Showing papers in "Tire Science and Technology in 2003"

Prediction of Tire Tread Wear with FEM Steady State Rolling Contact Simulation

Abstract: A procedure based on steady state rolling contact Finite Element Analysis (FEM) has been developed to predict tire cross section tread wear profile under specified vehicle driving conditio...

Prediction of Snow/Tire Interaction Using Explicit FEM and FVM

Abstract: A three‐dimensional prediction model has been developed in which the interaction between snow and a rolling tire with tread pattern is considered. An explicit finite element method (FEM) and a finite volume method (FVM) are used to model tire and snow respectively. Snow deformation is calculated by the Eulerian formulation to solve the complex interaction between snow and tire tread pattern. Coupling between a tire and snow is automatically computed by the coupling element. Numerical modeling of snow is essential to the tire performance prediction on snow. In this study, snow is assumed to be homogeneous and considered to be an elasto‐plastic material. The Mohr‐Coulomb yield model, in which the yield stress is a single function of pressure, is adopted. This function is investigated by tire traction tests under a wide range of tire contact pressures using several tires with different inflation pressures and patterns. The predicted results using the Mohr‐Coulomb yield model are compared with those ...

Evaluation of Tire Tread and Body Interactions in the Contact Patch

Abstract: Today's tread pattern design development is done independently from the tire body construction in order to achieve the best traction and uniform local wear performance. Nevertheless, a better understanding of the interaction between tread and body is necessary to improve the above mentioned properties. An identical tire has been investigated in four pattern steps, starting from a smooth tire, carving a block structure with longitudinal and lateral grooves, and finishing with additional sipes in the blocks. A new developed test stand, which is capable of measuring the stresses in the contact patch of the rolling tire in all directions with a resolution of 1 mm, is described. The local contact stresses of the investigated tread blocks are simulated by FEA using the measured loading conditions of the smooth tire. The results of this simulation are compared with measurements and mechanically interpreted.

Transient Finite Element Analysis of Tire Dynamic Behavior

Abstract: Dynamic behavior of a pneumatic tire is simulated by use of an explicit finite element (FE) code. Different parts of the tire and their corresponding material properties are taken into account in the FE model because they play a significant role in tire dynamics. The work presented in this study discusses simulation of cornering behavior, braking behavior, and combined cornering‐cum‐braking behavior. The effects of camber angle and grooved tread on tire cornering behavior are discussed. ABAQUS/Explicit, a general non‐linear FE code, was used for these simulations. To predict the Magic Formula characteristics over a complete range, various simulations are performed at different normal loads and operating conditions. Predicted Magic Formula curves from the simulation results for various dynamic conditions closely follow the experimental data curves. Even though these simulations demand huge computational resources, the predicted Magic Formula curves can be directly used as input in the complete stu...

Simplified Approach to Calculating Geometric Stiffness Properties of Tread Pattern Elements

Abstract: The influence of tread designs on tire performance is well known. The tire industry spends significant effort in the development process to create and refine tread patterns. Creating an aesthetic yet functional design requires characterization of the tread design using many engineering parameters such as stiffness, moments of inertia, principal angles, etc. The tread element stiffness is of particular interest because of its use to objectively determine differences between tread patterns as the designer refines the design to provide optimum levels of performance. The tread designer monitors the change in stiffness as the design evolves. Changes to the geometry involve many attributes including the number of sipes, sipe depth, sipe location, block element edge taper, nonskid depth, area net‐to‐gross, and so forth. In this paper, two different formulations for calculating tread element or block stiffness are reviewed and are compared to finite element results in a few cases. A few simple examples a...

Surface Shape Optimization of Tire Pattern by Optimality Criteria

Abstract: A new optimization procedure to design the surface shape of tire patterns is proposed in which the optimality criteria is combined with finite element method. The effectiveness of this new procedure to control tread‐element contact pressure distribution was verified by building and testing the rubber block samples. The objective function was the pressure uniformity on the block and the constraint was to keep the contact area in the optimization process. The shape of the optimized surface was round at the edges and concave at the center where the pressure was large in the flat surface block. The pressure of the block with the optimized surface became uniform and the friction coefficient increased 10% on dry compared with the flat surface block. Furthermore, this procedure was applied to complicated block shapes such as tire patterns and it was verified that the optimized surface effectively improved vehicle handling, riding comfort and irregular wear.

Road Load Analysis

Abstract: Severe loading in a tire/suspension system arises when a rolling tire impacts an obstacle, such as a curb or pothole. Forces and moments at suspension hard points are needed during an impact for component specification, component durability, and endurance analysis. Today, automotive manufacturers and suppliers are promoting virtual prototyping by use of a computer‐aided engineering (CAE) tool. CAE consists of a tire model, a suspension model, and a solver for equilibrium equations. The tire models can be classified either by a parametric tire model (PTM) or by a finite element tire model. In the former tire model, tire stiffness is represented by a set of springs; tire forces and moments are estimated by Pajeka equations. This class of tire models is limited to modeling a vehicle's performance, such as ride and handling. In recent years, explicit dynamic modeling of a rolling tire impacting a road imperfection has been used to calculate forces transmitted to a suspension system. The tire model co...

