input is also considered, namely a velocity disturbance originating from the road unevenness. In most of the literature in this area, this disturbance is considered as white noise, which it hardly is. This a-priori statistical description of the disturbances, is necessary for using stochastic control techniques. In this paper, a comparison of some of these control schemes is performed.
1992-04-01
Technical Paper
920929
E. C. Fitch, I. T. Hong, R. K. Tessmann
Separation efficiency, contaminant capacity and operating power consumption are the three major factors in determining the performance of any separator. For an ideal separator, all unwanted material should be removed from the process fluid. In addition, the ideal separator must hold an infinite amount of separated contaminant and consume no power. Unfortunately, such an ideal separator is impossible to attain under the current laws of physics. However, the technology presented here represents a major step closer to these objectives. This paper introduces a new concept, orbital separation, for achieving high performance gas, liquid and solid separation. Orbital separation has nearly unlimited contaminant capacity and requires only a fraction of the input power required by other separation techniques. In this paper, the general principles of filtration and separation mechanics are reviewed. The orbital separation concepts are discussed and illustrated.
1992-09-01
Technical Paper
921686
Max P. Gassman
Analysis of a fluid power system with the use of a mathematical model can provide much useful information for good design and safety of a machine. Analysis of a system may cover flow distribution, component operation, or a combination of both. A method is described in this paper, that allows inclusion of all aspects of a fluid system in a single mathematical model. The method may be used to predict circuit flow division simultaneously with component behavior.
1992-09-01
Technical Paper
921659
Petter Krus, Jan-Ove Palmberg
Mobile hydraulic equipment are today operated manually to a very large extent. There are, however, some applications where substantial benefits would be obtaind if some kind of feedback and more sophisticated control was used. One such application is the control of a crane. Usually the operator controlls the flow to each of the pistons so that the crane tip is moved in the desired direction (Fig. 1). Since many mobile hydraulic valves packages have electronic input and there exists built in position transducers for the pistons, it seems to be rather straightforward to introduce vector control of the crane tip directly. That is, the operator commands controlls the direction and speed of the crane tip. Here, a control algorithm is described that allows the use of mobile electrohydraulic proportional valves while still having accurate vector control of the crane tip.
1992-09-01
Technical Paper
921669
Sarim N. Al-Zubaidy
The paper describes a general method, based on a simplified flow model, for the analysis of compressible, unseparated and non-uniform flows in diffusing ducts of arbitrary geometry and inlet flow conditions. The method has been tested against available detailed experimental data of conical and straight rectangular diffusers, and was able to predict (with an acceptable degree of accuracy) the likely performance of diffusing flows at various values of inlet Mach numbers.
1992-09-01
Technical Paper
921728
Arcadii Z. Grinshpan
Practical use of mathematical models, that describe complex physical processes, connected with heat and mass transfer (the working process of diesel engine in particular), often runs into considerable difficulties. These difficulties are engendered by the general character of the problem, the large amount of characteristics considered, the complexity of their interdependence and as a sequence the cumbersomeness and inconvenience the mathematical apparatus itself. To overcome these obstacles it is helpful in some cases to introduce some auxiliary parameters, and in other cases - to find a successful functional parametric representation of the characteristics investigated. Both above mentioned approaches are components of the parameterization method and play a significant role in solving technological problems by means of mathematical modeling. Use of parameterization is shown by three examples.
1992-09-01
Technical Paper
921731
S. Aly, Sarim Al-Zubaidy
The work presented in this paper is concerned with the development of a performance prediction method for centrifugal pumps. Many formulae that have been used to predict pumps likely performance are based on expressions developed originally for centrifugal compressors, these were modified for pumps by removing the compressibility flow effects. Additional pump loss correlations were re-written and directly applied to typical pump geometries. Experimental performance measurements of seven centrifugal rotors have been compared with analytical predictions using the proposed method, the results were encouraging.
