转向机构的时变可靠性分析与综合

发布时间：2018-01-01 04:10

本文关键词：转向机构的时变可靠性分析与综合　出处：《西华大学》2012年硕士论文　论文类型：学位论文

【摘要】：在不确定性下研究机构时变运动可靠性问题是近年来机构学研究的热点课题之一。由于机构受几何尺寸、运动副间隙、工作原理及使用环境的影响，，其运动输出往往具有不确定性，从而可能引起机构运动精度可靠度下降、机构动作不可靠等问题。就机构运动精度可靠性而言，目前大多方法属于点可靠度分析方法，点可靠度只是提供了某一瞬时时间点上机构运动输出满足期望运动输出或实现预定功能的可能性。显然，从整个运动区间来考察机构的可靠性往往比点可靠性更加合理、更加符合实际。因此，在不确定性条件下研究机构的时变（区间）运动可靠性及其优化设计（综合）问题，具有极为重要的理论意义和实际价值。本文以整体式转向机构和齿轮齿条式转向机构为研究对象，在分析转向机构时变运动可靠性和优化综合的同时，对时变运动可靠性方法进行了详细的论述。本文主要研究工作可以概括如下： 1在对目前汽车中广泛使用的整体式转向机构和齿轮齿条式转向机构进行运动分析的基础上，综合考虑构件尺寸的不确定性（随机性）和机构自身结构误差，建立了转向机构误差概率模型。 2引入结构可靠性分析方法中上穿越率和下穿越率概念，并结合一次二阶矩法（FOSM）和首次穿越的Poisson近似方法推导出机构时变（区间）运动可靠度解析表达式。以此为基础建立了整体式转向机构和齿轮齿条式转向机构的时变运动可靠性模型。并通过相关算例将其与点可靠性进行比较分析，结果表明机构时变可靠度总是小于等于点可靠度，满足点可靠度并不意味着满足时变可靠度。显然，机构时变运动可靠性比传统的点可靠性更加合理，它以整个运动区间为考察对象，能够体现机构在整个运动过程中满足预期功能的可能性。 3针对机构优化设计（综合）问题，提出了机构时变运动可靠性优化综合方法。建立了整体式转向机构时变运动可靠性优化模型，通过数值实例将其与该机构的确定性优化方法及点可靠性优化方法进行比较分析。结果表明，机构时变运动可靠性优化方法比确定性优化方法和点可靠性优化方法更加优越，不仅可以在满足可靠性要求的同时减小机构的结构误差，而且其求得的优化解往往也比其余两种优化方法稳定。
[Abstract]:The reliability of time - varying kinematic reliability of the mechanism is one of the hot topics in recent years . As the mechanism is influenced by the geometric dimension , the motion sub - gap , the working principle and the use environment , the motion output of the mechanism tends to be uncertain . The main research work of this paper can be summarized as follows : Based on the motion analysis of the integral steering mechanism and the gear rack steering mechanism widely used in the current automobile , the uncertainty of the dimension of the components ( randomness ) and the structure error of the mechanism are comprehensively considered , and the steering mechanism error probability model is established . This paper introduces the concept of the upper crossing rate and the lower crossing rate in the structural reliability analysis method , and derives the analytic expression of the time - varying motion reliability of the mechanism time - varying ( interval ) based on the first - order moment method ( FOSM ) and the Poisson approximation method for the first pass . The results show that the time - varying reliability of the mechanism is always less than or equal to the reliability of the point . The results show that the time - varying reliability of the mechanism is always less than or equal to the reliability of the point . The optimization method of time - varying kinematic reliability of the mechanism is presented in this paper . The optimization model of time - varying motion reliability of the integral steering mechanism is established , and compared with the deterministic optimization method and the point reliability optimization method of the mechanism through numerical examples . The results show that the optimization method of the time - varying motion reliability of the mechanism is superior to the deterministic optimization method and the point reliability optimization method , and the structural error of the mechanism can be reduced while the reliability requirement is met , and the optimization solution obtained by the method is more stable than the other two optimization methods .

【学位授予单位】：西华大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH112;U463.4

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