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Premature Fatigue Failure Analysis of Axle in Permanent Magnet Direct-Drive Electric Locomotive
An-Xia Pan 1,2, Chao Wen 3,4,5, Haoyu Wang1, Peng Shi 1, Quanchang Bi1, Xicheng Jia1, Ping Tao1,2,*, Xuedong Liu1,2, Yi Gong6, Zhen-GuoYang6
1School of Mechanical Engineering and Rail Transit, Changzhou University, Changzhou 213164, China;
2Jiangsu Key Laboratory of Green Process Equipment, Changzhou University, Changzhou 213164, China
3Institute of Materials Modification and Modelling, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
4Shanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240, China
5CRRCQishuyan Institute Co., Ltd., Changzhou 213011, China
6Department of Materials Science, Fudan Unidan University, Shanghai 200433, China
Abstract：
This study investigates premature fatigue failures in three EA1N steel axles from perma-nent magnet direct-drive locomotives during wheel-seat bending tests. Complete fractureoccurred in one axle at 3 million cycles, and in the other two axles, cracks appeared andwere observed through magnetic particle detection at 3.5 million and 1.6 million cycles,respectively. A comprehensive failure analysis was conducted through metallurgical exam-ination, fractography, mechanical testing, residual stress measurement, and finite elementanalysis. The fractographic results revealed fractures consistently initiated at the wheel-seatto axle-body transition arc, exhibiting characteristic ratchet marks and beach patterns.The premature fracture mechanism was identified as a high-stress fatigue fracture. Theresidual stress measurements showed detrimental tensile stresses at the surface. Coupledwith the operating stress, the stress on the axle exceeds fatigue strength, which acceleratesthe initiation and propagation of fatigue cracks. Based on these observations, the failuremechanism was identified, and preventive methods were proposed to reduce the risk ofrecurrence of the in-service axles.
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