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Technical Paper

A New Apparatus to Evaluate Lubricants for Space Applications - The Spiral Orbit Tribometer (SOT)

2000-06-19
2000-01-1828
Lubricants used in space mechanisms must be thoroughly tested prior to their selection for critical applications. Traditionally, two types of tests have been used: accelerated and full-scale. Accelerated tests are rapid, economical, and provide useful information for gross screening of candidate lubricants. Although full-scale tests are more believable because they mimic actual spacecraft conditions, they are expensive and time consuming. The spiral orbit tribometer compromises between the two extremes. It rapidly determines the rate of tribochemically induced lubricant consumption, which leads to finite test times, under realistic rolling/pivoting conditions that occur in angular contact bearings.
Technical Paper

Analysis of Vehicle Response Data Measured During Severe Maneuvers

2000-05-15
2000-01-1644
During the past few years, the National Highway Traffic Safety Administration's (NHTSA) Vehicle Research and Test Center has generated a plethora of reliable vehicle test data during their efforts to study vehicle rollover propensity. This paper provides further analyses of a small selection of some of the data. The analyses provided here derive in part from the previous work, trying to answer some of the questions spawned by earlier analyses. The purpose of this paper is to introduce several new concepts to the study of vehicle roll stability and provide case studies using the results available from the NHTSA testing. Results from several severe maneuvers are studied in detail to gain understanding of vehicle response in these cases.
Technical Paper

Investigation of a Roll Control System for an Off-road Vehicle

2000-05-01
2000-01-1646
The current popularity of the Sport Utility Vehicle (SUV) market has led to new developments aiming to increase product performance. Such vehicles pose a significant challenge as they must perform to a high standard over a large variety of road conditions. Previously, emphasis has been placed on off-road ability. However, SUVs are now seen as an alternative to conventional luxury cars, and hence are expected to perform similarly, but without significantly degrading off-road performance. The introduction of a roll control system can achieve body roll levels lower than a conventional sports saloon, whilst improving off-road ability by removing the compromises associated with conventional anti-roll bars. This paper investigates the characteristics of such a system by developing a computer simulation of the vehicle and the associated roll control scheme.
Technical Paper

Fundamental Physics Behind New Suspension Concept for Automobiles

2000-05-01
2000-01-1647
The Transverse Leaf suspension with Superior Roll Axis is a new suspension concept for automobiles. It enables the load transfer during a turn to be more evenly redistributed between the two wheels on the same axle thus optimizing its tires lateral force capabilities. The TLSRA concept is made up of a single transverse leaf spring linking the middle of the sprung mass to the outer end of 2 transverse suspension arms per axle. Those transverse arms are mounted close to the middle of the sprung mass with their attachment points located above the mass centroïd. Each wheel assembly is mounted directly onto the free end of its respective suspension arm. Because body roll is now counteracting vertical load transfer during transient and permanent operating conditions, this suspension enables designers to keep spring stiffness low without compromising road handling.
Technical Paper

Elimination of Roll, Squat, and Dive Through Biased Suspension Response

2000-05-01
2000-01-1632
Conventionally sprung vehicles are subject to rolling and pitching of the sprung load as the vehicle corners and accelerates, respectively. Designs which incorporate active elements seek to control these movements, frequently resulting in compromised performance or reduced fuel economy. This paper considers the possible replacement of conventional springs, shocks, and anti-sway bars with specified fluid spring components. The fluid spring components offer biased response to dynamic load variations in the following manner: provide support of the sprung load equal to the magnitude of the load at each moment, and either compressing readily to absorb upward forces originating in the wheel assembly which exceed the magnitude of the load at that moment, or extending rapidly to provide support equal to the magnitude of the load at that moment, in the event the wheel assembly tracks through a hole.
Technical Paper

Review of Parameters Affecting Stability of Partially Filled Heavy-Duty Tankers

1999-11-15
1999-01-3709
Partially filled tanker trucks are susceptible to rollover instabilities due to fluid sloshing. Due to the catastrophic nature of accidents involving the rollover of tanker trucks, several investigations have been conducted on the parameters affecting stability of partially filled heavy-duty tankers. Since stability of heavy-duty tankers undergoing on-road maneuvers such as braking, and/or lane changing has been an issue that concerned many researchers for a long time, a literature review has been conducted which underlines the most important contributions in this field. This review covers work done in the field of fluid-structure interaction, yaw and roll stability of heavy-vehicles, and fluid-vehicle dynamic interaction. In addition, vehicle stability issues are addressed such as jack-knifing, side slipping, vehicle geometry and container geometry among others.
Technical Paper

Optimal Tank Geometry to Enhance Static Roll Stability of Partially Filled Tank Vehicles

1999-11-15
1999-01-3730
A generic tank cross-section is formulated to describe the geometry of currently used tanks in transportation of fuel oils and bulk liquids, and to explore optimal tank geometry for enhancement of roll stability limit of tank vehicle combinations. The tank periphery, composed of 8 circular arcs symmetric about the vertical axis, allows more design flexibility in view of the roll stability limits than the conventional tank shapes. A shape optimization problem is formulated to minimize the overturning moment imposed on the vehicle due to c.g. height of the liquid load, and the lateral and vertical movement of the liquid bulk within the partly filled tank. Different optimal tank cross-sections are proposed corresponding to varying fill conditions, while the total cross-sectional area, overall height and overall width are constrained to specified values.
Technical Paper

