PSI - Issue 68

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 68 (2025) 929–935

European Conference on Fracture 2024 Effect of design optimization and material selection on the fatigue performance and fracture mechanism of a crank arm Shahriar Afkhami a *, Kalle Lipiäinen a , Erin Komi b , Tero Pesonen a , Masoud Moshtaghi a a LUT University, Laboratory of Steel Structures, 53850 Lappeenranta, Finland b Etteplan, Hyvinkää, Uusimaa, Finland Abstract The nature of additive manufacturing techniques enables them to fabricate complex designs with intricate features that are not feasible to produce via traditional ways. However, such changes in the original designs can alter the stress flow throughout the components and their mechanical performance; such issues can impose limitations against the feasibility of design optimization via additive manufacturing and must be considered doing so. This study investigates the design optimization of a high-performance bicycle crank arm fabricated by additive manufacturing using the laser powder-bed fusion technique (L-PBF). The main aim of the optimization was to decrease the overall weight of the component while maintaining its fatigue performance. Further, increasing the strength-to-weight ratio of the crank arm by decreasing the unit length of its material was considered in this research by changing the L-PBF’s raw material from stainless steel 316L to lighter alloys, i.e., Al5X1 aluminum alloy and Ti64 titanium alloy. Finally, each alloy’s defect distribution (including porosities and lack of fusions), microstructure, and fractography analysis were considered to establish a correlation between each material’s characteristics and its performance as an engineering component under cyclic loads. The results indicated successful design optimization using 316L and Ti64 alloys as raw materials for additive manufacturing; however, components made of the aluminum alloy had comparably inferior fatigue performance. Such discrepancies in fatigue performance can be attributed to their different defect distributions and surface quality features. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers Keywords: additive manufacturing; design optimization; fatigue; aluminum; titanium © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers

*Corresponding author. E-mail address: shahriar.afkhami@lut.fi

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers 10.1016/j.prostr.2025.06.152