Design of A Lightweight Multifunctional Composite Railway Axle Utilising Coaxial Skins

Abstract

The potential for lightweighting of railway axles was investigated to primarily reduce the unsprung mass of rail vehicles. The reduction of unsprung mass equates to an overall lighter train which will help to reduce: track damage, energy consumption and total operating costs. This paper presents the design of a lightweight multifunctional hybrid metallic-composite railway axle utilising coaxial skins. The lightweight axle assembly comprises a carbon fibre reinforced polymer composite tube with steel stub axles bonded into either end. The structural hybrid metallic-composite railway axle is surrounded by coaxial skins each performing a specific function to meet secondary requirements. These include fire and ballast skins to protect the axle core. An outer pigmented layer provides visual identification of the axle class, along with protection against environmental agents. Integrated into the railway axle is a structural health monitoring layer to provide feedback on the integrity of the composite tube and adhesive bonds during the operating life. A tether assembly acts as a failsafe against wheel detachment resulting from catastrophic axle damage. The optimised hybrid metallic-composite railway axle design concept has a mass of 200 kg representing a reduction of 50% over the solid steel version.

A vision for a lightweight railway wheelset of the future

“…Another approach includes a fixed (not bonded to the axle) external shield. These layers could be integral with the axle structure as proposed by Mistry et al, 31 through the use of coaxial skins around a HMC railway axle to meet secondary functional requirements.…”