Study on structural optimization of braid‐and‐lay integrated carbon fiber reinforced polymer for metro bogie

Carbon fiber reinforced polymer is an effective solution for replacing metal materials and achieving lightweight, and both three‐dimensional (3‐D) braided composites and prepreg laminated composites have their strengths and weaknesses. Using only one forming process can be challenging to meet the performance requirements of structural components under complex operating conditions. To effectively reduce the production cost and cycle time of large structural components while ensuring the mechanical properties of the structure, this article proposes a novel three‐dimensional braided and prepreg‐layered (braid‐and‐lay) composite forming process that is studied in the context of metro bogies. First, the performance advantages of braid‐and‐lay composites were verified through experimental methods. Then, a multi‐scale analysis method, combining experimental and finite element analysis, accurately predicted the macroscopic elastic parameters of the three‐dimensional braided composite with an error of less than 10% compared to the experimental values. Finally, a structural optimization design of the braid‐and‐lay composite metro bogie was carried out based on the predicted elastic parameters. The results show that the mass of the structure was reduced by 15.33%, from 272.103 to 230.386 kg, while ensuring that the displacement and stress responses do not exceed the constraint range.