PSI - Issue 53

Vítor M.G. Gomes et al. / Procedia Structural Integrity 53 (2024) 285–290

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Author name / Structural Integrity Procedia 00 (2023) 000–000

2.2. Repair of Components

In operation or even during the assembling process, rolling stock components such as wheel-set, gear seat, and axle bodies might be damaged causing surface defects such as scratches, and dents, among others (Zhengkai et al. (2023)). Ignoring the appearance of these defects will reduce the mechanical resistance of the component, and might cause an early failure than expected. In order to avoid the replacement of such large components, the reparation of the damaged surface can be made by additive processes. The Directed Energy Deposition technologies, DED, has been used for rapid reparation of components damaged locally (Saboori et. al. (2019); Piscopo (2022); Lewis et. al. (2019); Hua and Zhou (2022)). For example, an axle train with a notch was repaired with laser cladding in the laboratory, as illustrated in Fig. 4 - A. The axle specimen was tested posteriorly under fatigue rotating bending conditions, not exhibiting significant di ff erences in the resistance among non-clad and clad specimens. Another application is found in (Zhu et. al. (2019)), where laser cladding was applied to repair local defects on railway wheels (see Fig. 4 - B).

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Fig. 4. Laser cladding for reparation of: A - railway axle (TWI (2023)), B - railway wheel (Wila Laser Cladding Tech (2023)).

2.3. Development of New Design for Parts

https://www.twi-global.com/media-and- AM may be also employed in the development process of new designs of railway rolling stock parts. ALSTOM improved the design of anti-roll system support in train bogies by combining the topology optimization with selective laser melting, SLM, process reducing the weight by 70% (Alstom (2022)). Additionally, brake suspension links (see Fig. 5), secondary vertical damper seats, anti-snake damper seats, and lateral stops were also optimized in terms of weight and geometry permitting a weight reduction in 56, 72, and 27 %, respectively for the last three components (Zhengkai et al. (2023)). Due to the additive characteristics of the AM process, AM can be integrated with new computation methodolo gies in the manufacturing process, such as topological optimization and the development of components with lattice structures. Lattice structures along with topological optimization allow optimizing the weight of the components in order to maximize the the specific strength and specific sti ff ness. Structures such as aluminium honeycomb panels and sandwich panels are some examples of the lattice structures applied in high-speed train body floor and skirt plates (Guo (2022); Zhengkai et al. (2023)). In addition, additive manufacturing can be used in the production of molds. Accordingly Zhengkai et al. (2023), axle boxes produced from sand molds manufactured by AM allowed to reduce the production time in four times without a ff ecting the structural, geometrical and surface quality requirements.

2.4. A Future Perspective for AM in the Railway Rolling Stock

As presented in Fig. 1, the AM process may be applied in di ff erent applications, mainly in maintenance and new designs to increase the weight-strength ratio of the components. In accordance with presented in (Zhengkai et al.