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To accurately evaluate the remaining life (RUL) of rolling bearings under small sample conditions and strong noise interference, a RUL prediction scheme using adaptive variational mode decomposition (VMD) and double-discriminator conditional CycleGAN (DD-cCycleGAN) is put forward. Combining chimp optimization algorithm (ChOA) with VMD, an adaptive VMD algorithm based on ChOA is presented, which selects effective mode components for reconstruction and reduces interference from strong background noise. A DD-cCycleGAN is developed to generate new samples which not only retain sample information of source domain, but also resemble samples of target one. A LSTM network after training is utilized to predict the bearing RUL in test samples. The performance of this scheme was validated by using the XJTU-SY bearing test dataset. The comparison analyses demonstrate this scheme has strong noise resistance and high accuracy. [ABSTRACT FROM AUTHOR]

(1) Background: To better understand the dynamic characteristics of a ball bearing with an elastic ring squeeze film damper (ERSFD) under sudden unbalance, a novel dynamic model was established by fully considering the coupling between the ERSFD, bearing outer ring (the journal), rotor, and disc (loading bearing); (2) Methods: An improved secant method was developed to determine the initial eccentricity values of the bearing's outer ring and the disc. The dynamic response of the outer ring under different speed ratios, damping ratios, and mass ratios was solved using the variable-step Runge–Kutta method; (3) Results: In comparison, a low-speed ratio, high damping ratio, and low mass ratio were more conducive to suppressing the bearing vibration. When the imbalance was suddenly introduced, the displacement amplitude of the eccentricity, transmissibility, amplitude–frequency response, and the radius of the outer ring center locus increased; (4) Conclusions: This work provides a reference for further studying the nonlinear vibration of rolling bearings coupled with an ERSFD. [ABSTRACT FROM AUTHOR]

The dynamics model of cylindrical roller bearing (CRB) in aeroengine main shaft was promoted and solved by Hilber–Hughes–Taylor (HHT) integer algorithm with variable step in combination with symmetric multiprocessing (SMP) parallel solving technology, and a finite element model of roller to cage contact was built. The dynamic characteristics of CRB at the stage of start-up and stop were analyzed firstly, and then, the collision forces between rollers and cage were used as the boundary conditions of the finite element model to discuss the influences of working conditions, structural parameters, and materials on the stress distribution and safety characteristic of cage at the stage of start-up and stop. The findings will provide the theoretical basis for the designing of CRB in aeroengine main shaft.

Based on dynamics analysis of rolling bearing,the dynamics differential equations for cylindrical roller bearing with trilobe raceway and elastic support are established. By using the predict-correct integer algorithm with variable step,the dynamics equation is solved,and the influence of structural parameters of elastic support and working conditions on the vibration characteristics of the bearing is investigated. The results show,that the inter-groove number,thickness circular beam and transition angle of elastic support have significantly effect on the vibration of bearings,but gap of groove has little effect on it. In a certain range of load and rotation speed,elastic ring can effectively decrease the vibration of bearing,elastic support with lesser inter-grooves can enlarge its impact-absorb range of load and speed,the elastic support also can reduce the bearing vibration caused by the impact load.

Based on the dynamics theory of rolling bearing,the dynamics model and nonlinear dynamics differential equations of the cylindrical roller bearing during the start up are obtained by considering of the change of lubrication state between rollers and rings. The simulation analysis for the effect of radial loads,accelerations of the inner ring,viscosity of lubricating oil and working temperatures on the slippage characteristics of roller are carried out by solving the equations. The results show,during the start up of the cylindrical roller bearing,the rotational speed growth of the roller about its axis is not linear but stepwise,and there exists a more serious slippage in the early start. The slippage ratio of roller varies heavily with radial loads or accelerations of inner ring. A proper increase in viscosity of lubricating oil or an appropriate decrease in working temperature can reduce the slippage of roller to prevent the raceway scratch effectually during the start up,and effect extent of working temperature is smaller than viscosity of lubricating oil.

Under high temperature and water lubrication environment, the properties of high temperature non magnetic alloy GH05 material for bearings will change,which will affect the wear coefficient of material so as to affect the bearing wear performance,resulting in increased vibration and noise of bearings. The friction and wear tests of high temperature non-magnetic alloy GH05 under high temperature and water lubrication were carried out by using a high temperature friction and wear tester,and the effects of temperature,load and lubrication on the friction and wear properties of the material were analyzed.The wear coefficient of the material was obtained,which provided test data for bearing life evaluation under special working conditions and lubrication conditions.The results show that the friction coefficient of the bearing material GH05 is about 0. 53 at 300 T and about 0. 35 with water lubricating medium.Compared with the friction coefficient at 25 T,the friction coefficient at 300 T has a smaller fluctuation range and a stronger stability. Compared with the friction coefficient under dry friction state,the friction coefficient under water lubrication condition is smaller,and the stability of friction coefficient is better. With the increase of temperature,the wear resistance of the GH05 material decreases. At the same test load, the wear volume of GH05 material under dry friction at high temperature of 300 T is the largest,and the smallest under water lubrication at room temperature.The wear coefficient of GH05 is from 1. 93x10 7 mm2/N to 3. 02x10 7mm2/N under dry friction at high temperature of 300 T . [ABSTRACT FROM AUTHOR]