Thermomechanics of Elastomers Undergoing Scission and Crosslinking at High Temperatures

Abstract: The elastomeric materials used in tires are frequently subjected to severe thermal, chemical, and mechanical stress conditions. These conditions produce significant changes in material properties that affect their service life. The prediction of service life has become an increasingly important part of the engineering design process, and there is a need for a robust life-prediction model. There are many physical factors that affect the durability of an elastomeric material, such as deformation, conversion of mechanical energy to heat arising from dissipative effects, heat transfer within the component, and changes in material properties because of changes in microstructure. The goal of this work is the development of a thermomechanics model that incorporates these factors. This study focuses on the effect of high temperatures on an elastomeric component. There are two sources of temperature increase, a hot environment and internal heating attributed to mechanical loading such as occurs during cyclic loading. Internal mechanical heating can lead to substantial temperatures occurring within the component. When the temperature of the material becomes sufficiently high, macromolecules undergo time-dependent scission, recoil, and may crosslink to form new networks with new reference confgurations. This process can affect the stiffness of the material system, induce anisotropy, and lead to permanent set. A constitutive theory is presented that accounts for this temperature-dependent microstruc- tural change on the mechanical response. It is based on experimental results and is motivated by the two-network theory of Tobolsky. The theory is applicable for large deformation and varying temperature histories. An example is presented that illustrates the implications of scission and re-crosslinking.

Application of a Shell‐Spring Model for the Optimization of Radial Tire Contour Using a Genetic Algorithm

Abstract: Optimization gives a new facet to design and development of tires. A new approach to the tire profile optimization is proposed in this study. The optimization procedure is integrated with a simple shell‐spring finite element model for faster evaluation. In the shell‐spring model, the shell elements represent the tire carcass, whereas the tread is represented by the spring elements. This is applied for the optimization of the tire contour for better maneuverability. The genetic algorithm, an evolutionary optimization procedure that is robust and efficient in solving complex optimization problems, is chosen. A new tire contour is obtained that improves tire maneuverability by increasing the sidewall belt tension.

Obstacle Impact Simulation of an ATV Using an Efficient Tire Model

Abstract: When a vehicle travels over a large obstacle at a significant speed, dynamic loads are created that are severe enough to cause damage to its components. Prediction of these impact loads early in the design can greatly aid the vehicle development process. Thus, automobile manufactures have devoted considerable effort developing computer models to simulate durability events. An important part of any durability simulation is the tire model. This paper focuses on the problem of efficiently predicting dynamic loads that occur when an all terrain vehicle (ATV) impacts obstacle impact. An ATV simulation model that uses an efficient and simple tire model to represent the enveloping behavior and dynamic response was developed with the AUTOSIM multibody dynamics program. This program, using Kane's Method and symbolic algebra to automatically generate fully parametric simulations that are both efficient and easy to use, was used to model both the tire and ATV rigid body dynamics. This paper describes the co...

BAT Model Lateral Parameters Characterization Using Finite Element Model

Abstract: The bushing analogy tire (BAT) model has been shown to be capable of modeling tire dynamics in vehicle dynamic simulations. In a recent paper, the tire and vehicle data have been used to demonstrate that the BAT model yields reasonable predictions of the vehicle vertical suspension dynamic responses up to the tire 2nd vertical mode (∼90 Hz). This paper studies the modeling of the tire dynamics in the lateral direction as the next step toward completion of the BAT model as a consistent 3‐dimensional tire dynamics model. Finite element (FE) analysis is an advanced analytical method for engineering analysis and has been accepted as the standard analytical tool for tires in the automotive industry. The tire data generated with FE models are also repeatable, without the data noise contained in physically measured laboratory tire data. FE models are also ideal for tire modeling studies because they enable the analysts to precisely control the modeling parameters. A tire FE model is, therefore, used her...

Tread Discontinuities as Source of Vibration/Noise — Transient Dynamics of Rolling Tire

Abstract: Tire vibrations supply energy for noise generation. Tread band features, such as grooves and blade cuts, affect noise signatures since they impart vibrations to a rolling tire. Finite element transient dynamics simulations have been performed with ABAQUS/Explicit on a rolling passenger tire to examine the vibrations induced by the entrance of tread pattern discontinuities into the contact patch. The loaded tire rolls on a 3.05 m (10 ft) diameter drum at terminal speeds of 4.3 km/h (2.7 mph) and 34.4 km/h (21.4 mph). Three models with augmented discontinuities in the circumferential ribs have been examined: 1) continuous (control); 2) angled lateral grooves; and 3) transverse grooves. They are ordered in increasing severity of rib discontinuity. The induced rolling vibrations are evaluated by identifying the ‘perturbed’ dynamic responses of (2) and (3) from (1). The results indicate that any discontinuity or abruptness in tread patterns can induce vibrations, which are similar in nature, for the t...