Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 Mar 2009

Accuracy, Sensitivity, and Correlation of FEA-Computed Coastdown Rolling Resistance3

and
Page Range: 4 – 31
DOI: 10.2346/1.3078466
Save
Download PDF

Abstract

This research deals with finite element analysis (FEA) predictions of coastdown rolling resistance as outlined by the SAE J2452 test procedure. The proposed method employs a phenomenological formulation of hysteresis which considers the effects of strain, strain rate, and temperature. Through specifically designed test conditions, material parameters are established for typical tire rubber components. The strain and strain rate histories at the cross section integration points are obtained from a static FEA of a loaded tire for one tire revolution and the desired speed. In subsequent postprocessing, the locations of the octahedral shear strain reversal in tire volume are found, and then rolling resistance is calculated by assuming an isothermal analysis. The simulation sensitivity to modeling considerations, including geometry accuracy and FE mesh resolution, on predicted rolling losses is pointed out. The applicability of the present approach to daily product engineering is discussed through benchmark studies of a variety of tires of different sizes, constructions, tread materials, and test conditions. Correlation studies demonstrate that this is a robust and easily implemented technique for rolling resistance analysis. A steady-state temperature solution, obtained from the hysteretic loss results, is used to predict the temperature field in the tire and to investigate its influence on the rolling resistance calculation.

Keywords: SAE J2452; coast down rolling resistance; hysteresis; FEA
Copyright: The Tire Society
FIG. 1.
FIG. 1.

Illustration of a typical setup in a drum rolling resistance test.

FIG. 2.
FIG. 2.

Typical rolling resistance results obtained in SAE J2452 test.

FIG. 3.
FIG. 3.

Calculated versus measured hysteresis on an Eplexor specimen of a high rolling resistance compound at test conditions from Table 1.

FIG. 4.
FIG. 4.

FE model building.

FIG. 5.
FIG. 5.

Strain and strain rate fields in a tread groove element along the streamline h(n) for the n-th integration point. 0° denotes the center of the footprint.

FIG. 6.
FIG. 6.

A close-up of the plot in Fig. 5 in the footprint zone.

FIG. 7.
FIG. 7.

Circumferential models used in this study: (a) default model, standard and cylindrical elements; (b) default model with standard elements only; (c) equally spaced 4° standard elements; (d) 2° in footprint, 4° in entry/exit zones, 8° outside, standard elements.

FIG. 8.
FIG. 8.

Correlation between predicted and measured rolling resistance at 15 and 115 km/h for all tires and all loads.

FIG. 9.
FIG. 9.

Correlation between predicted and measured rolling resistance, for all tires, loads, and speeds.

FIG. 10.
FIG. 10.

Temperature measuring points across the tire section.

FIG. 11.
FIG. 11.

Temperature in tire components during coastdown test of tire OE7-C at load of 4854 N (465 kgf) and inflation of 200 kPa.

FIG. 12.
FIG. 12.

Measured and calculated temperatures, tire OE1-A, at loads of 3354 N (324 kgf) and 4766 N (486 kgf) and inflation of 200 kPa.

FIG. 13.
FIG. 13.

Measured and calculated temperatures, tire OE7-C, at loads of 4854 N (465 kgf) and 6865 N (700 kgf) and inflation of 200 kPa.

  • Download PDF