To achieve both lightweight construction and improved ride comfort in railway vehicles, it is essential to provide a method that allows even less-experienced designers to intuitively identify directions for structural modification and solution analysis obtained from machine learning. This study proposes a method for calculating circumferential out-of-plane bending moments in carbody shells made of aluminum hollow extrusions, based on beam theory using surface sheet axial forces discretized at the intersections of ribs and surface sheets. The validity of the method was verified using a simplified cantilever model subjected to vertical and moment loads, showing good agreement with theoretical solutions and a maximum difference of less than 1%. The method was applied to a structure, and the resulting structural moment distributions were compared with deformation modes at five cross-sections. The trends of out-of-plane deformation and structural moment distribution, as well as the relative magnitudes among sections, were consistent. These results demonstrate that the proposed method is sufficiently practical for railway vehicle structural design.
Takeshi KAWASAKI (2025) studied this question.