ISSN   1004-0595

CN  62-1224/O4

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摩擦学系统的系统理论研究和建模

On the System Theory and Modeling of Tribo-Systems

  • 摘要: 摩擦学的系统思想是在摩擦学诞生初期就已经被提出来。由于摩擦学的理论体系研究一直进展缓慢,摩擦学系统的系统理论和建模研究也一直进展缓慢。本文在摩擦学3个公理基础上,从一般系统理论与工程系统分析方法相结合出发,研究了摩擦学系统的功能和构成,论述了摩擦学系统在运动系统中承担的运动保证功能,即保证运动系统各部分之间有确定的相对运动。运动保证功能由全体摩擦副共同实现,并有若干辅助子系统支持摩擦副的可靠工作,它们一起构成了摩擦学系统。摩擦学系统是为研究摩擦学行为而从运动系统中抽象出来的运动系统的子系统。从系统功能出发,摩擦学系统的状态参数集里必然含有与构件运动有关的参数,这些参数对于摩擦学研究非常重要。摩擦学系统结构既与历史关联又跟随状态变化,因此是非定常非线性系统。这2种变化对于摩擦学系统具有不同的时间尺度,也就是说具有非常长的周期和相对非常短的周期,这就为能够以不同时间尺度的分段定常和分段线性化求解计算提供了理论根据,从而在模型中考虑了此前为不能积分而对结构引入的大量简化,这些过去被忽略的因素对摩擦学系统其实是很重要的。同时,也使得能够在建模中将不同学科行为通过与历史关联和跟随状态变化的系统结构进行耦合和共同作用于系统。文章给出了一个缸套-活塞裙部,连杆大小头和曲轴轴承摩擦学系统的算例。

     

    Abstract: System thinking has arisen since the early stage of tribology study. No significant development in the overall theory of tribology results no significant development in the system theory and modeling of tribo-systems. Based on the three axioms of tribology and by integrating the general system theory with engineering system analysis, the function and the composition of tribo-systems are investigated. It is concluded that tribo-systems provide for moving systems a motion guarantee function which keeps all components in a moving system with definite relative motions. The function is implemented by all tribo-pairs in the system together with several sub-systems to support tribo-pairs working reliably. Therefore tribo-systems are the sub-systems of moving systems abstracted from which for investigating tribology behaviors therein. The motion guarantee function determines that there must be parameters concerning with motions of components in the system state parameter sets and these parameters are very important for tribology study. The structure of tribo-systems is on history depending and with state variation following. Therefore tribo-systems are time-variable and non-linear. Fortunately such two kinds of variations are with different time scales, of very long period and of very short period in comparison with the former. It founds a theoretical base to establish an algorithm of piecewise stationarized and piecewise linearized with different time scales. Most simplifications taken previously in structure modeling to avoid unintegrable can then be considered. Many factors simplified before are important and cannot be ignored for tribo-systems. Simultaneously the behaviors of different disciplines can then be coupled and applied together on the tribo-system through a history depending and state following structure as well in modeling. A tribo-system including cylinder liner – piston skirt pair, conrod big and small head bearings and crank shaft bearings of IC engines is given as a computational example.

     

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