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]:Research institutions under uncertainty time-varying reliability problem is one of the hot topic in research institutions in recent years. Because the institutions by the geometrical dimensions, clearances, affect the working principle and use of the environment, the output motion is uncertain, which may cause the motion precision reliability reduction, agency action is not reliable. The motion precision and reliability, most of the current methods belong to reliability analysis method, the reliability of only provides an instantaneous time mechanism motion output satisfies the desired output motion or the possibility of realizing a predetermined function. Obviously, the reliability from the entire movement range to examine the mechanism more often than reliability is more reasonable, more in line with the actual research institutions. Therefore, in conditions of uncertainty and time-varying (interval) motion reliability and optimization design (integrated), has a very For the important theoretical significance and practical value, this paper takes the integral steering mechanism and the rack and pinion steering mechanism as the research object. After analyzing the reliability and optimization synthesis of the steering mechanism's time-varying motion, the time variant motion reliability method is discussed in detail.
The main research work in this paper can be summarized as follows:
1, based on the motion analysis of the integral steering mechanism and rack and pinion steering mechanism widely used in automobiles, the error probability model of steering mechanism is established considering the uncertainty of components size and randomness of mechanism.
2 introduction of structural reliability analysis method on the crossing rate and the crossing rate concept, combined with a two order moment method (FOSM) and for the first time through the Poisson approximation method to derive time-varying (interval) mechanism motion reliability analytical expressions. Based on the established integral steering mechanism and a gear rack type steering mechanism the time-varying dynamic reliability model. And through examples and the reliability were analyzed, results show that the mechanism of time-varying reliability is always less than point reliability, meet point reliability does not mean that meet the time-varying reliability. Obviously, time-varying mechanism motion reliability is more reasonable than the traditional reliability, it in the whole range of motion as the object of study, can reflect the possibility of institutions to meet the intended function of the sport in the whole process.
3 for the optimal design of mechanism (integrated), this paper puts forward the mechanism of time-varying reliability optimization method. The comprehensive integral steering mechanism of time-varying reliability optimization model is established through numerical examples, it with that of the deterministic optimization method and reliability optimization method were compared and analyzed. The results show that the mechanism of time-varying reliability the optimization method is better than the deterministic optimization method and reliability optimization method is more superior, can not only meet the reliability requirements and structure error reduction mechanism, and its optimal solution is more than the other two kinds of 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

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