Abstract
The cast aluminum beam is a key structure for carrying the body-hung traction motor of a high-speed train; its fatigue property is fundamental for predicting the residual life and service mileage of the structure. To characterize the structural fatigue property, a finite element-based method is developed to compute the stress concentration factor, which is used to obtain the structural fatigue strength reduction factors. A full-scale fatigue test on the cast aluminum beam is designed and implemented for up to ten million cycles, and the corresponding finite element model of the beam is validated using the measured data of the gauges. The results show that the maximum stress concentration occurs at the fillet of the supporting seat, where the structural fatigue strength reduction factor is 2.45 and the calculated fatigue limit is 35.4 MPa. Moreover, no surface cracks are detected using the liquid penetrant test. Both the experimental and simulation results indicate that the cast aluminum beam can satisfy the service life requirements under the designed loading conditions.
Highlights
For a high-speed train (HST) equipped with bodyhung traction motors, cast aluminum beams are usually employed as the main load-bearing structures of the vehicle drive systems
This method considers that structures with the same stress concentration factor, material, and manufacturing process, have the same fatigue life provided the local stress spectra are equal
4.1 finite element (FE) Modelling The cast aluminum beam has a complex geometry, and several stiffener ribs are designed inside the hollow structure to enhance the bearing capacity
Summary
For a high-speed train (HST) equipped with bodyhung traction motors, cast aluminum beams are usually employed as the main load-bearing structures of the vehicle drive systems. To analyze the fatigue properties of such large and complex structures, the S–N curvebased nominal stress method is widely used in industrial applications. This method considers that structures with the same stress concentration factor, material, and manufacturing process, have the same fatigue life provided the local stress spectra are equal. The nominal stress method is simple to use because stresses can be calculated or tested from a certain structure or specimen It is suitable for the fatigue strength. The fatigue properties of materials obtained via benchmark specimens are insufficient to express those of a complex structure, which is determined simultaneously by the stress concentration, structural size, and manufacturing process [10]. A ten million cycle-fatigue test of a full-scale beam was carried out, and the potential surface cracks were examined using a liquid penetrant tes
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