Tire Interface Research Articles

Traffic-generated emissions of ultrafine particles from pavement–tire interface

In a road simulator study, a significant source of sub-micrometer fine particles produced by the road–tire interface was observed. Since the particle size distribution and source strength is dependent on the type of tire used, it is likely that these particles largely originate from the tires, and not the road pavement. The particles consisted most likely of mineral oils from the softening filler and fragments of the carbon-reinforcing filler material (soot agglomerates). This identification was based on transmission electron microscopy studies of collected ultrafine wear particles and on-line thermal treatment using a thermodesorber. The mean particle number diameters were between 15–50 nm, similar to those found in light duty vehicle (LDV) tail-pipe exhaust. A simple box model approach was used to estimate emission factors in the size interval 15–700 nm. The emission factors increased with increasing vehicle speed, and varied between 3.7×10 11 and 3.2×10 12 particles vehicle −1 km −1 at speeds of 50 and 70 km h −1. This corresponds to between 0.1–1% of tail-pipe emissions in real-world emission studies at similar speeds from a fleet of LDV with 95% gasoline and 5% diesel-fueled cars. The emission factors for particles originating from the road–tire interface were, however, similar in magnitude to particle number emission factors from liquefied petroleum gas-powered vehicles derived in test bench studies in Australia 2005. Thus the road–tire interface may be a significant contributor to particle emissions from ultraclean vehicles.

Tyre model performance test: First experiences and results

The tyre model performance test (TMPT) provides information about the efficiency and problems of the simulation sequence from tyre measurements (tyre modelling and parametrization) to multibody-system (MBS) software integration. Based on test rig tyre measurements with respect to vehicle-handling behaviour and higher-frequency-range tests (running over a cleat; vibration modes), tyre models have to be provided in a way that they can be connected with the standard Tyre interface (STI) or a modified tyre interface to at least one of the three MBS programs ADAMS, DADS and SIMPACK. The test conditions and the simulation test rig were defined in advance by an international group of experts. Four tyre model providers participated for the handling (low-frequency) manoeuvres and four for the low- and higher-frequency-ranges. Since a planned feedback from the MBS simulation results (they were done by the MBS-program providers) to the tyre model providers was not completely finished, the results shown are preliminary only. For the steady-state behaviour, all tyre models show good agreement with measurements for lateral and longitudinal tyre forces while, for the self-aligning torque, larger differences appear. For ‘crossing of a cleat’, all high-frequency-range models show good agreement with measurements as well but, for some tests (e.g. sinusoidal sweeps), qualitative differences even between MBS programs for the same tyre model can be noticed. This indicates that the application of tyre models within MBS programs requires some preliminary testing and maybe additional checks before using them for vehicle dynamics analysis.

A new tyre–soil interaction model for vehicle simulation on deformable ground

In cooperation with the Ford Research Center Aachen the new tyre–soil interaction model AS2TM for MATLAB/Simulink was developed by Automotive Engineering, Software and Consulting (AESCO). The model is based on the principles introduced by Bekker [Bekker, M.G., 1956, Theory of Land Locomotion: The Mechanics of Vehicle Mobility (Ann Arbor, Michigan: University of Michigan Press); Bekker, M.G., 1960, Off the Road Locomotion (Ann Arbor, Michigan: University of Michigan Press); Bekker, M.G., 1960, Introduction to Terrain–Vehicle Systems (Ann Arbor, Michigan: University of Michigan Press).] and by Janosi and Hanamoto [Janosi, Z. and Hanamoto, B., 1961, Analytical determination of draw bar pull as a function of slip for tracked vehicles in deformable soils. Proceedings of the 1st International Conference of the International Society for Terrain–Vehicles Systems, Turin, Italy.] and takes advantage of more than a decade of research work in the field of terra-mechanics at the former Institut für Kraftfahrwesen und Kolbenmaschinen of the University of the Federal Armed Forces Hamburg under the charge of Professor I.C. Schmid. In this paper, firstly, the theoretical approach of AS2TM is discussed and the implementation of significant soft soil–elastic tyre interaction effects described and, secondly, the stand-alone model has been investigated and validated for steady-state conditions by using a virtual tyre test environment. Furthermore AS2TM is implemented as an S function into veDYNA applying the TYDEX standard tyre interface. The vehicle dynamic behaviour on deformable ground in a full vehicle simulation is highlighted and a comparison of the predicted vehicle performances on various terrains is presented.

