A Finite-Strain Simulation of 3D Printed Airless Tires

The aim of this paper is to explore the mechanical characteristics of lattice-based airless tires made by three-dimensional (3D) printing technology under a large-deformation regime. The proposed airless tires are designed and fabricated based on the hexagonal lattice geometries under two different orientations. Experimental tests are conducted to investigate the effects of geometrical parameters and the types of lattices on the radial responses of airless tires. A finite-strain beam element is also established to simulate airless tires under various loading states, including radial, longitudinal, torsional, slipping, and rolling conditions. In this respect, a finite-element formulation is developed based on finite-strain hyperelasticity and solved by implementing an iterative Newton-Raphson scheme. Numerical and experimental results confirm that the proposed finite-strain beam element can be used for the analysis of airless tires with complicated lattice geometries under various nonlinearities, such as geometrical, material, and contact phenomenon. The numerical illustrations emphasize the effects of geometrical parameters of lattices and loading parameters on the behavior and mechanical properties of airless tires. The effects of lattice orientations, thickness, number of unit cells, and the coefficient of Coulomb friction between the tire and the ground, as well as loading direction, are investigated. Their implications on the responses of the airless tires with the same weight are highlighted, and pertinent conclusions are outlined. It is also shown that the proposed mathematical model can be used in future efforts for analysis, optimization, and design of lattice-based airless tires with complex geometries.