Research On Dynamic Characteristics And Damping Mechanism Of Rolling Bearing-Rotor System

The rotor system supported by rolling bearings is widely used in industry and its status in the industry is irreplaceable.At the same time,the birth of squeeze film dampers in the aviation industry and large rotating machinery also contributes an indelible contribution to the damping effect of the rotor system,especially for aeroengine systems with tight and complex structure and extremely demanding geometrical dimensions.Therefore,it has important scientific and technological value to analyze the vibration characteristics of rolling bearing and squeeze film damper,which lays the foundation for the future theoretical research.The numerical simulation and the numerical analysis of this model was carried on by using MATLAB numerical simulation software.The research deficiencies in this field at present were complemented and the research methods and forms were improved and enriched.The main content of this paper is accomplished in two aspects:(1)The dynamic model of the rolling bearing-rotor system was established by the method of lumped mass method,with the Hertz contact theory incorporated into the rolling bearing.And the differential equations were solved by Newmark-β method.The influence of the change of parameters such as the rotational speed,the number of rolling elements and the radial clearance of the bearing on the dynamic characteristics of the rotor system was analyzed emphatically.The vibration characteristics of the rolling bearing largely determine the dynamic performance of the rotor-bearing system.The keys to study the dynamic performance of the rotor system supported by rolling bearings are to understand the geometric structure of the rolling bearing,and to find out the working mechanism and mode of motion.Thus the dynamic characteristics of the model can be analyzed accurately.In this paper,the interaction model of the bearing inner ring,the rolling element and the bearing outer ring was established in order to be as realistic as possible to effectively simulate the practical motion of the rolling bearing.It replaces the bearing component model of bearing-rotor system simulated with the equivalent damping and stiffness in the past and solves the problem including the large difference between the the latter and the actual model,the lower calculation accuracy and a certain deviation between the theory and the reality.Therefore,according to the model of this paper,the above problems are well solved,and the comparison is made by experimental methods.The correctness of the theoretical model is well verified,laying an important theoretical foundation for future scientific research.(2)Reliable analysis on the dynamic characteristics of squeeze film damper,which is an important part of aviation and large rotating machinery,has some practical significance.Therefore,based on the above dynamic model of the rolling bearing-rotor system,the dynamics model of squeeze film damper is added.With regard to the study of squeeze film damper,the nonlinear dynamic response of the rotor system was analyzed based on the theoretical basis of the Reynolds equation,dynamic pressure lubrication theory,short bearing hypothesis and circumferential boundary conditions of the oil film force.The displacement response of the rotor system with and without squeeze film damper was compared from the shaft center orbits and the time history chart these two angles.And it is verified theoretically that the squeeze film damper does reduce the vibration under certain conditions and effectively reduces the amplitude of the rotor of rotating machinery.Besides,the stability of the rotor during the working process is also greatly improved.At the same time,the influence of stiffness characteristics of the“squirrel cage,in the squeeze film damper on the motion of the rotor system is studied.Since the different structure of the“squirrel cage”,the stiffness of the rotor system is changed.The research shows that the different stiffness of the“squirrel cage”directly affects the periodicity of the movement of rotor system and also affects the vibration amplitude of the system.Therefore,the research on the oil film damper also has certain theoretical value.