Potential advantage of thin-ply on the composite bolster of a bogie for a high-speed electric multiple unit

The application of composite materials in bogies for high-speed electric multiple units (EMUs) has been regarded as a technical breakthrough. The application of composite materials in rail vehicles began late in China. Currently, most composite materials are used in non-load-bearing components on the track, and applications in bogies, tie beams, and other load-bearing components are not mature. In this paper, we innovatively apply a design strategy using thin-ply on the composite bolster of a bogie for a multiple unit to optimize the static strength of the composite structure under very complex loading. We applied nine unconventional loads and 11 major operating loads in total to evaluate a potential positive influence of using thin-ply on the static strength of the composite bolster of a bogie. The numerical results showed that for all the complex loading scenarios, the application of thin-ply could effectively improve the static strength of the composite structure, which is more effective at the location of the bolts and holes. The research results break through the traditional design ideas of composite structures and provide an effective ply design and optimization strategy for composite structure design engineering of high-speed EMU.