【作者】 胡照林；

【导师】 轩建平；

【作者基本信息】 华中科技大学 ， 机械电子工程， 2007， 硕士

【摘要】 裂纹、碰摩转子在考虑弯扭耦合情况下,将表现出非常复杂的非线性动力学特性。本文以转子动力学以及非线性动力学理论为基础,对裂纹、碰摩转子弯扭作用下的动力学响应特性,特别是非线性特性进行理论研究,并通过实验数据分析验证理论结果的正确性。对含横向裂纹的单盘柔性Jeffcott转子建立力学模型,考虑裂纹开闭状况下的裂纹轴刚度变化情况,建立弯扭耦合振动方程,运用数值积分方法对弯扭耦合振动方程进行求解。在时域、频域上分析了裂纹夹角、深度、工作转速等因素对裂纹弯振的影响特性,以及裂纹的开闭特性。通过以速度为参数分岔图以及Poincare截面图讨论其弯曲振动和扭转振动非线性特性。分析表明:裂纹转子弯扭响应中出现分数次共振现象,同时扭转运动对弯曲振动非线性具有一定的抑制作用。同时建立碰摩转子力学模型,运用同样的分析方法对其弯扭振动进行数值仿真。由于碰摩转子的运动比较复杂,经常出现拟周期,混沌等复杂运动状况,因此本文通过以速度为参数分岔图以及Poincare截面图,重点讨论其弯曲振动和扭转振动非线性特性,复杂运动区域范围,以及各区域的运动特点。分析表明:碰摩转子的弯扭耦合作用使转子在局部碰摩转速区的弯曲振动频率成分更加复杂,其非线性现象更加明显,出现复杂运动的转速范围更宽。总体上说,碰摩转子考虑弯扭耦合作用后,其稳定性降低,但两者具有相同特性,那就是随着转速的逐渐增大,周期运动与复杂运动相间出现,并且弯振和扭振非线性振动具有很强的相似性。因此在实际应用中,应尽量避免这些复杂区域,以免造成系统的不稳定运转。最后,本文通过轴心轨迹、瀑布图对裂纹、碰摩转子的实验数据进行分析,得到的实验分析结果很好地验证了理论分析结论。本文碰摩、裂纹转子的理论分析结论对实际生产具有实践指导作用,并且其弯扭总体考虑来分析故障特征也是比较全面和准确的。更多还原

【Abstract】 In the condition of the bending-torsional coupled vibration, the cracked rotor and rub-impact rotor contain complex non-linear dynamic characteristic. Based on the rotor dynamics and nonlinear dynamics theory, dynamic characteristics of the cracked rotor and rub-impact rotor, especially the nonlinear dynamics characteristic, are investigated in this paper.The dynamic model of Jeffcott rotor with a transverse crack is built, then considering the unsymmetric stiffness, the differential equation of motion is established. Through computer simulation, the influences of the speed, the angle, and the depth of the crack on the vibration are studied. And the breathing characteristic of the crack is also analyzed. Using numerical integral method, bifurcation diagrams, Poincare mapping and spectrum diagrams are used to analyze the nonlinear dynamic characteristics of the system. It is found that 1/3X and 1/2X sub-syntonic resonances occur with the cracked rotor accelerated both in flexural and torsional vibration, and the non-linear movement of flexural vibration is restrained by the torsional vibration.By the same method, the characteristic of rub-impact rotor is studied. The movement of rub-impact rotor is very complex, and appears quasi-periodic and chaotic phenomenon, so the nonlinear feature and the region of instability are primarily studied in this paper. Through the bifurcation diagrams, Poincare mapping, the vibration characteristics and nonlinear characteristics are analyzed. It is shown that the movement of rubbing rotor with torsion is more complex, and the nonlinear feature is also much more notable, the speed period of complex movement is wider too. In general, the movement with torsion is much move unstable. But as the speed increased, the periodic movement and complicated movement appear at intervals both in flexural vibration and torsional vibration.Finally, through the running orbit and the waterfall diagram, the experimental data are analyzed. And the answer validated the theoretical results. So they can be used as guidance to practice. And the analysis of flexural and torsional vibration together is much more suitable for the fault diagnosis.更多还原