Abstract: In order to solve the problem of insufficient strength in the design of a new type of commercial vehicle's step tube beam and achieve the goal of structural lightweight, a finite element model of the step tube beam is established and strength analysis is conducted. Due to the insufficient rigidity of the step, the structural strength and deformation displacement do not meet the reliability design requirements, and improvements need to be improved. Therefore, a new structural optimization method is proposed, which takes the total mass of the structure as the design objective and performs multi-objective optimization of size sensitivity under comprehensive strength conditions. The optimized step tube beam structure not only has good vibration characteristics, but also meets the reliability requirements for strength safety factors under various working conditions. The effectiveness of the simulation results and the feasibility of the lightweight scheme are confirmed through multi-axis coupled vibration durability tests, which solves the problem of insufficient strength of the commercial vehicle's step tube beam and meets the structural lightweight goal. This paper summarizes experimental test data and provides a loading verification method for simulating the strength reliability of step tube beams, which provides a reference for the structural design of similar step tube beams.

Key words: Step tube beam; Lightweight; Reliability; Multi-objective optimization

摘要： 为解决某新型商用车踏步管梁设计强度不足的问题并实现结构轻量化目标，建立了踏 步管梁的有限元模型，并进行强度分析。由于踏步的刚性不足导致结构强度及变形位移不满 足可靠性设计要求，需进行改进，因此提出一种新的结构优化方法，将结构总质量作为设计 目标，综合强度工况进行尺寸灵敏度多目标优化，优化后的踏步管梁结构不仅具有良好的振 动特性，且各工况下的强度安全系数均满足了可靠性要求。通过多轴耦合振动耐久试验证实 了仿真结果的有效性和轻量化方案的可行性，解决了该商用车踏步管梁强度不足的问题，同 时满足了结构轻量化目标。文章总结试验测试数据提供了一种用以仿真踏步管梁强度可靠性 的加载验证方式，为同类踏步管梁的结构设计提供了借鉴。

关键词: 踏步管梁；轻量化；可靠性；多目标优化