Fault Modeling And Dynamic Characteristics Analysis Of Cylindrical Roller Bearings Based On Explicit Dynamics

Rolling bearings are used in high-speed,heavy-load and other complex working conditions for many years,local defects are generated on the working contact surface of its components.Early fault diagnosis is used for fault identification in industrial production.At this stage,due to the low efficiency of early fault identification,abnormal vibration of bearings occurs,more defects are induced,and the safety and stability of the entire mechanical equipment are affected,even irreversible losses are caused.Therefore,rolling bearings need to be refined for fault diagnosis,and refined fault diagnosis requires research on the bearing expansion mechanism and internal dynamic characteristics.In order to explore the expansion mechanism and dynamic characteristics,a finite element model for local failures of various components of cylindrical roller bearings was established and verified;the dynamic characteristics of different component faults(outer ring,inner ring,rolling element and cage)were studied respectively;The functional expression between the fault size and operating conditions of the bearing rolling element and the bearing contact deformation was obtained,and the influence of different fault positions of the cage on the bearing contact characteristics was studied;based on the segmented displacement excitation function,the outer ring fault bearing was established dynamic model,and the advantages of the segmented displacement excitation model were compared with traditional models.The main research contents are as follows:(1)The problem of the differences and similarities in the internal dynamic characteristics of bearings when different components fail had not been resolved.The elastic deformation and damping force of the raceway were considered,and single failures of the inner ring,outer ring,rolling body,and cage were introduced respectively.The finite element model of the cylindrical roller bearing was established,and the effectiveness of the model was verified through theoretical and experimental verification.At the same time,when different components of the bearing fail,the similarity and differences between the dynamic characteristics of each failed bearing were studied.The results show that the stress at the front end of the fault will lag,and the stress at the rear end will advance,with the largest change in stress during the outer ring fault.(2)Aiming at the phenomenon that the contact length and contact characteristics of rolling bodies and raceways are affected by faults.The relationship between the contact characteristics of rolling element fault bearings and the fault size,rotational speed,and load was investigated.The functional expressions of various parameters and contact deformation were proposed.At the same time,when the cage was in different fault positions,the collision force and collision position between the rolling element and the cage were studied.The results show that the influence of fault width on the abrupt contact force is greater than that of load and rotational speed,and the abrupt contact force changes more closely to the bearing in the load bearing area.(3)Aiming at the problem that the current bearing failure pattern cannot be accurately reflected through a single displacement excitation function.The displacement excitation of the rolling element is obtained through finite element models with different outer ring fault widths.The displacement excitation is segmented and fitted according to the fault location.A new segmented displacement excitation function dynamic model is proposed.The segmented excitation model is compared with traditional models,and the advantages of the segmented displacement excitation model are obtained.At the same time,the impact of the fault width on the bearing vibration characteristics is studied based on the segmented excitation model.