【作者】 张华俊；

【导师】 朱茂桃；

【作者基本信息】 江苏大学 ， 车辆工程， 2003， 硕士

【摘要】 钢板弹簧是汽车非独立悬挂装置中的一种常用的弹性元件，其强度特性和疲劳特性对车辆行驶的可靠性和安全性有重要意义。本文从对钢板弹簧结构应力的有限元分析基础上，利用S-N曲线法计算其循环载荷下的疲劳寿命， 使用参数化建模方法，建立钢板弹簧自由状态下的有限元模型。在两簧片的接触区域生成ANSYS软件所提供的接触单元，并通过适当的特性选取，来模拟簧片间的非线性接触。模拟装配夹紧过程施加载荷约束，并计算该过程中钢板弹簧内部产生的预应力。根据装配阶段各簧片的变形情况，并利用装配阶段所建模型的参数化语言程序建立钢板弹簧总成的有限元模型。使用加载头和簧片的接触行为来模拟加载状况，并将对簧片中心的变形控制转换为对加载点的位移约束，然后利用载荷步选项配置完成一个载荷循环，由此计算出加载阶段下钢板弹簧内部的应力循环。利用模型结果计算钢板弹簧的刚度，并进行钢板弹簧刚度试验验证模型的正确性。 通过外部文件完成装配阶段向加载阶段跨模型的应力结果数据的传递，然后在加载阶段模型中进行两阶段模型应力数据的合成运算，得到钢板弹簧实际工况下的完整应力循环。利用材料S—N曲线，并考虑钢板弹簧实际的零部件特征对其疲劳特性的影响，利用ANSYS参数化设计语言，编制程序计算出模型危险区域的疲劳寿命，并通过实际的钢板弹簧的疲劳试验来验证结论的正确性。 本文通过使用有限元法的结构应力分析计算和疲劳试验研究表明，钢板弹簧簧片间良好的摩擦状况对结构的应力分布无明显影响。同时通过使用各阶段应力合成的方法，能较好的模拟考虑钢板弹簧装配阶段预应力在内的完整应力循环。并且采用加载头和簧片间的接触行为能较准确的模拟出加载点存在着滑移状况的这种特殊的加载形式。最后对模型采用疲劳寿命的S-N曲线法计算能较准确的预测出疲劳破坏发生的区域及结构的疲劳寿命，在实际应用中对钢板弹簧的设计有重要的指导意义。更多还原

【Abstract】 Leaf spring is an elastic component often used in dependent-type suspension on modern vehicles, and its stress and fatigue strength characteristics are vital to the reliability and security in the vehicle riding. Based on the structure stress status research of leaf springs, this paper calculates the fatigue life of the leaf spring under cycle loading. And find out a solution to predict the fatigue life by combine FE analysis with program calculation.FEA model of its free status has been built using ANSYS APDL. To figure out the nonlinear contact condition of the leaf spring, we use contact element type to simulate the contact region of leaf spring, and treat with the elements’ attributes properly. Then the initial stress was calculated with proper load and the assembly process simulation. The FEA assembly model was built according to the distortion of the leaf spring in the former phase in ANSYS APDL. The load case was simulated with contact of loading head and leaf spring. And the displacement control of the leaf spring center was transferred to the displacement at load point. Then after the load step options configuration, the leaf spring stress circulation under cycle loadings was calculated. The model was validated by the result compare between the rigid extracted from the simulation results and the one out of the rigid test of the leaf spring.The stress result of assembly process and loading process was exchanged with the ANSYS special function on external data file. And the stress of leaf spring under virtual condition was calculated by the operation of array vectors of model results, which were generated from the external data file.Using the S-N curve, and considering the influence on fatigue characteristics of the leaf spring real feature, we edited the calculationprogram in ANSYS postprocessor to calculate the fatigue life on the critical points of leaf spring. At last the result’s validation was proven by the fatigue test of leaf spring.The results of the test and simulation reveal that based on the FE analysis, it is feasible to predict the fatigue life of the structure in the critical location when the S-N curve of the fatigue life applied. The meanings and conclusions can effectively instruct the design of leaf spring system.The results of the test and simulation reveal that based on the FEanalysis, the fine friction between leaves is no obvious influence upon the structure stress distribution. It can simulate the complete stress cycle including the initial stress in the assembly process, by composing stresses of two stages. Because of the sliding at the loading node, this special loading condition can be simulated by contact between the loading head and leaf spring. It is feasible to predict the fatigue life of the structure in the critical location when the S-N curve of the fatigue life applied. The meanings and conclusions can effectively instruct the design of leaf spring system.更多还原