A numerical and experimental investigation into the force response of a tire impacting a large obstacle

Prediction of service loads for durability studies is an important application for vehicle dynamics simulation in the automotive industry. However, uncertainties in the tire models quite often produce doubts about the accuracy of loads yielded by these simulations. This uncertainty is a consequence of the difficulty associated with the process of modeling contact between the tire and an obstacle.; This dissertation examines the problem of modeling loads at the spindle that result from a tire impacting large obstacles. First, the importance that sidewall bulging has on the tire loads during large deformations is demonstrated. Then, an inflated elastic arch is used to approximate the sidewall bulging during large deformations. This concept together with a beam element is used to formulate a 2 dimensional finite element that represents a complete tire cross-section in an efficient manner. This element is then used to construct a two dimensional computer model of a tire for the purpose of predicting spindle loads during large deformations.; The tire model is first validated for the case of a tire undergoing large quasi-static deformations. The model is shown to compare well to experimental results (a tire loaded against a flat plate, and for a tire slowly rolling over large stepped obstacles).; The natural frequencies and mode shaped predicted by the tire model were then compared to the output from a detailed (and validated) tire finite element model. Two types of boundary conditions were examined: a tire with a fixed hub, and a tire contacting a surface. Good agreement was demonstrated between the models for the first six vibration modes for both types of boundary conditions.; Finally, the model validated for the case of a tire impacting a stepped obstacle at high speeds. The spindle forces generated by the model were shown to compare well to experimental results (a tire impacting a step on a rotating drum).