ASME-Based Structural Assessment of Head-Shell Junctions in Pressurized Railway Tank Wagons

This study presents an ASME-based structural assessment of the head-shell junction in a 60 m³ pressurized railway tank wagon subjected to an internal pressure of 0.45 MPa, combining classical shell theory with finite element analysis (FEA) in accordance with ASME Section VIII Division 2 stress categorization and linearization procedures. An analytical model based on the moment theory of shells of revolution was developed to describe displacement and rotation compatibility at the ellipsoidal head-cylindrical shell junction, allowing for the determination of contour interaction loads governing membrane-bending coupling in the discontinuity region. The calculated contour loads (Q₀ = 795 N/mm, M₀ = 13,350 N·mm/mm) indicate localized membrane-bending interactions caused by geometric discontinuity. Finite element simulations using axisymmetric (2D) and full 3D models were evaluated through the ASME VIII-2 stress linearization procedure, enabling comparison between analytical predictions and numerical results. The maximum equivalent stress according to the Coulomb-Tresca criterion reached 115 MPa (2D) and 117 MPa (3D), with less than 2% deviation, confirming the adequacy of the axisymmetric model. Stress linearization shows that the maximum combined primary membrane and bending stress (109.5 MPa) remains well below the ASME allowable limit of 308 MPa, while the discontinuity influence zone extends approximately 120-150 mm from the junction. The results confirm compliance with ASME VIII Division 2 requirements and demonstrate that the combined analytical-numerical approach provides a reliable method for evaluating stress concentration effects in railway tank wagons.