DESIGN AND FEA-BASED COMPARISON OF A NON-PNEUMATIC WHEEL (NPT) FOR ENHANCE COMFORT OF A WHEELCHAIRS

Abstract

The standard wheelchair design features two large rear wheels fixed parallel to the seat and two smaller, front swivel wheels. While functional, this configuration transmits terrain vibrations directly to the user, especially through the front wheels, which have limited shock absorption. For users with neuromuscular conditions, such vibrations can trigger spastic responses, reducing comfort and mobility.

This study explores the use of non-pneumatic tyres (NPTs) as a viable alternative to traditional wheels, focusing on structural performance and ergonomic improvements. A non-pneumatic front wheel, based on cellular structures, is proposed to mitigate vibrations from irregular terrain without relying on external damping systems. The goal is to increase comfort, enhance user stability, and maintain manoeuvrability.

To develop this solution, additive manufacturing techniques were applied using thermoplastic polyurethane (TPU) and polylactic acid (PLA) to fabricate the components. CAD tools and finite element analysis (FEA) were employed to evaluate mechanical performance metrics such as lateral load resistance, impact absorption, and structural integrity. Design optimisation focused on variables including material thickness, spoke inclination, and count, striking a balance between rigidity and flexibility.

The resulting prototype combines a rigid PLA rim with a flexible TPU tyre and spoke system. This configuration effectively absorbs shocks while preserving mechanical strength, reducing the need for complex suspension systems. In addition to improving the user experience, this design offers reduced production and maintenance costs. The findings support the feasibility of incorporating 3D-printed NPT wheels into conventional wheelchairs to improve accessibility and comfort