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Technical Paper

Tire Roller Contact Model for Simulation of Vehicle Vibration Input

1993-11-01
932008
To improve the quantitative accuracy of vehicle vibration studies, a roller contact tire model with the geometric filtering concept and a method to determine the effective road input are proposed. Computer simulation with the 13 DOF vehicle model for a light truck, based on two different tire models, and relevant outdoor tests for measuring the vehicle accelerations of both sprung and unsprung masses are presented. Comparisons of test data and simulation results show that the roller contact tire model renders much better simulation accuracy than the single point contact tire model. It is concluded that the roller contact tire model is a powerful concept which acts as a geometric filter, giving a simple method to calculate the enveloping effects of tires and the effective road elevation input.
Technical Paper

Tire Carcass Camber and its Application for Overturning Moment Modeling

2013-04-08
2013-01-0746
The properties of contact patch are key factors for tire modeling. Researchers have paid more attention to the contact patch shape and vertical pressure distribution. Some innovative concepts, such as Local Carcass Camber, have been presented to explain special tire modeling phenomena. For a pragmatic tire model, a concise model structure and fewer parameters are considered as the primary tasks for the modeling. Many empirical tire models, such as the well-known Magic Formula model, would become more complex to achieve satisfactory modeling accuracy, due to increasing number of input variables, so the semi-empirical or semi-physical modeling method becomes more attractive. In this paper, the concept of Tire Carcass Camber is introduced first. Different from Local Carcass Camber, Tire Carcass Camber is an imaginary camber angle caused only by lateral force on the unloaded tire.
Technical Paper

Simulations of Tire Cornering Properties in Non-Steady State Conditions

1998-02-01
980254
Simulations of tire cornering properties with small-amplitude lateral inputs are carried out in non-steady state conditions. The simulation algorithm is derived and the discrete expressions are presented in detail. Based on the simulations, lateral force and aligning moment can be calculated numerically with time-varying yaw angle and lateral displacement as inputs in spatial domain. The flexibility of both tread and carcass along with tire width is taken into account effectively in the simulations, in which the flexibility of carcass includes translating, bending and twisting flexibility. The simulations in non-dimensional form are associated with four tire structure parameters only, which are non-dimensional parameters reflecting the characteristics of tire stiffness, tire width and contact length. Simulation results are validated by test data from step lateral inputs tests. Several typical simulation results are provided.
Technical Paper

Research on Closed-Loop Comprehensive Evaluation Method of Vehicle Handling and Stability

2000-03-06
2000-01-0694
A closed-loop comprehensive evaluation and a test method for vehicle handling and stability have been studied by using development driving simulator. Simulator test scheme has been designed and carried out with 14 vehicle configurations, and subjective evaluation has been made for easy handling of vehicle by drivers. A closed-loop comprehensive evaluation index has been put forward considering the factors affecting vehicle handling and stability. The reliability of the index has been validated by driver's subjective evaluation. A driver/vehicle/ road closed-loop system model has been established, and the theoretical predictive evaluation has been carried out with 14 vehicle configurations. Simulation showed that similar result for both theoretical predictive evaluation and subjective evaluation.
Technical Paper

Key Items in Tire Non-Steady State Test

2002-07-09
2002-01-2231
In the paper, the Flat Plank Tire Tester of Changchun Automobile Institute is introduced. This paper, according to practical experiences, generalizes some issues in the tire's non-steady state test. In the non-steady state test, it must be assured that the footprint centerline of tire coincides with that of slid platform, which guarantees no sliding motion between tire and slid platform during the movement. Due to tire taper effect and inhomogeneous tire material, when its side slip angle is zero, side force and aligning torque are not zeros, but have initial values. Here two approaches are discussed to eliminate the side force and aligning torque. Besides, other factors in the test are put forward for discussion. Eliminating the interference can obviously improve the test accuracy. This paper also provides test curves of both pure side slip angle input and pure yaw angle input.
Technical Paper

Analysis of Non-Steady State Tire Cornering Properties Based on String-Concept Deformation and Geometric Relationship of Contact Patch

2007-04-16
2007-01-1514
Vehicle handling and stability performances are greatly determined by non-steady state (NSS) tire cornering properties. Analytical derivation of NSS tire cornering models are presented in this paper based on Pacejka's string-concept assumption, in which carcass is assumed to be a stretched string with lateral deformation and lateral relaxation. The lateral inputs of the models are either displacement-based (lateral displacement and yaw angle) or slip-based (slip angle and turn slip). The transient deformations in spatial domain in both longitudinal and lateral directions are obtained directly from geometric relationship of contact patch. The additional self-aligning moment due to longitudinal deformation of contact patch after effect of tire width is considered is also achieved according to geometric relationship of contact patch in longitudinal direction and two transient geometric conditions of contact point.
Technical Paper

Analysis of Automotive Handling Based on Tire Cornering Properties in Non-Steady State Conditions

