Mechanical elastic wheel improving road holding and wear resistance of tire

Abstract: A non-pneumatic tire appears to have advantages over the conventional pneumatic tire in terms of flat proof and maintenance free. A mechanical elastic wheel with a non-pneumatic elastic outer ring which functions as the air of the pneumatic tire was presented to reduce the risk of puncturing the conventional pneumatic tire and to enhance the grip performance. The mechanical elastic wheel structure was non-pneumatic integrated configuration which was flat proof and maintenance free of air-pressure. In this study, the static contact behavior of mechanical elastic wheel was investigated as a function of vertical loading and was compared with that of a pneumatic tire. The special suspended hub loaders of mechanical elastic wheel were employed to reduce the contact stiffness and increase contact area so that a stable friction was obtained. An analytical model for a non-pneumatic mechanical elastic wheel on rigid ground is presented. The model consists of a thin flexible annular outer ring and hinge units that connect the outer ring to a rigid hub. According to the wheel structure characteristic and bearing way, outer ring uniformly curved beam model was established based on a circular Timoshenko beam that takes into account deformations due to bending, shearing and circumferential extension, and discrete spoke which was accounted for only in tension was modeled based on continuous spoke model. In addition, the finite element model of mechanical elastic wheel was modeled by using the commercial finite element software ANSYS. To establish the finite element model, various nonlinear factors, such as the geometrical nonlinearity, material nonlinearity and contact nonlinearity, were all considered. In order to proved the validity of the analytical model and the finite element model, load characteristic test of the mechanical elastic wheel was conducted by tyre dynamic test-bed to obtain load-deflection curve. The results of analytical model and three-dimensional nonlinear finite element model were validated by the load characteristic test of mechanical elastic wheel. The trend of tested results were consistent with simulation results and analytical results. The prototype experiment confirmed the analytic model and the finite element model rationality. Finite element methods were used to analyze the contact pressure distribution and grip performance in static loading. Simulation results show that the radial stiffness of mechanical elastic wheel is greater than that of pneumatic tire, so that mechanical elastic wheel could maintain more better roundness and lesser rolling resistance than pneumatic tire. Through mechanic analysis, it shows that radial stiffness of mechanical elastic wheel is determined by stiffness of elastic outer ring, stiffness of hinges and the suspended hub loaders. Besides that, simulation results also show that the static contact pressure of mechanical elastic wheel on tire shoulder becomes protuberant with the increase of the vertical load, and the static contact pressure of mechanical elastic wheel is more evenly than that of traditional pneumatic tire. That is because the suspended hub loaders could reduce the stress concentration of tire shoulder and enhance tire wear resistance and grip performance by controlling outer ring deformation. The results can provide guidance for experiment research, structural optimization and improvements of vehicle dynamics.