基于模糊理论的车辆变刚度弹簧组可靠性优化设计

为提高变刚度弹簧组的设计质量，在传统优化设计方法的基础上，应用模糊设计理论和可靠性设计理论，建立了当弹簧应力和强度分别为随机变量和模糊变量时，综合考虑静强度、疲劳强度、稳定性、质量等因素的变刚度弹簧组的模糊可靠性优化设计模型.以货车某新型变刚度弹簧组为研究对象，利用建立的模型对其进行了优化设计分析，计算结果显示，空重车静挠度分别比原设计方案提高了5.4和3.2 mm，同时还使其总质量降低了约15.8%，表明所建立的模糊可靠性优化设计模型能满足设计要求. 

Reliability Optimization Design of Vehicle Variable Stiffness Spring Assembly by Fuzzy Theory

In order to improve the design quality of spring assembly, a fuzzy reliability optimization design model of variable stiffness spring assembly was established using the fuzzy and the reliability design theory based on traditional optimization design method. In this model, the spring stress and strength were used as a random variable and a fuzzy variable, respectively; and the static strength, fatigue strength, stability, and quality factors were synthetically considered. In addition, taking a new type of variable stiffness spring assembly of a freight car as the object, an optimization analysis was carried out by used of the proposed model. The calculation results show that compared with the original design program, the model increases the static deflection of vehicle in empty and heavy load 5.4 and 3.2 mm, respectively; and in the mean time decreases the total quality of the spring assembly by about 15.8%. Therefore, the fuzzy reliability optimization design model can meet the design requirements.