1999-11-15
1999-01-3758
Non-steady state (NSS) tire cornering properties show obvious differences from steady state (SS) tire cornering properties. A two-DOF automobile model with steer angle as an input is established based on the known NSS tire model considering complex carcass deformation. The tire model can certainly be applied to modelling of a multi-DOF automobile system. The frequency responses of lateral acceleration and yaw rate are then derived. An evaluation index, amplitude-frequency characteristic of relative error (AFCRE), is used to analyze the influences of NSS front wheels (FW) and/or rear wheels (RW) on automotive handling. The influences of NSS FW are much greater than those of NSS RW only on automotive handling. The established automobile model can also be applied to other similar studies of vehicle dynamics.
Technical Paper

An Empirical Tire Model for Non-Steady State Side Slip Properties

2003-11-10
2003-01-3414
In this paper, on the basis of the extant semi-empirical tire models of non-steady state with pure yaw angle input and pure side slip angle input, two empirical tire models of non-steady state side slip properties are established, one is pure yaw angle input, the other is pure side slip angle input, and both of them have been verified by test data. These two models can be used to approximately express tire force within low frequency. They have their own advantages, and make up for the disadvantages of existing tire models. They provide more choice for the simulation of vehicle dynamics.
Technical Paper

An Efficient Assistance Tool for Evaluating the Effect of Tire Characteristics on Vehicle Pull Problem

2020-04-14
2020-01-1237
The vehicle pull problem is very important to driving safety. Major factors that may cause the pull problem related to tire include variations of geometric dimension (eg.RPK) and stiffness (eg. cornering stiffness, Aligning stiffness), Plysteer and Conicity effect. In the previous research, the influencing mechanism of these factors were well studied.But in fact, vehicle pull problem caused by tire is probabilistic. When we assemble four tires onto the car, there would be 384 kinds of assembly arrangements. If we want to evaluate the pull performance of all these arrangements by real test, it will take a very long time, almost 24 working days, and along with a high test cost. Therefore, it is very needed to develop an assistant simulation tool that can evaluate the effect of tire characteristics on vehicle pull problem quickly.
Technical Paper

A Study of Tire Lag Property

2001-03-05
2001-01-0751
Tire lag property is a basic property of tire dynamics, and it has significant influence on the performance of vehicle dynamics. In distance domain, the side force and moments produced by a massless tire are basically displacement or path frequency dependent, rather than time dependent. In the paper, on the basis of the stretched-string model, the first-order filtering of deflection for the front point of the contact print and the first-order filtering of side force have been introduced. Tire system can be regarded as a first-order linear system under small slip angle. The force response of tire has the characteristics of the responses of first-order linear system under small angle. The relaxation length is an important parameter in studying tire lag property. It decreases with increasing slip angle. It plays an important role in the study of tire transient properties.
Technical Paper

A Prediction Method for Tire Combined Slip Mechanical Properties from Pure Slip Test Data

2020-04-14
2020-01-0896
A high-precision handling tire model is needed for the tire and vehicle matching research, now the popular Magic Formula tire model is an empirical model, which requires the pure and combined test data to identify the model parameters. Although MTS Flat-trac is an efficient tire test rig, but a complete set of handling tire model tests still need much time and high cost. Therefore, it is very meaningful to explore a high accuracy method for predicting tire complex mechanical properties with as few test data as possible. In this paper, a method for predicting tire combined slip characteristics from pure cornering and pure longitudinal test data is studied, and verified by comparing with the test data. Firstly, the prediction theory of UniTire model is introduced, and the formula for predicting combined slip characteristics based on constant friction coefficient is derived.
Technical Paper

A Non-steady and Non-linear Tire Model Under Large Lateral Slip Condition

2000-03-06
2000-01-0358
The objective of this study is to develop a non-steady & non-linear tire model for vehicle dynamic simulation and control for extreme lateral slip condition. This model is provided in a semi-analytical form based on the theoretical non-steady state model, presented at 2nd IAVSD Tyre Conference, Feb. 1997[6]. The tire model is based on a quasi-steady state concept, which generates the dynamic forces and moment according to the dynamic effective slip ratio cooperating with the Unified Semi-Empirical Tire Model for Steady State. Satisfying the theoretical boundary conditions at two sides (lowest & highest) in frequency domain, the tire model is capable of describing the transient force & moment characteristics of tires in higher frequency range, Comparing with the “Linear Approximation” model, presented at 4th AVEC Conference, Sept. 1998[4].
Technical Paper

A Driver Direction Control Model and its Application in the Simulation of Driver-Vehicle-Road Closed-Loop System

2000-06-06
2000-01-2184
The research of driver behavior characteristics has been a focus of vehicle handling and stability performance. With the driver preview effort, many different driver preview models of direction control have been proposed and the simulations of driver-vehicle-road closed-loop system made. But in the simulation, most of the conventional models have the same precondition that the road was simply described as a pre-given preview course. How to simulate the driver dynamically deciding vehicle preview course based on the real road circumstance is the key to the further research of the driver model. In this paper, a new driver direction control model is established, which is called the Optimal Preview Lateral Acceleration (OPLA) Model and divided into three sub-models: driver’s information identification model, driver’s fuzzy decision model of vehicle preview course and driver’s performance first-order correction model.
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