1992-09-01
Technical Paper
921732
Sarim Al-Zubaidy, Mahdi Dahgan
The paper proposes a performance prediction method at design and off design values of mass rate and rotational speed for a low pressure ratio (2.2:1) centrifugal compressor capable of rotating at speeds up to 90000 r.p.m. The procedure employed consists of combining selected losses obtained from semi-empirical equations to construct an overall picture of efficiency of the compression process. The estimated performance of a radial centrifugal compressor with splitter blades was compared with experimental results covering wide range of the performance map, the achieved level of agreement was approximately within 4% from measurements. It should be mentioned however that the proposed method does not describe the internal aerodynamic effects occuring, it does however isolate some important variables and then relate them to the total pressure loss across the stage.
1992-09-01
Technical Paper
921747
Yan Min, Sun Xinxue, Wu Dongmei
: In the recent years, the design on the link-mechanism of working device in a loader is gradually being prefected, but the design on the link-mechanism of boom-cylinder is seam to be still at the cut and try level. In order to further improve the design method of boom cylinder, in this paper, using a concept of “dfficiency” or “advantage” and a method combining the theoritical analysis with the computer computation, we make an attempt at analyzing and discussing this problem. And finally we obtain some conclusions for increasing the design quality of the link-mechanism.
1992-04-01
Technical Paper
920916
V. Rajarajan, T. C. Tecco
The application of computers to design analysis has improved product knowledge. This paper discusses two applications of computer-aided design analysis that improves the productivity of engineers and analysts. The first application discussed is that of structural boundary elements. In the last few decades domain discretization techniques such as the finite element method have been used extensively for design analysis. Surface discretization techniques such as the boundary element method offer significant advantages over the finite element method in terms of modelling effort required and relative accuracy achieved for a given mesh density. The second application is the solution of inverse thermal problems. This technique aids in the determination of temperature distribution of a component, given some experimentally obtained temperature data.
1994-11-01
Technical Paper
942304
Faisal Oueslati, Seshadri Sankar
A covariance analysis technique is proposed to derive the optimal suspension parameters of an articulated freight vehicle. A performance criteria comprising vehicle ride response, suspension deflections and tire deflections related to dynamic wheel loads, is formulated for the 9 degrees-of-freedom (DOF) in-plane model of the vehicle. The range of suspension parameters to achieve four different design requirements is identified and a parametric study is performed to make initial parameter selection using the covariance analysis. The optimal suspension parameters are then identified from the results of the study. The study concludes that the proposed technique can yield the optimal solution in a convenient and highly efficient manner.
1994-11-01
Technical Paper
942303
Junghsen Lieh
This paper presents the application of a multibody formulation program to generating equations of motion for commercial vehicles. The formulation procedure adopts the separated-form virtual work principle. Equations are expanded using generalized coordinate partitioning through a Jacobian matrix expansion. The inertia force vector is separated into nonlinear, linear and time-dependent terms, and the generalized force vector is derived from virtual energies. Friction forces are included in the formulation. Nonlinear and linearized models are provided in a symbolic FORTRAN form allowing the control design be implemented with second-order or first-order equations. A fourth-fifth order Runge-Kutta-Fehlberg's algorithm with self-adjustable step sizes is utilized to numerically integrate the reduced systems. An example, a six-axle tractor-semitrailer model is demonstrated.
1994-03-01
Technical Paper
940247
S. Thangjitham, N. E. Dowling, C. Leser
Abstract A concise method for modeling nonstationary fatigue loading histories is presented. The mininum number of model parameters is achieved by fitting the variations in mean and variance by a truncated Fourier series. An autoregressive moving average (ARMA) model is used to describe the stationary component. Justification of the method is made by comparing fatigue relevant parameters obtained when subjected to the original and reconstructed histories. In spite of a relatively small number of parameters required, the model is shown to give good results that fall within the bounds predicted by the orginal history.
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