Modeling Transient Rolling Resistance of Tires3
The transient rolling resistance of several tires is predicted from the behavior of each tire on an equilibrium test. The objective of the study was to determine if model predictions would fall within the lab-to-lab experimental error described in the J-2452 test standard. The model used for this study, to predict the results of J-2452 from J-1269 data, was presented in Ref. [1]. The study used data from one tire to establish the model parameters. Then those parameters were used with tire and rolling resistance measurements from 12 other tires of another size. These tires were from four samples of each of three different tire constructions (tread patterns) and manufacturer. The reasons for the differences between the predictions and the test results were investigated and two significant sources of error were identified. First, the simplistic assumption that one set of heat-transfer parameters would apply to all tires was found to be inadequate. Second, the matrix of test conditions and regression model in J-1269, which must be used to extrapolate to the test conditions of J-2452, is inadequate. The modeling work in this article also found some of the details of the test protocols that may have significant effects on reported rolling resistance.Abstract
“First Tire” test data and model results. Model parameters at default values; two test sequences. (a) Full coastdown with five steps of load and inflation pressure, including tare. (b) Expanded and overlapping view of last non-tare step.
“First Tire” test data and model results (heat-transfer coefficient varied from default value, H0=40). (a) Full coastdown with five steps of load and inflation pressure, including tare. (b) Expanded and overlapping view of last loading step.
“First Tire” test data and model results (heat-transfer coefficient exponent varied from default value, Px=0.5). (a) Full coastdown with five steps of load and inflation pressure, including tare. (b) Expanded and overlapping view of last loading step.
“First Tire” test data and model results [velocity exponent (VSx) varied from default value, SF=1]. (a) Full coastdown with five steps of load and inflation pressure, including tare. (b) Expanded and overlapping view of last loading step.
Simulation and test data for 12 tires (h0=40, p=0.5, SF=1, for all simulations). Squares are experimental test values and diamonds are matching simulation model values. (a) Group A tires. (b) Group B tires. (c) Group C tires.
Analysis of paired values, test data minus simulation.
Model error measures for 12 tires: (a) standard deviation versus difference and (b) RMS difference versus difference.
Standard deviation per step for each tire.
Simulations with regression equations from Table 4.