Bu-Ali Sina UniversityJournal of Stress Analysis2588-25979220251201Presentation of a Proper Finite Element Model for Simulation of a Solid Oxide Fuel Cell at the Beginning of Operation (Warm-Up)111671510.22084/jrstan.2025.26616.1220ENMohammad HosseinGoudarzi KhouyganiDepartment of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran.MohsenEsfahanianDepartment of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran.HoseinHamidi RadDepartment of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran.Journal Article20220815In this study, we present a proper finite element model for the simulation of a single solid oxide fuel cell (SOFC) at the beginning of operation (warm-up). The SOFC comprises five layers: two ferrous base metal layers, one yttriastabilized zirconia (YSZ) electrolyte layer, one anode layer featuring a Ni/YSZ structure, and one cathode layer consisting of LSM. Our thermal-structural analysis considers crucial physical parameters, including the warm-up process, mechanical contact, and thermal contact. Zirconium oxide, renowned for its O<sub>2</sub>- conductivity at the operating temperature of the fuel cell (800 <sup><em>◦</em></sup>C), serves as the chosen base material. As the SOFC heats up, thermal stresses emerge among these layers. To investigate the fracture procedure during warm-up, the finite element method is employed, examining various parameters such as the presence of mechanical contact, warm-up conditions (radiation or isothermal), and thermal contact resistance. Simplifications commonly employed in the finite element method, such as solving fields independently or simultaneously and defining material properties as layered elements, are also considered. The analyses and calculations are conducted using the ANSYS software. Our primary objective is to present a refined model that minimizes error and analysis time. Various conditions are examined, including layer slip effects, the use of composite or layered elements, the simplification of layer properties, the impact of contact resistance, and the investigation of simultaneous and indirect analyses, assessing their validity through a series of analyses.Bu-Ali Sina UniversityJournal of Stress Analysis2588-25979220251201Experimental and Numerical Analysis of the Strain Distribution in a Three-Piece Bogie Bolster1321671610.22084/jrstan.2026.28556.1251ENAmir MasoudHamidi MajdDepartment of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran.Moein Industrial Group, Tehran, Iran.0009-0000-4892-8033Seyed EbrahimMoussavi TorshiziDepartment of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran.0000-0001-9312-4886JavadZareDepartment of Mechanical Engineering, Shiraz University of Technology, Shiraz, Iran.Journal Article20231116The bolster, a critical component in three-piece casting bogies, bears half of the wagon’s total weight. This study investigates the strain distribution of an optimized bolster through experimental testing. The optimized bolster is fabricated from a modified material exhibiting enhanced impact properties compared to conventional grades. Additionally, minor geometric refinements, such as a slight increase in the fillet radius at sharp edges and around holes, have been implemented to mitigate local stress concentrations. Strain measurements are acquired at 114 points on the bolster surface. A numerical model is developed and subsequently validated against these experimental results, enabling a detailed investigation of the bogie’s behavior and facilitating the proposal of new geometrical modifications. The discrepancy between the experimental and simulated results averaged approximately 10%, a margin considered acceptable. Throughout all measurement points, the strain remains within the elastic range, gradually returning to zero upon load removal. The calculated factor of safety for the bolster approximates 2. Ultimately, based on these findings, recommendations are provided for further modifications to<br>the bolster design, aimed at enhancing its factor of safety and potentially increasing its axle load capacity.Bu-Ali Sina UniversityJournal of Stress Analysis2588-25979220251201Stress Concentration and Fatigue Crack Propagation at the Fir-Tree Root of Gas Turbine Disks Caused by Interconnection Tube Failure between Blades2329671710.22084/jrstan.2026.29737.1262ENSeyed AhmadMortazaviDepartment of Applied Design, Faculty of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran.AbbasRahiDepartment of Applied Design, Faculty of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran.0000-0002-7123-1741Seyed MohammadJafariDepartment of Applied Design, Faculty of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran.Journal Article20240809Industrial gas turbine blades operate under severe thermo-mechanical conditions such as high temperature, corrosion, erosion, and cyclic loading, which make them highly prone to stress concentration and fatigue failure. This study investigates the failure mechanism of the interconnection tube connecting the first-stage blades of a gas turbine used in the oil industry. A combined experimental and numerical approach was employed, including hardness testing, chemical and structural analyses, visual inspection, macroand micro-fractography, and finite element modeling. Fractographic analysis revealed clear fatigue striations on the fracture surface of the interconnection tube, confirming a fatigue-induced failure initiated at corrosion pits and eroded regions. The finite element results showed severe stress concentration at the fir-tree root region of the turbine disk, coinciding with the actual fracture zone observed in the failed component. Failure of the interconnection tube increased the transmitted stress to adjacent blades and led to an approximately 22% reduction in the fatigue safety factor at the fir-tree root, as determined by Goodman diagram analysis. The strong correlation between numerical and experimental results confirms that stress concentration, combined with corrosion, erosion, and vibration effects, plays a dominant role in accelerating fatigue crack initiation and reducing the structural reliability of the rotor assembly.Bu-Ali Sina UniversityJournal of Stress Analysis2588-25979220251201Numerical Investigation and Comparison of Temperature and Residual Stress in FSW and UFSW Processes of Two Heterogeneous Aluminum Alloys3139671410.22084/jrstan.2026.32471.1281ENMaziarMahdipourDepartment of Mechanical Engineering, Kermanshah University of Technology, Kermanshah, Iran.0000-0001-8875-2968AmirGhiasvandDepartment of Mechanical Engineering, Tabriz University, Tabriz, Iran.0000-0001-5587-001XJournal Article20260421Friction stir welding (FSW) is classified as a solid-state joining method with no melting of the workpiece and tool. The affecting factors for creating a joint in this method are the generated heat, pressure, and large deformations in the workpiece. The generation and appropriate distribution of heat in the FSW process guarantee the creation of a high-quality and defect-free joint. One of the modifications that are used to adjust the temperature distribution to other zones of the workpiece is the usage of the Underwater Friction Stir Welding (UFSW) technique. In the present study, the FSW and UFSW processes have been numerically investigated using the indirect process simulation technique and the applied heat flux coding through the DFLUX subroutine, and the results of the temperature distribution and residual stress in the joined samples obtained using these two techniques have been compared. According to the results, it was found that the temperature distribution patterns in the FSW and UFSW processes differ significantly from each other, and these changes in the temperature distribution of the workpiece ultimately lead to a significant difference in the temperature pattern in the weld cross-section and the longitudinal and transverse residual stresses in the specimens joined by the two techniques.