Matsika, Emmanuel, O’Neill, Conor, Grasso, Marzio and De Iorio, Antonio (2018) Selection and ranking of the main beam geometry of a freight wagon for lightweighting. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit,

Traditional freight wagons employ I-beam sections as the main load bearing structures. The primary loads they carry are vertical (from loading units) and axial (from train traction and buffers). Ease of manufacturing has played an important role in selection of the I-beam for this role. However, with lightweighting increasingly becoming an important design objective an evaluation needs to be done to assess if there are other existing or new section profiles (geometry) that would carry the same operational loads but are lighter. This paper presents an evaluation of 24 section profiles for their ability take freight wagon operational loads. The profiles are divided into two categories, namely; “conventional made by wagon manufacturers (including the I-beam)” and “pre-fabricated” sections. For ranking purposes, the primary design objectives, or Key Performance Indicators (KPIs) were bending stress, associated deflection, and buckling load. Subsequently this was treated as a multi-criteria decision making process. The loading conditions were applied as prescribed by the EU standard EN 12663 – 2. To carry out structural analysis, Finite Element Analysis (FEA) was implemented using ANSYS software. To determine the validity of the FEA results, correlation analysis was done with respect to beam theory. Parameters considered were: maximum stress, deflection, second moment of area, thickness, bending stiffness and flexural rigidity. The paper discusses the impreciseness related to the use of beam theory since the local stiffness of the beam is neglected leading to an inaccurate estimation of the buckling load and the vertical displacement. Even more complicated can be the estimation of the maximum stress to be used for comparison when features such as spotwelds are present. The nominal stress values computed by means of Navier equation leads to

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