【作者】 陈威；

【导师】 孙保苍；

【作者基本信息】 江苏大学 ， 应用数学， 2006， 硕士

【摘要】 旋转机械在机械、动力、交通、航空航天及空间技术领域中占有极其重要的地位，也是国民经济的关键装备之一。随着生产与科学技术的迅速发展，对于转子系统非线性动力学行为的研究，已经发展成为当前相关领域的一个热点。基于这一背景，本文以弹性转子一轴承系统为研究对象，就其故障消除问题展开研究，取得了一些有益的结果。旋转机械在运行过程中，事故时有发生。研究表明，非线性振动是导致系统故障的主要原因。只要通过微扰，将混沌等复杂行为转化为简单的同步周期运动，即可确保机器正常运转。基于这一思路，本文并没有像传统的反馈控制法那样，求出不稳定的目标周期轨道，而是直接将位移反馈到系统中去，再用数值模拟研究其非线性动力学行为，借助相图、分岔图、Poincare映射图分析系统的运动形态，检验控制的效果。结果显示，所用的方法实现了预先设想，由于该法只需较小的反馈增益(小于0.5)，且是双输入的，因此在实验中便于操作。本文首先介绍了一种精确的短轴承非稳态非线性油膜力的解析公式，然后介绍了用于分析转子—轴承系统在非线性因素作用下运动形态的方法。其次在上面提供的理论基础上，建立弹性转子—轴承系统动力学模型，采用龙格—库塔算法来求解系统的运动微分方程，画出了数值模拟图，结果显现系统中存在丰富的周期、概周期甚至混沌运动。第三，在上述模型中引入位移反馈，仍然利用龙格—库塔算法求解并作出了受控系统的数值模拟图。结果表明这种控制方法可以将混沌、概周期以及高周期运动转化为同步周期运动。最后，对本文中所取得的结果进行了总结，同时指出了本文的创新之处及存在的不足。更多还原

【Abstract】 Rotating machinery plays a very important role in machinery, power, communication, aerospace, space technology and so on. It is also one of main equipments in national economy. Along with the rapid development of production, science and technology, research on some problems of nonlinear dynamical behaviors of a rotor system has evolved to be a top point in related fields nowadays. Based on this background, the method removing abnormal behaviors consisting in the flexible rotor-short journal bearing system is studied in this paper, and some useful results are got.During the operation of rotating machinery, serious accidents often happen. In fact, the irregular behaviors of machinery are mainly caused by its nonlinear vibrations So, the normal operation of system can be obtained if its complicated motions such as chaos are converted into simple synchronous periodic motions by small perturbations. Based on this idea, the displace feedback terms are introduced into the system directly in this thesis, instead of solving the unsteady periodic target orbit in traditional feedback control method. Then, the nonlinear dynamical behaviors of the controlled flexible rotor-short journal bearing system are studied by using numerical simulations.The motion characteristics and the control effects are analyzed by phase diagram, bifurcation diagram and Poincare maps. Researches show the results agree with the imagination. Furthermore, the approach adopted is easy to be used in experiment, for it only needs a small feedback-gain (less than 0.5), and only two variables are required to be controlled.Firstly, the analytical formula of the unsteady oil film force of the short journal bearing, is cited in this thesis. In addition, the methods for the research of the motion characteristics of system are introduced.Secondly, based on the theories above, the dynamical model of the short journal bearing-flexible rotor system is established, and the motion differential equation of the system is solved by using the Runge-kutta method, then, the diagrams about uncontrolled system are plotted by numerical simulations. Results show the various forms of periodic, quasi-periodic and chaotic motions.Thirdly, two displace-feedback terms are added to the model mentioned, the motion characteristics of the short journal bearing-flexible rotor system are investigated under the consideration of control, and its motion differential equation is solved by the Runge-Kutta method, then, the diagrams about controlled system are plotted by numerical simulations. Results show this control method can transform chaotic, quasi-periodic and multiple periodic motions into synchronous periodic motions.Finally, the results we’ve obtained are summarized in the end of this thesis. Also some creativities as well as existing problems are pointed out.更多还原