Structural analysis for the design of a lightweight composite railway axle

The unsprung masses associated with the axles of a railway vehicle result in costly impact damage to the rail infrastructure. A hybrid metallic-composite (HMC) railway axle is evaluated using finite element analysis. The axle mass is 74 kg, 63% lighter than an equivalent hollow steel axle. The HMC railway axle comprises a full length, carbon fibre reinforced, epoxy matrix composite tube with secondary overwrapping for stiffness and EA1N grade steel collars creating the wheel seats and journal surfaces. Maximum axle deflection is 1.72 mm with a misalignment at the journals of 0.21°, potentially requiring a bearing reassessment. Nominal bending stress in the axle is 99.3 MPa (Tsai-Wu damage index of 0.18). Peak bending and torsional stresses result in Tsai-Wu damage indexes of 0.71 and 0.42, respectively. The methodology in this paper can be extended to the design of future lightweight composite shafts to benefit many other industries.