Structural design and optimization of a guardrail for the train-to-train collision test platform

The guardrail structure is generally installed in parallel on the inner side of the basic rail, which is expected to prevent the wheelsets of rail vehicles from derailing during the train-to-train collision test. This study aims to conduct research on the structural design and optimization of the guardrail for the train-to-train collision test platform. A two-step optimization method was employed, i.e., the topological optimization design of the supporting post and the lightweight size optimization of the overall guardrail, to improve the material utilization rate and achieve the best space size design. In order to explore the topology optimization of the supporting post alone and the overall topology optimization of the guardrail (i.e., a combination of supporting post and central plate), two optimization models were designed with seven subcases each loaded with different heights (H_Fc). Through comparative analysis, the selected supporting post under the H_Fc of 650 mm exhibited a mass reduction rate of 69.597%. In order to explore the optimal configuration of the guardrail and the spacing arrangement of supporting posts, a lightweight size optimization design based on topological result was carried out. The supporting post condition and the central plate condition were considered according to the different positions where the guardrail may be impacted by the wheelset, and the normalization method was adopted to make the output responses dimensionless. The optimization results were obtained by implementing the Box Behnken method, the Hammersley method, response surface model and genetic algorithm. The optimized structure showed that its mass per unit length is 43.885% lighter than the initial configuration. Compared with the conceptual design, the optimized structure was 3.564% lighter, while the maximum deformation was reduced by 9.049%. Therefore, the lightweight optimized guardrail has higher protection strength and lower mass, which is expected to be widely used for the train-to-train collision test platform.