Calculation Method Of Time-varying Mesh Stiffness With Faults And Dynamic Modeling And Simulation Of Gear System

Gear system is an important component of mechanical equipment.As for its huge bearing capacity, high efficiency of transmission,good accuracy of transmission and high compactedness of installation, the gear system is widely used in the dynamic transfer of mechanical equipment. On the influence of fatigue loading and other random factors, the gear is easily damaged.In order to avoid the happening of gear fault,it’s essential to study the failure mechanism and failure dynamic response of gear system.However, the gear system is a strongly nonlinear system which has various nonlinear parameters, such as time-varying stiffness, side clearance,transmission error and so on.These nonlinear features make it very difficult to study the failure mechanism and failure dynamic response of the gear system.So to study the modeling method, failure mechanism and dynamic response of the gear system has important theoretical value and reality significance.Based on the calculation method of time-varying stiffness of straight spur gear,this dissertation analyzes the influence on time-varying stiffness with tooth root crack and gear eccentricity. And the relevant calculation model of time-varying stiffness has been derived. An eight degrees-of-freedom gear system dynamic model is established.Based on the dynamic simulation of this model, the dynamic response of the gear system with different fault and various working condition is got. The main work is as follows:(1)A single tooth is simplified as a cantilever beam.Based on the energy method,the bending stiffness, axial compressive stiffness, shear stiffness, Hertzian stiffness and foundation stiffness have been derived and calculated. Finally the calculation method of total gear time-varying stiffness is got.(2)Based on the calculation method of normal gear time-varying stiffness, the calculation method of faulted gear time-varying stiffness with the faults of tooth root crack and gear eccentricity has been derived. And the gear time-varying stiffness with different degrees of faults has been calculated and analyzed.(3)An eight degrees-of-freedom gear system dynamic model is established. The time-varying stiffness which has been calculated is plugged into the gear model to calculated the dynamic response of the gear system with different faults.And the result is analyzed by time-frequency analysis method to acquire the influence on the vibration response with different degrees and kinds of faults.