A flexible-spoke non-pneumatic tyre for manual wheelchairs

Abstract

This study combines laboratory testing with computer modelling to demonstrate, for the first time, the applicability of flexible-spoke non-pneumatic tyre (FS-NPT) technology in wheelchairs. Like existing solid non-pneumatic tyres, FS-NPTs are puncture-proof and will reduce the burden of tyre maintenance. Unlike existing solid tyres, FS-NPT performance is based on the properties of flexible structures (spokes), such as honeycombs, which can deform to offer superior cushioning and return to their original shape upon unloading. The results presented here indicate that the geometry of these spokes can be tuned to replicate the vertical stiffness of existing pneumatic tyres commonly used in wheelchairs while achieving higher rotational stiffness and reduced mass. Vertical stiffness is directly linked to user comfort while increased rotational stiffness is associated with increased wheeling efficiency. Results also indicate that FS-NPTs can change their stiffness to become softer under increased loading. This unique characteristic could enable the development of tyres that are relatively stiff during wheeling (for better wheeling efficiency), and softer during impact loads for better cushioning (e.g. during pavement dismount). The demonstrated capacity for stiffness tuning could enable personalising wheelchair tyres to meet the specific needs of individual users.