Search Results

A non-pneumatic tire (NPT) has two advantages over a conventional pneumatic tire; it is flat proof and maintenance free of air-pressure. In this study, while determining other advantages inherent in NPTs, the static contact behavior of NPTs with hexagonal honeycombs is investigated as a function of vertical loading and is compared with that of a pneumatic tire. A finite element based numerical simulation is carried out on the contact pressure of NPTs with cellular spokes and the local deformation of cellular spokes. A commercial finite element code, ABAQUS, is used to vary the vertical forces and lattice spoke geometries. A lower contact pressure is obtained with the NPTs than with the pneumatic tire due to the decreasing spoke stiffness of the NPTs when they are designed to have the same load carrying capability.

To facilitate the design of a non-pneumatic tire for NASA's new Moon mission, the authors used the Finite Element Method (FEM) to investigate the interaction between soil and non-pneumatic tire made of different cellular shear bands. Cellular shear bands, made of an aluminum alloy (AL7075-T6), are designed to have the same effective shear modulus of 6.5E+6 Pa, which is the shear modulus of an elastomer. The Lebanon sand of New Hampshire is used in the model. This sand has a complete set of material properties in the literature and Drucker-Prager/Cap plasticity constitutive law with hardening is employed to model the sand. The tires are treated as deformable bodies, and the authors used the penalty contact algorithm to model the tangential behavior of the contact. The friction between tire and sand is considered by using Coulomb's law. Numerical results show deformation of sand and tire.

Due to the relatively high freedom of selection of materials associated with a simple manufacturing method, a nonpneumatic tire (NPT) can be manufactured with a low viscoelastic energy loss material. A highly increasing demand to reduce greenhouse gases drives engineers to explore NPTs. NPTs consisting of flexible spokes and the shear band are still at an early stage of research and development. An optimization study of NPTs' geometry needs to be conducted, which is the objective of this paper. Parametric studies and design of experiments (DOE) of an NPT are conducted with a hyper-viscoelastic finite element (FE) model to determine the effects of three design variables on rolling resistance: the thickness of cellular spokes, the cell angle, and the shear band thickness. Considering vehicle load carrying capacity and riding comfort, ranges of vertical deflection between 18 and 20mm and contact pressure between 0.6 and 0.8MPa are selected as constraints for the optimization.