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Naturally Occurring Polymers—Plants
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
Bridgestone recently offered their version of an airless tire focusing on recyclability. Similar to the Tweel, the Bridgestone airless tire has a thin rubber tread supported by flexible thermoplastic spokes with an aluminum center.
Development of a novel spoke structure of non-pneumatic tires for skid-steer loaders using finite element analysis
Published in Mechanics Based Design of Structures and Machines, 2022
Ravivat Rugsaj, Chakrit Suvanjumrat
Non-pneumatic tire (NPT) or airless tire has recently been developed to replace traditional pneumatic tires. It has advantages in terms of its maintenance-free feature and superior durability over pneumatic tires (Cron, Rhyne, and Pompier 2006). NPTs consist of three main components: reinforced rubber shear bands, polymeric spokes, and metallic hubs. Usually, the polymeric spoke material is polyurethane (PU). It is a significant part that differentiates the NPT from the traditional pneumatic tires. Its unique function is to replace the internal air pressure for shock absorption and load-carrying capability. In addition, the combination of the polymeric spoke and shear band provides a uniform load distribution along the circumference of the tire. The difference in the spoke shape results in different vertical stiffness and riding of the NPT. Therefore, a polymeric spoke can be designed carefully to obtain desirable NPT characteristics (Jang et al. 2012; Rhyne and Cron 2006).
Study of geometric effects on nonpneumatic tire spoke structures using finite element method
Published in Mechanics Based Design of Structures and Machines, 2022
Ravivat Rugsaj, Chakrit Suvanjumrat
The nonpneumatic tire (NPT) or airless tire was developed in recent years to overcome disadvantages of traditional pneumatic tires, which can refer to (1) possibilities to cause harm or damage if they suddenly flatten while driving and (2) required maintenance for proper air pressure (Gent and Walter 2006). The general design of NPT can be described as a combination of an annular rubber shear band including the tread and polymer based spoke structure that is used to replace air pressure in the pneumatic tire (Rhyne and Cron 2006; Gasmi et al. 2012). The first commercial NPT was Tweel, which was developed and distributed by Michelin. The newly developed NPT can be designed to have uncoupled vertical stiffness and lateral stiffness properties, in which the former affects load carrying capacity and riding comfort, while the latter affects handling and cornering characteristics of the tire. Thus, the NPT’s vertical and lateral stiffness can be optimized independently, allow the designing of NPT to exceed pneumatic tires’ restriction and have wider range of design space depended on applications (Rhyne and Cron 2006). The modeling of NPTs is needed as the NPT designing process has proven to be complicated task and the required properties can be varied by a wide margin according to the applications. The deformation behavior of the NPT was found to be divided into three regions, which are the contact region, free surface region and support region. The three regions can be described as follows: (1) The contact region is where the band is supported by the ground contact patch, (2) the free surface region is where the spoke buckle freely, and (3) the support region is where the hub hanged by the spoke from the upper part of the band (Gasmi et al. 2012).