Research On Failure Mechanism Of High Speed Rolling Bearing Based On Spline Interpolation Displacement Excitation

Rolling is widely used in rotating machinery and equipment,especially high-speed rotating machinery,due to its small friction torque,easy lubrication,maintenance,and good interchangeability.The manufacturing precision,running stability and safety performance of rolling bearings almost completely determine the quality of the host equipment.With the continuous development of host equipment,the requirements for bearing reliability and vibration performance are getting higher and higher.Therefore,conducting the fault simulation of the bearing to obtain its dynamic response of acceleration under partial faults,and analyze its dynamic characteristics is of great significance for bearing fault detection and intelligent fault diagnosis.In this paper,a twodegree-of-freedom and multi-degree-of-freedom nonlinear fault dynamic model of rolling bearings is constructed by introducing a new displacement excitation function which based on the spline interpolation function.Using Newton-Raphson algorithm and fourth-order Runge-Kutta algorithm to solve the model can obtain the acceleration dynamic response data under the different local faults and different speeds.The validity of the proposed model is verified by comparing and analysis between experimental data and simulation data.The main research contents are as follows:(1)Considering the complexity and variability of the bearing operation environment as well as the randomness and time-variability of the bearing fault height.Based on the principle of statistics,a series of height values satisfying the normal distribution are generated randomly by fixing the maximum depth of local faults of bearings,which represent the change of fault height in the fault area.Then the spline interpolation function was used to fit the peak point and the motion trajectory of the rolling elements in the fault area was obtained.Finally,combining with the geometric relation of the bearing,a new displacement excitation function is established based on the relationship between geometry and motion of bearings.By introducing the displacement excitation function into the bearing dynamics model,the influence of local faults on bearing vibration signals is characterized.The results show that when the rolling element passes through the fault zone,it will produce multiple time-varying shocks,and it has more obvious positive and negative symmetrical shocks,which can better simulate the dynamic response of the bearing.(2)Based on the traditional two-degree-of-freedom dynamic model,considering the effects of centrifugal force,gyro torque,and time-varying contact angle on the rolling elements of the bearing under high-speed operation,combined with the fault displacement excitation function proposed in this paper,a high-speed angular contact ball bearing with two degrees of freedom is constructed.And the dynamic response of acceleration under different fault sizes and different speeds are compared and analyzed by solving the model.(3)On the basis of the previous,considering the five degrees of freedom of the inner raceway of the bearing,the three degrees of freedom of the rolling elements and the three degrees of freedom of the cage,as well as the interaction between the various components,the multi-degree of freedom dynamic model of the angular contact ball bearing is established.And the vibration acceleration response of the bearing and the dynamic response of the cage were obtained and analyzed visually.(4)Through experimental design and built the test bench,the acceleration vibration signal of the bearing was collected.By comparison and analysis of the time domain and frequency domain characteristics under different fault sizes and different speeds between measured data and simulation data,it can be seen that the acceleration vibration signal obtained by the proposed model has a good match with the actual data,especially in terms of the fault trend.And the validity and rationality of the proposed two-degree-of-freedom and multi-degree-of-freedom fault dynamics model are verified.Therefore,in terms of dynamic modeling and simulation of bearing with the localize surface defects,the new displacement excitation function based on spline function and failure dynamics model proposed in this paper can obtain acceleration and vibration data that are more similar to the test data,and can better assist in bearing failure detection and bearing failure mechanism research.