Experiences with the TYDEX standard tyre interface and file format

The tyre is a complex part of a vehicle simulation model. The parameters are mostly determined from dedicated experiments and the tyre model itself is generally developed by specialists and may have to be coupled to a number of different simulation packages. The former TYDEX Workshop has defined standards to facilitate these processes. The application of these standards by TNO Automotive in the Delft-Tyre product line and some practical experience gained over the years will be discussed. Furthermore limitations of the current standard are discussed and some suggestions for improvements are given, which are particularly relevant for the next generation of dynamic tyre models.

Interface Pressures of a Tractor Drive Tyre on Structured and Loose Soils

An 18·4R38 radial-ply tractor drive tyre was operated at 10% travel reduction, at three correctly inflated combinations of dynamic load and inflation pressures on a structured clay soil and at another combination of load and inflation pressure on a loose sandy loam and a loose clay loam soil. Soil–tyre interface pressures on the face of one lug and on an undertread region between two lugs were measured, and were used in estimating the tyre footprint area for the operating tyre. On the structured clay soil, the interface pressures on the lug face were substantially greater than tyre inflation pressure and those on the undertread were considerably less than inflation pressure. On the loose sandy loam and the loose clay loam, some interface pressures on the lug face exceeded inflation pressure by only a small amount and others were a small amount less than inflation pressure, while undertread pressures were less than inflation pressure. Tyre footprint areas on the structured clay soil were nearly equal for the three correctly inflated load and inflation pressure combinations. The footprint area on the loose sandy loam was 10% greater, and that on the loose clay loam was 4% greater, than the average of the three footprint areas on the structured clay soil.

THE INCORPORATION OF TIRE MODELS INTO VEHICLE SIMULATIONS

Abstract After outlining the different requirements for tire models to be used in full vehicle simulations, a general tire interface to ADAMS will be presented. This interface consists of a library of different tire models and allows user-defined models, too. Special attention will be drawn to the determination of the Pacejka constants from standard tire measurements.

Prediction of Rain Groove Wandering

Summary A new theory to predict rain groove wandering was proposed in which the effect of pattern geometry, sipes, tread stiffness and pitch length on rain groove wandering could be predicted. The mechanism of rain groove wandering was explained by the residual lateral force generated at the interface of tire and road due to rain groove. The peak to peak value of the residual force F pp was found out as the criteria of rain groove wandering and the correlation of F pp and subjective feeling was 0.9, even though complicated practical patterns were included in this correlation study.

Tire Contact Stresses and Their Effects on Instability Rutting of Asphalt Mixture Pavements: Three-Dimensional Finite Element Analysis

Instability rutting generally occurs within the top 2 in. of the asphalt layer when the structural properties of the asphalt concrete are inadequate to resist the stresses imposed on it. Several researchers have presented observations in attempts to explain instability rutting, but a clear identification of the mechanism does not exist. Stresses in the asphalt layer caused by measured tire interface stresses were analyzed in three dimensions by using finite elements to identify possible mechanisms for instability rutting. The analysis showed that radial tires produce high near-surface shear stresses at low confinements, which are not predicted with traditional uniform vertical loading conditions, in the region where instability rutting is known to occur. The resulting shear stresses tend to be shallower than for the uniformly loaded case, and they are focused in areas where instability rutting has been observed. The observed stress states imply that the characterization of instability rutting requires testing at these low confinement (and sometimes tensile) stress states, rather than at the higher stress states typically used in the strength characterization of mixtures.

User-Appropriate Tyre-Modelling for Vehicle Dynamics in Standard and Limit Situations

Summary When modelling vehicles for the vehicle dynamic simulation, special attention must be paid to the modelling of tyre-forces and -torques, according to their dominant influence on the results. This task is not only about sufficiently exact representation of the effective forces but also about user-friendly and practical relevant applicability, especially when the experimental tyre-input-data is incomplete or missing. This text firstly describes the basics of the vehicle dynamic tyre model, conceived to be a physically based, semi-empirical model for application in connection with multi-body-systems (MBS). On the basis of tyres for a passenger car and a heavy truck the simulated steady state tyre characteristics are shown together and compared with the underlying experimental values. In the following text the possibility to link the tyre model TMeasy to any MBS-program is described, as far as it supports the ‘Standard Tyre Interface’ (STI). As an example, the simulated and experimental data of a heavy truck doing a standardized driving manoeuvre are compared.

Standardization in Tire Modeling and Tire Testing — TYDEX Workgroup, TIME Project

Abstract As a result of the 1st International Colloquium on Tire Models for Vehicle Dynamics Analysis in 1991, the international TYDEX Workshop working group was established. This workshop concentrated on the standardization of the exchange of tire measurement data and the interface between tire and vehicle models in order to improve the communications between vehicle manufacturers, suppliers, and research organizations. The development and knowledge of tire behavior is of great importance to both the tire and vehicle industries and will be intensified. Therefore the TYDEX Workshop received great interest from all parties to come to some kind of standardization. In the two expert groups, one of which focused on Tire Measurements — Tire Modeling and the other on Tire Modeling — Vehicle Modeling, the TYDEX-Format and the standard tire interface have been developed, which will be explained in this paper. Furthermore, a short overview of the European TIME project aiming at a standard tire testing procedure will be given, which is reliable and consistent with realistic driving conditions. Standard testing procedures are some of the important consequences of the TYDEX Workshop.

