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Technical Paper

Design and implementation of an automatic system for testbenches with remote supervision.

1993-10-01
931682
Summary Computer aided systems applied to engine, test cells generally consists of a set of microcomputers used as test cell controllers linked to a large mainframe computer or a minicomputer for data processing, analysis and documentation. Nowadays microcomputers with a considerable larger capacity of mass memory are available at very low cost in comparison to conventional minicomputers. Therefore, a computer aided system was conceived based upon two microcomputers linked to a network, allowing data transmission from a test cell station to a remote supervision station placed on the engineering office, and even a certain level of interaction upon the test cell control station. Modularity, flexibility, multi-task capability, as well as easy expansion to other test cells were considered along the system development.
Technical Paper

Study On Dynamics Of Half-Shafts Using Experimental Modal Analysis - Part Two

1993-10-01
931699
This work presents a study on dynamics of homocinetic half-shaft with constant velocity joints using experimental modal analysis. The first topic shows the development of a test rig that allows a representative simulation of the dynamic conditions imposed by the vehicle to the component concerning its first bending mode. Further, it is presented the development of an interative routine that allows the update of an analytical model that represents a dynamic behaviour based on experimental data.
Technical Paper

Modeling And Simulation Of A Five- Point Vehicle Suspension Using Multibody Systems (MBS) Techniques

1993-10-01
931697
The work described in this paper performs the modelling and simulation of a 5-link suspension using multibody systems (MBS) modelling techniques. This suspension concept is used in the class-S Mercedes-Benz. but the numerical data do not correspond to any actual suspension built into their vehicles. The equations of motion were obtained using the MBS equation generator SD/FAST. The simulation was performed with the general purpose simulation program ACSL. Analysis and pre and post processing was carried out with the matrix analysis package MATLAB. The paper discusses aspects related to computational performance of the equation generator and the simulation code. It also discusses suspension behaviour due to its geometric characteristics. Quantities presented are equation complexity and cpu usage for the equation generation phase. Runtime is used to characterise simulation code performance.
Technical Paper

Study Of Vibrations In Driveshafts

1993-10-01
931700
This work presents a study of the bending vibrations of front wheel drive automobile half-shafts, using various theoretical models results in comparison with published experimental data. It’s well known that this kind of noise problem occurs when a vertical excitation frequency generated by the engine equals one of the bending natural frequencies of the half-shaft or its interconnecting shaft[7],[8]. The experimental modal analysis is today the preferred method used in the study of this kind of problem[7]. This work, investigates the determination of the bending natural frequencies of a front wheel drive automobile half-shaft, using the transfer matrix method (TMM)[1],[4] and the finite element method (FEM)[6] in the solution of a theoretical model. This model considers the boundary conditions existing in the vehicle, and also in the solution of other simplified models.
Technical Paper

Finite Element Vibration Analysis Of Light Commercial Vehicles Driveshafts

1993-10-01
931701
The purpose of this paper is to analyze, through the use of the Finite Elements Method, how the flexibility of components at the extremity (clutch housing, gear box, etc.) affects the critical speed of light trucks drivelines. If these flexibilities, are not considered, there will be obtained theoretical critical speeds that, in spite of being corrected by practical factors, are higher than the actual ones.
Technical Paper

Methodology For Characterizing The Road Damaging Dynamics of Truck Tandem Suspensions

1993-10-01
931693
The road damage caused by heavy trucks is accentuated by the dynamic loads excited by roughness in the road. Simulation models of trucks are used to predict dynamic wheel loads, but special models are required for tandem suspensions. Parameter values to characterize tandem suspension systems can be measured quasi-statically on a suspension measurement facility, but it is not known how well they fit dynamic models. The dynamic behavior of leaf-spring and air-spring tandem suspensions were measured on a hydraulic road simulator using remote parameter characterization techniques. The road simulator tests were duplicated with computer simulations of these suspensions based on quasi-static parameter measurements to compare dynamic load performance. In the case of the walking-beam suspension, simulated performance on the road was compared to experimental test data to evaluate the ability of the walking-beam model to predict dynamic load.
Technical Paper

Modeling Of Vehicle Suspension System Using Bond Graphs

1993-10-01
931694
A great interest in active and semi-active suspensions has been arised, and that poses the problem of design a control system, and the first step is the modelling of the vehicle, its suspension, and its interaction with the guide-way. In this paper the multiport model approach and its associcited bond graph representation are suggested to perform the modelling task, since it can cope with a wide range of energy domains, offers clear and succint representation of systems and devices, allows an organized way to develop the system model and is suitable for development as a computer aided modelling software.
Technical Paper