Anti-Slosh Damper Design for Improving the Roll Dynamic Behavior of Cylindrical Tank Trucks

1999-11-15
1999-01-3729
The slosh forces arising due to liquid motion in partially filled containers affect the roll dynamic stability of tank vehicles. In this paper, a simplified dynamic truck roll model has been developed considering both suspension flexibility and nonlinear dynamics of the liquid cargo motion. A small-scale experimental model for a cylindrical truck tank, excited in the lateral direction, is designed and constructed to measure the viscous damping and damped natural frequency of the liquid cargo. Since the viscous damping of the liquids is limited by its natural characteristics, partitions containing rectangular slots and holes of different sizes are used to generate additional damping. It is fitted against the lateral motion of the liquid slosh, i.e. parallel to and passing through the longitudinal axis of the vehicle. These types of partitions increase the motion damping of the liquid cargo and make the liquid behave like a dynamic absorber.
Technical Paper

Optimal Suspension Damping for Improved Driver- and Road- Friendliness of Urban Buses

1999-11-15
1999-01-3728
Dynamic interactions of urban buses with urban roads are investigated in view of the vibration environment for the driver and dynamic tire forces transmitted to the roads. The static and dynamic properties of suspension component and tires are characterized in the laboratory over a wide range of operating conditions. The measured data is used to derive nonlinear models of the suspension component, and a tire model as a function of the normal load and inflation pressure. The component models are integrated to study the vertical and roll dynamics of front and rear axles of the conventional and modern low floor designs of urban buses. The resulting nonlinear vehicle models are thoroughly validated using the fieldmeasured data on the ride vibration and tire force response of the buses.
Technical Paper

Springback of Sheet Metal Subjected to Multiple Bending-Unbending Cycles

2000-03-06
2000-01-1112
A Draw Bead Simulator (DBS), with modified draw beads, was employed in this study to understand the springback behavior of sheet metal subjected to multiple bending-unbending cycles. The investigations were carried out in both the rolling and the transverse rolling directions on four types of materials: Electro-Galvanized DQ steel, light and heavy gauge Hot-Dip Galvanealed High Strength Steels, and Aluminum alloy AL6111. The sheet geometries, thickness strains, pulling forces and clamping forces were measured and analyzed for the purpose of establishing a benchmark database for numerical predictions of springback. The results indicate that the springback curvature changes dramatically with the die holding force. The conditions at which the springback is minimized was observed and found to depend on the material properties and the sheet thickness. Analysis with an implicit FEM showed that the predicted and the experimental results are in very good agreement.
Technical Paper

Accident Reconstruction of Rollovers - A Methodology

2000-03-06
2000-01-0853
There is little debate that reconstructing a rollover crash presents complex multi-dimensional challenges to the reconstructionist. Real world rollovers often cover large amounts of various terrains and typically involve multiple ground impacts. The possible vehicle orientations throughout the roll are almost unlimited. It is also clear that the complexities of these events have placed practical limitations on the abilities for both analytical and experimental models to accurately recreate specific real world rollover collisions. The fundamentals of accident reconstruction do still apply, however, and much valuable and insightful test data is available. This paper will describe a practical methodology and protocol to assist reconstructionists in reconstructing both on-road and off-road rollover accidents.
Technical Paper

Multiple Coherence Analysis on Engine Degree of Freedom Study for Exhaust System Testing

2000-03-06
2000-01-1193
An Automotive Exhaust System Structural Key Life Test has been successfully developed, in part, due to investigations into the boundary conditions of powertrain input. The powertrain (engine and trans-mission) degree-of-freedom study (here after referred to as engine) was investigated in order to determine the sensitivity of the exhaust system to engine motion. Understanding engine motion was necessary in order to establish proper control strategy in the laboratory simulation process. Accurate reproduction of exhaust system response to input road load events was crucial to reproducing known exhaust system fracture modes in early life wear-out conditions. A method multiple coherence analysis has been used to analytically measure the degree of severity between engine input motion and exhaust system output response by analyzing dynamic strain and acceleration. Removing one engine control input at a time, a multiple coherence function was calculated and the exhaust response computed.
Technical Paper

Development of a New Life Equation for Ball and Roller Bearings

2000-09-11
2000-01-2601
The conventional rolling bearing life equation (1), which is based on the theory of Lundberg and Palmgren, has a problem in that it does not match the actual bearing life in all operating conditions. For instance, while the actual life of a bearing under clean lubrication is 20 times longer than the calculated life, actual life under contaminated lubrication is as low as one-tenth of the calculated life. To solve this problem, the following life equation (Eq. 1: Advanced Bearing Life Equation) was developed with the aNSK life modification factor: The new aNSK factor is based on data from bearing life aNSK tests involving over 450 roller bearings and over 550 ball bearings under a variety of operating conditions. The new life equation with the aNSK factor showed a satisfactory fit between calculated life and actual life.
Technical Paper