TYDEX Workshop: Standardisation of Data Exchange in Tyre Testing and Tyre Modelling

ABSTRACT As a result of the ‘1st International Colloquium on Tyre Models for Vehicle Dynamics Analysis’ in 1991, the international ‘YDEX Workshop’ working group was established. This workshop concentrated on the standardisation of the exchange of tyre measurement data and the interface between tyre and vehicle models in order to improve the communication between vehicle manufacturers, suppliers and research organisations. The development and knowledge of tyre behaviour is of great importance to both tyre and vehicle industry and will be intensified. Therefore the TYDEX Workshop showed great interest from all parties to come to some kind of standardisation. In the two expert groups - one focused on Tyre Measurements - Tyre Modelling and the other on Tyre Modelling - Vehicle Modelling - the TYDEX-Format and the Standard Tyre Interface have been developed, which will be explained in this paper. Furthermore a short overview of the European TIME project aiming at a standard tyre testing procedure will be given, which is reliable and consistent with realistic driving conditions. Elaborating standard testing procedures is one of the important consequences from the TYDEX Workshop.

THE INCORPORATION OF TIRE MODELS INTO VEHICLE SIMULATIONS

Abstract After outlining the different requirements for tire models to be used in full vehicle simulations, a general tire interface to ADAMS will be presented. This interface consists of a library of different tire models and allows user-defined models, too. Special attention will be drawn to the determination of the Pacejka constants from standard tire measurements.

Interfacial Tensions And Aging Behaviour of Some Crude Oils Against Caustic Solutions

Abstract Interfacial tensions between sodium hydroxide solutions and four crude oils were measured as a preliminary step in the investigation of caustic waterflooding possibilities. Based on these initial results and some laboratory caustic flood tests reported in the literature; the Wainwright and Viking Kinsella Wainwright B heavy oil reservoirs are possible candidates for improved oil recovery by caustic waterflooding. Core displacement measurements or pilot floods will, however, be required to evaluate actual benefits from the process. A minimum interfacial tension between these heavy oils and caustic solutions occurs with about O.25wt. % NaOH injection water. The interfacial tension between the erode oils and sodium hydroxide solutions was found to release with the age of tire interface. This behaviour suggests that many of the sodium soap products, which are formed when acidic compounds in the crude oil react at the interface with sodium ions in the aqueous phase, subsequently migrate away from the oil-water interface. Introduction The current upswing in improved recovery research has resulted in several recent reports of laboratory studies and field trials of caustic waterflooding processes. This work has been discussed in detail by Johnson(1) and Ehrlich et al.(2). Several controlling mechanisms all relying on changing the properties of some of the interfaces involved, have been identified or suggested as being responsible for improving the recovery aver that of a conventional waterflood. Reisberg and Doscher(3) indicated that interfacial tension lowering and the elimination of rigid films at oil/water interfaces were responsible for an improved ultimate recovery in laboratory displacement experiments, Others(2, 4–6) have tested relatively high NaOH concentrations for alkaline waterflooding in light oil reservoirs where the controlling mechanism appeared to be a wettability change from oil-wet to water-wet. A caustic process has also been used with saline water, in which there was a wettability change from water-wet to oil-wet and the production of a water-in-oil emulsion(7). Workers at Chevron Oil Field Research (8, 9) found significant increases in viscous oil recovery before water breakthrough, and have attributed this to a reduction in water channelling- which results from residual oil being emulsified in situ at low interfacial tensions (oil-in-water emulsion) and then becoming trapped again in small pare throats, Johnson's recent paper(1) also discusses the emulsification and entrainment mechanism, in which emulsified oil is produced rather than becoming trapped. A mobility-controlledaustic flooding process has been outlined by Sarem(10) and is currently being field tested(11). Friedman recently suggested using polyethylenimine, a polybasic polymer, for the recovery of viscous acidic crudes(12). The present study was concentrated on interfacial tension determinations between four Canadian crude oils and caustic solutions. Most of the measurements were with heavy oil of 21–22 º API gravity" from the Wainwright and Viking Kinsella Wainwright B pools in Alberta. Scott et al.(13) and Dranchuk et al.(14) have reported a number of alkaline waterflood tests with heavy ail primarily from the Lloydminster area.