Checking The Suspension Movements Considering The Flexibility Of The Vehicle Structure

1993-10-01
931695
This work presents preliminary results from a research about active suspension control regarding vehicle body flexibility. At first we are examining the use of LQG-LTR method, which allows to consider unstructured uncertanties in the compensator design if the model has the same number of inputs and outputs. The method used makes an inverse of the plant, so it must not have transmission zeros with positive real parts. These requirements create some difficulties, leading to observability problems (probably) in the particular system used in the numerical analisys.
Technical Paper

Modeling Of Dynamic Interaction BetweenThe Structure And The Suspension Of Heavy Vehicles

1993-10-01
931696
The modeling of Vehicle Dynamic has been made with several advantages by the Bond Graph Technique, due its large employment and its computational approach that allows the analysis of complex system. This paper shows the bond graph capacity to represent the distributed parameters system of the vehicle structure that was modeled by the Finite Element Method. Because of the great number of degrees of freedom, we must represent the system by multibonds. This make easy the mathematical manipulations of the equations to obtain the state space model of the problem. We present some results of the simulation where we can interpret the physical behavior of the system over working condition.
Technical Paper

State of the Art in the use of Hidrogen as a Automotive Fuel

1993-10-01
931706
In all the world, the environment problems originated from the intensive petroleum compounds consumption, and the perspective of a future exhaust of this source, has lead to researches of alternative fuels for this compounds, mainly obtained from renewable energy sources. Among many proposed fuel supplement systems, the hydrogen use has deserved outstanding treatment, as in internal combustion motors or in fuel-cells (electric-type vehicles). This work shows the actual art’s state of the hydrogen utilization in automotive uses, analyzing the mainly problems and solutions related to the internal combustion motor adaptation for this application, as the pre-ignition and backfire effect, the power losses by the gaseous fuel usage, the nitrogen oxides emission (unique pollutant emitted in the hydrogen combustion), etc..
Technical Paper

Practical-Theoretical Analisys of Chassis Torsion by Finite Element Analysis

1993-10-01
931705
The structural calculation of a complete light truck frame using the Finite Element Method requires the knowledge of the torsional stiffness of the cargo box, cab and front end of the vehicle. This paper presents a practical way to obtain the necessary data, avoiding the mathematical modeling of the whole vehicle, to reduce time and machine requirements. Lab measurements of the torsional stiffness are performed, in the frame alone and with each of the body components, allowing the definition of a mathematical model for the whole vehicle.
Technical Paper

Rapid Traffic System - Preliminary Study For A Ground Transport System

1993-10-01
931703
This paper summarizes a preliminary study of some alternatives for construction of Rapid Transit System - RTS. For studies approach it was considered an area in the Vale do Paraiba particularly the São José dos Campos City and Jacareí Town. The final conclusion includes a proposal for implementation on the Urban Passengers Transportation System on this zone. The proposal is based on the success of “Step by Step” Program with immediate introduction of Guided Buses and/or Guided Trolley buses. With evolution of urban growing the system can be converted to a Light Rail Vehicle System.
Technical Paper

Theoretical Formulation For Power Losses In Torque Converters

1993-10-01
931702
In this study are equated the main power losses that occur in the torque converters. The mathematical model is developed through empirical methods, taking into consideration the fluid circulation movement similar to the forced vortex. All equations for the fluid flow sections inside the torque converter are derived.
Technical Paper

Vibrations of Laminated Beams

1993-10-01
931704
In this work it is presented an adaptation for beams of Di Sciuva’s theory of laminated plates. This theory accepts that in each lamina plane sections remain plane and other assumptions accepted for isotropic beams. A computer program was made to solve the equations of movement for simply-supported beams. Several results are shown, and it is emphasized the excelent agreement between theoritical and experimental values.
Technical Paper

Lubricity of Low Sulfur Diesel Fuels

1993-10-01
932740
The sulfur content of all highway diesel fuel was required to be reduced to a maximum of 0.05 wt % starting October 1993. This federal requirement results in further fuel processing by refineries. The hydrotreating process used to reduce fuel sulfur has the potential to reduce the fuel's lubricating characteristics. Fuel producers and fuel injection equipment suppliers have been concerned about the likelihood of increased component wear upon the introduction of these new fuels. Low sulfur fuels have been produced and marketed in Southern California since 1985 with no apparent evidence of any field problem. Nevertheless, concern outside of this area exists. Therefore, one such fuel with a sulfur content well below 0.05% was used to conduct a vehicle test to evaluate its effect on the fuel injection pump. This fuel and a low aromatics diesel fuel were used to investigate the effect of various levels of two different sulfur compounds on the lubricity characteristics of the fuels.
Technical Paper