Film-Forming Properties of Zinc-Based and Ashless Antiwear Additives

2000-06-19
2000-01-2030
A progressive reduction in the permitted level of phosphorus in lubricating oils, coupled with concern to maintain engine and transmission durability, means that it is becoming increasingly important to understand the detailed mechanism of antiwear additive behavior. This paper describes a new experimental technique, which is able to measure both the thickness and distribution of antiwear additive films in rolling/sliding contacts. This enables the kinetics of antiwear film build-up to be investigated and the influence of the reaction film on friction and wear to be monitored. In the current paper, this technique is used to compare the film-forming behavior of ash-containing and ashless antiwear additives.
Technical Paper

THE VIRTUAL PROTOTYPE OF AN OFF-ROAD VEHICLE

2001-06-04
2001-06-0250
In paper, the virtual prototype of the rolling – guiding – suspension system of an off-road vehicle is presented. The prototype has been made with the MBS software ADAMS, and takes into consideration the geometric restrictions as well as the nonlinear characteristics of the elastic and damping elements. The experiment designed is one frequently carried by the automotive manufacturers, namely dynamic with shock test, which consists in the sudden release of the car to fall on the ground from a given height. On the virtual prototype, a lot of measurements have been made having in view to optimize the dynamic behavior of the suspension system and to enhance the vehicle safety.
Technical Paper

Computer Simulation of Vehicle Handling Behaviour by Rigid Body/Finite Element Modeling

2001-01-10
2001-26-0031
A 3-degrees of freedom rigid body model has been developed to predict the directional response of a light passenger vehicle. An attempt has also been made to modify and use the finite element model developed for determining the vibration response of the vehicle to predict the directional response of the vehicle. The Newmark time integration scheme has been used as solver. The tyre properties such as lateral stiffness, cornering stiffness, self-aligning torque stiffness have been measured using the facilities of (CIRT) Central Institute of Road Transport, Pune. The simulation results of directional response of the vehicle in terms of roll angle, yaw rate and lateral acceleration for the sinusoidal and ramp steering inputs (applicable in tests such as the Slalom test and J-turn manoeuvre respectively) to the vehicle at constant speed have been presented.
Technical Paper

Post-Machining Distortion of Formed Fuselage Frame Segments

2001-09-10
2001-01-2594
Process development work was conducted to develop a machined fuselage frame concept for a small (5 abreast) commercial airplane. To minimize detail fabrication cost and to facilitate lean manufacturing, roll forming was identified as the preferred forming process. To reduce assembly costs, long frame segments were desired to minimize the number of frame splices. Since plate stock is limited to lengths of approximately 3.66 meters (12 feet), formed aluminum extrusions were selected as the raw material form. Roll forming and stretch forming process paths were screened for both J section and rectangular bar extrusions. The post machining distortion produced in formed extrusion and plate hog-out frame segments was compared to each other and to process standards governing allowable fit-up forces. As a result of this process development activity, a producible roll forming process path was developed.
Technical Paper

Rolling Contact Fatigue Tests of Selectively Densified Materials

2001-10-01
2001-01-3285
Selectively densified rollers from Distaloy DC-1, Astaloy Mo and Distaloy AE have been rolling contact fatigue (RCF) tested on a ZF-test rig. The rolling contact fatigue endurance limit of the Astaloy Mo based material is approximately 1500 MPa that can be compared to the selected reference material, AISI 5115 (DIN 16MnCr5), 1600 MPa. For the diffusion-alloyed materials, Distaloy DC1 and Distaloy AE, it was not possible to determine the endurance limit due to too few tests. However, the endurance limit seems to be slightly lower than the Astaloy Mo material. The case depth seems to be low for all materials, but the effect appears to be more severe for the Distaloy DC1 material. Surface cracks of different character could be found in all specimens. Small cracks associated with smaller pits are found on the run outs (>50·106 cycles).
Technical Paper

A Neural Network Approximation of Nonlinear Car Model Using Adams Simulation Results

2001-10-01
2001-01-3324
A neural network model of a full car has been developed here on the basis of ADAMS simulation results. The model basically intended for roll control studies, is a completely non-liner model and has 104 degrees of freedom. ADAMS software has been used to determine the model behavior to specific steering inputs. The out put of the simulation program was then used to train a neural network constructed to approximate the model for controller design and real time studies of control action. Specific time delayed feedback inputs to the neural network resulted an efficient approximate model with good accuracy for control tasks.
Technical Paper

Tailored Hybrid Blanks in Steel and Aluminium

2001-10-16
2001-01-3092
Thyssen Tailored Hybrid Blanks (THB) are cold-formable combinations of steel and aluminium sheets. They include linear lap joints fabricated by means of a laser-assisted roll bonding technique. The initial development work has meanwhile progressed to the stage where a pilot line is set to start up operation and fabricate hybrid blanks in shapes and sizes required for automotive engineering applications. The present state of development, a possible spectrum of products, and main process parameters are discussed. Research into the forming behaviour of hybrid blanks is looked at, citing practical examples, added with findings from metallographic analyses and corrosion testing.
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