Viscoelastic Material Calibration Procedure for Rolling Resistance Calculation

As tire engineers, the authors are interested in predicting rolling resistance using tools such as numerical simulation and tests. When a car is driven along, its tires are subjected to repeated deformation, leading to energy dissipation as heat. Each point of a loaded tire is deformed as it completes a revolution. Most energy dissipation comes from the cyclic loading of the tire, which causes the rolling resistance in addition to the friction force in the contact patch between the tire and road. Rolling resistance mainly depends on the viscoelastic energy dissipation of the rubber materials used to manufacture the tires. To obtain an accurate amount of dissipated energy, a good understanding of the material mathematical model and its behavior is mandatory. For this reason, a calibration procedure was developed. To obtain a good method for calculating rolling resistance, it is necessary to calibrate all rubber compounds of the tire at different temperatures and strain frequencies. Thus, to validate the calibration procedure, simulations were performed to evaluate the error between the tests and models at material sample and tire levels. For implementation of the calibration procedure in the finite element models of rolling tires, a procedure is briefly described that takes into account the change in properties caused by the temperature during the simulations. Linear viscoelasticity is used to model the properties of the materials and is found to be a suitable approach to tackle energy dissipation due to hysteresis for rolling resistance calculation.