en Rolling Stock Rolling Stock پژوهشي Research <div style="text-align: justify;"><span lang="PT-BR" style="font-size:10.0pt"><span style="line-height:115%"><span style="font-family:&quot;Times New Roman&quot;,serif">Railway axles are safety-critical components whose structural integrity is paramount, especially under dynamic loads encountered during curve negotiation,</span></span></span> <span lang="PT-BR" style="font-size:10.0pt"><span style="line-height:115%"><span style="font-family:&quot;Times New Roman&quot;,serif">where fatigue cracking often initiates at press-fitted components. This study presents a comparative stress analysis of the axles in two widely used freight bogies, the Y25 and the 18-100, while traversing curved tracks. A combined simulation methodology was employed: dynamic forces were first extracted using Multibody Dynamics (MBD) analysis in Universal Mechanism (UM) software. These forces were then applied to detailed finite element models of the axles, developed in CATIA and analyzed in Abaqus, to determine the stress distributions. The analysis was performed for curve radii of 400 m and 1000 m at speeds of 72, 90, and 108 km/h. Results indicate that the maximum von Mises stress occurs at the fillet region between the axle journal and the wheel seat (Section A), predominantly on the outer axle. The 18-100 bogie axle experienced a higher maximum stress (357.57 MPa) compared to the Y25 bogie axle (248.33 MPa) under the most critical condition (400 m curve at 108 km/h). Stress magnitudes increased significantly with speed on sharper curves, highlighting the critical influence of operational parameters. The findings provide valuable insights for bogie selection, maintenance planning, and future design optimizations, such as the potential use of composite materials to reduce weight and mitigate fatigue.</span></span></span></div> Stress Analysis, Railway Axle, Freight Bogie, Y25 Bogie, 18-100 Bogie, Curve Negotiation, Finite Element Analysis (FEA), Multi-Body Dynamics (MBD). 37 51 http://ijrare.iust.ac.ir/browse.php?a_code=A-10-371-1&slc_lang=en&sid=1 Seyed mohammad reza Mousavi se.mohammadreza.mousavi@gmail.com 180031947532846003026 180031947532846003026 No School of Railway Engineering, Iran University of Science and Technology, Tehran, Iran Amin Owhadi aohadi@iust.ac.ir 180031947532846003027 180031947532846003027 Yes School of Railway Engineering, Iran University of Science and Technology, Tehran, Iran Majid Shahravi m_shahravi@iust.ac.ir 180031947532846003028 180031947532846003028 No School of Railway Engineering, Iran University of Science and Technology, Tehran, Iran