Theoretical Study On Contact Resonance Characteristics Of Ball Bearing System Under Multi-frequency Excitation

Ball bearings are the common support and transmission components of rotating machinery.The main exciting force and dynamic characteristics of ball bearings should be fully considered in the dynamic design of bearing-rotor system.However,it is extremely difficult to analyze the dynamic mechanism of the system,because the ball bearing is a non-linear mechanical part containing a variety of nonlinear factors such as Hertz contact,bearing clearance and varying compliance(VC).The VC excitation is an inevitable alternating excitation characteristic of ball bearing system,and the induced VC resonance and internal resonance characteristics are typical nonlinear vibration behaviors,which affect the stability and security of the rotor system.Recently,these relevant problems have received continuous attention at home and abroad.For example,a certain China military aircraft has been repaired many times due to the hysteretic jump fault caused by the main rolling bearings.Additionally,unbalanced excitation is noticeable that could lead the rotating member additional loads,which is a common damage factor of rotating equipment and component.Such fault emerging,the vibrational amplitude of the system gradually increases over time.To solve above problems,this text will be deeply address on followings.(1)The influencing factors such as rotor speed,damping and bearing clearance is considered,then the dynamic stiffness of the system and its prediction from the dynamic equivalent natural frequency of the system is studied.(2)Using the classical two-degree-of-freedom ball bearing model,with the aid of numerical integrations,the harmonic balance-frequency domain/time domain conversion(HB-AFT)method with the homotopy continuation is used to perform Floquet stability analysis of the characteristics of VC primary resonance and internal resonance,and the evoluting mechanisms of the complex response behavior of the system are also analyzed.(3)Exploring the response characteristics of the complex behavior of the system under the combination of VC excitation force and unbalanced excitation.