Integration of fatigue life assessment into structural optimization of a railway vehicle bogie frame: development and application of a new methodology

Abstract Rolling stock manufacturers are increasingly developing innovative structural solutions aimed at enhancing the quality and reliability of railway vehicle components, thereby enhancing the existing standard platforms. Structural optimization processes represent an effective strategy to reduce manufacturing costs by promoting geometries that are simpler to design and fabricate. While structural optimization is now a well-established practice in the railway sector, the integration of fatigue considerations into this process remains limited. Although several studies in the literature attempt to address fatigue through various approaches, none have proven entirely satisfactory. This research aims to bridge this gap by introducing a novel methodology capable of automatically computing fatigue-related parameters, thereby enabling a parallel fatigue performance evaluation throughout the entire optimization process, iteration by iteration. The methodology is implemented via a dedicated software tool, which can be adapted with minimal modifications to interface with most commercial finite element platforms. The proposed approach has been applied to the structural optimization of a metro bogie frame. The methodology was then employed in multiple activities: iterative fatigue monitoring during the optimization process; extension of a previous study by incorporating fatigue behavior; reconstruction of the final post-optimization geometry based on fatigue-driven design considerations, thus ensuring manufacturability and fatigue resistance. Although not all potential uses have been fully explored, the proposed methodology has demonstrated its effectiveness as a valuable tool for integrating fatigue into structural optimization, ultimately enabling the designer to reconstruct fatigue-aware final geometries.