Development of a Non-Pneumatic Wheel

Abstract

The pneumatic tire has proven to be the dominant design for rolling transport since shortly after its invention by John Boyd Dunlop in 1888. This paper identifies four critical characteristics that led to the success of the pneumatic tire: low energy loss on rough surfaces, low vertical stiffness, low contact pressure, and low mass. A non-pneumatic structure is proposed that exhibits these four critical characteristics while breaking some of the most restrictive design constraints imposed by pneumatic mechanics. This structure consists of a circular beam composed of two inextensible membranes separated by a relatively low modulus elastic material. The beam is connected to a hub by thin elastic spokes. This structure forming an integrated tire∕wheel is called a Tweel™.

Bioinspired engineering of honeycomb structure – Using nature to inspire human innovation

“…Besides, several tire engineers also attempted to develop non-pneumatic tires (NPT) through using polygon typed lattice spokes to replace the pneumatic tire (Fig. 19B) [212,213]. Kim et al [214] explored the structural performance of a NPT with 3D lattice spokes by performing numerical simulation of the contact pressure on the NPT and found that 3D hexagonal cellular spokes have a higher out-of-plane stiffness than 2D spokes under targeted load and a lower mass.…”

Metamaterial topology optimization of nonpneumatic tires with stress and buckling constraints

“…(Nondimensional or unit elastic properties are usually also applied, ie, E 0 =1, for traditional metamaterial design.) Hence, there is a close relationship between the compliance and the effective shear modulus . If the starting structure is uniform (say all elements at ρ=0.6) that the optimizer will not create a “SIMP‐convergent” design, ie, it will tend to a design with all densities at similar values—not black and white .…”

“…Idealized contact section of the nonpneumatic tire: deformed in red and undeformed in blue (adapted from Rhyne and Cron)…”

“…The critical characteristics of a pneumatic tire are low-energy loss from obstacle impacts, low mass, low stiffness, and low contact pressure. 1 These characteristics are coupled to certain design features in the pneumatic tire. This constrains the design (or application) of pneumatic tires.…”

“…The spokes in the region of the ground contact patch deforms (buckles) such that the tension in the opposite side spokes increase to carry the vehicle weight. As per the notation of Rhyne and Cron, the NPT is a “top loader” (different from a “bottom loader,” eg, a wagon wheel).…”