The SWIFT model is an extension of the MF-Tyre model developed by TNO and Delft University of Technology. This model, applicable up to 60 Hz longitudinal frequency, considers envelopment characteristics of the tyre. This paper presents the finite element analysis (FEA) approach to arrive at the 172 SWIFT model parameters. A 235/75R15 tyre is modelled using the commercial software package ABAQUS. The mixed Lagrangian-Eulerian approach has been used to simulate the loaded radius and contact length. Envelopment and cleat simulations are done with an explicit solver. The data curve fitted with MF Tool are found to be reasonable. This technique can be used to obtain SWIFT model parameters so that the vehicle dynamic behaviour of the tyre-vehicle combination can be virtually assessed before a real tyre is built; this will significantly reduce the tyre development time. © IMechE 2009.

Ramarathnam Krishna Kumar

Department of Engineering Design

Commercial software

CONTACT LENGTH

DELFT UNIVERSITY OF TECHNOLOGY

Development time

EULERIAN APPROACH

finite element analysis

Lagrangian

LOADED RADIUS

Model parameters

SWIFT MODEL

TYRE MODEL

VEHICLE DYNAMIC BEHAVIOUR

Vehicle dynamics

Parameter estimation

Vehicles

finite element method

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IIT Madras

A study on the estimation of SWIFT model parameters by finite element analysis

Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering

Pacejka's Magic Formula Tyre Model is widely used to represent force and moment characteristics in vehicle simulation studies meant to improve handling behaviour during steady-state cornering. The experimental technique required to determine this tyre model parameters is fairly involved and highly sophisticated. Also, total test facilities are not available in most countries. As force and moment characteristics are affected by tyre design attributes and tread patterns, manufacturing of separate tyres for each design alternative affects tyre development cycle time and economics significantly. The objective of this work is to identify the interactions among various tyre design attributes-cum-operating conditions and the Magic Formula coefficients. This objective is achieved by eliminating actual prototyping of tyres for various design alternatives as well as total experimentation on each tyre through simulation using finite element analysis. Mixed Lagrangian-Eulerian finite element technique, a specialized technique in ABAQUS, is used to simulate the steady-state cornering behaviour; it is also efficient and cost-effective. Predicted force and moment characteristics are represented as Magic Formula Tyre Model parameters through non-linear least-squares fit using MATLAB. Issues involved in the Magic Formula Tyre Model representation are also discussed. A detailed analysis is made to understand the influence of various design attributes and operating conditions on the Magic Formula parameters. Tread pattern, tread material properties, belt angle, inflation pressure, frictional behaviour at the tyre-road contact interface and their interactions are found to significantly influence vehicle-handling characteristics.

Vehicle System Dynamics

A study of the relationship between Magic Formula coefficients and tyre design attributes through finite element analysis

Journal	Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering
ISSN	09544070
Open Access	No