The Analysis of Diesel Engine Turbocharger Vibration Using Time Synchronous Averaging

1993-09-01
932500
Emergency Diesel Generators are used in the nuclear industry for stationary stand-by power in order to safely shut down a reactor unit in the event of loss of off site power. Therefore, a high diesel engine reliability and availability must be maintained. Engine turbochargers often experience operating failures resulting in extended down time and costly repairs. Improved turbocharger vibration testing using time synchronous averaging is one method for evaluating the operating condition of a turbocharger. Typical vibration collection methods result in the turbocharger vibration being masked by the high background noise associated with the reciprocating nature of the engine. Time synchronous averaging reduces the background noise and allows accurate measurement of the 1x RPM component and harmonics of the turbocharger. Trends of the turbocharger vibration may then be established for diagnostic purposes, giving the analyst another tool for improving engine reliability and availability.
Technical Paper

Diesel Oxidation Catalysts with Low Sulfate Formation for HD-Diesel Engine Application

1993-09-01
932499
Stringent standards for the emission of particulate matter by heavy duty diesel engines will come into effect in the nineties in the US and are anticipated to come into effect in the same period in W-Europe and in Japan. This has lead most of the manufacturers to intensify the evaluation of exhaust aftertreatment devices. Although particulate filtering systems proved to be valuable in limited fleet applications, the general introduction did not take place because of complicated and limited durability regeneration. Flow-through catalysts which were introduced for passenger cars in 1989 drew a lot of attention for potential heavy duty diesel applications. In this paper the major parameters affecting the performance of these flow-through catalysts and the particularities related to heavy duty diesel application are outlined. The parameters deal with the fuel sulfur content, the test cycles applied, the catalyst formulation and washcoat composition.
Technical Paper

Power Cylinder Design Variables and Their Effects on Piston Combustion Bowl Edge Stresses

1993-09-01
932491
During engine durability testing of a large diesel engine, several pistons were found to have experienced fatigue cracks along the combustion bowl edge directly over the pin bores. In order to determine the optimum design solution to this piston combustion bowl edge cracking problem, the performance of several power cylinder assemblies have been investigated to determine their effects on piston combustion bowl edge stresses. The power cylinder design variables examined in this analysis were piston skirt section thickness, piston compression height, pin inner and outer diameters and connecting rod end designs (Tee-Pee vs. straight). A finite element analysis of each power cylinder assembly was performed to ascertain the stresses existing on the piston combustion bowl edge. This finite element analysis found combustion bowl edge stresses from the thermal expansion effects only loading as well as those from the combined thermal expansion and combustion pressure loading.
Technical Paper

The Influence of Oxidation Catalysts on NO2 in Diesel Exhaust

1993-09-01
932494
In underground noncoal mines the emission of nitrogen dioxide (NO2) in the exhaust of a diesel engine is more important than the emission of nitrogen oxide (NO) because of the much lower permissible exposure limit for NO2. Consequently, the tendency of aftertreatment devices such as oxidation catalytic converters (OCCs) to oxidize NO to NO2 is counterproductive. The U.S. Bureau of Mines (USBM) is investigating the effects of OCCs upon NO2 emission by using a Fourier Transform Infrared (FTIR) exhaust gas analyzer to compare the concentration of NO2 in diesel exhaust upstream and downstream of the OCC. We find that some OCCs increase the concentration of NO2 much more than others, and that over some temperature ranges the aftertreatment results in an apparent decrease in NO2 concentration.
Technical Paper

NVH Optimization of a 16-Cylinder Diesel Engine

1993-09-01
932492
In the early design stage a 16-cylinder V-engine is optimized with respect to its vibrational and acoustic behavior. The objectives of the development are: (1) to minimize vibrations of the crankcase with special focus on the structure-borne noise transmission via the engine mounts, and (2) in this context, to identify the appropriate locations for the engine mounts. The NVH behavior of the engine structure is simulated using the Finite Element Method (FEM). The dynamic FE-model of the engine is excited via synthesized cylinder pressure force spectra. The corresponding vibrations of the sound emitting surface are calculated, thereby revealing structural weaknesses. By calculation of the crankcase modal vibrations, the noise relevant modes are identified. Based on these results the influence of structural modifications on the NVH behavior is predicted.
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