Research On Nonlinear Dynamics Of Planetary Gear Transmission System In Fault State

Wind turbine gearbox is the heart component of the wind turbine,and planetary gear system is an important part of the wind turbine gearbox which has a high fault rate and is difficult to identify.At present,the vibration mechanism and failure mechanism of the wind turbine gearbox remain unclear.The nonlinear dynamics vibration characteristics,coupling characteristics and failure characteristics are studied on the multi-stage gear transmission system of planetary gear rig which simulate the wind turbine gear transmission system.This study serves as a theoretical basis for the online detection and fault diagnosis of the multi-stage gear transmission system and wind turbine gearbox.This study uses the combining method of numerical simulation and experimental analysis,and analyzes the nonlinear dynamics vibration characteristics,coupling characteristics and fault vibration characteristics of the multi-stage gear transmission system of planetary gear which contains two-stage fixed-axis gear and one-stage planetary gear.The main research contentsThe torsional dynamic models of one-stage fixed-axis gear,two-stage fixed-axis gear,planetary gear transmission system and multi-stage gear transmission system of planetary gear are established respectively according to the centralized mass method.Normalize the models of four systems,and obtain the nonlinear dynamic equations of each system.By solving the nonlinear dynamic differential equations of four systems under the normal condition,the nonlinear dynamic characteristics of each system are obtained.Comparing the dynamic characteristics of the one-stage gear with the two-stage gear,and the two-stage gear with the multi-stage gear.Study the coupling characteristics and dynamic related characteristics of the two-stage gear and the multi-stage gear.It finds that the coupling characteristic of multi-stage system makes the jumping point decreased,and the dynamic related characteristic introduce chaos of the planetary gear into the fixed axis.The crack and chipping fault are simulated through the time-varying meshing stiffness model,and the wear fault is simulated by the comprehensive meshing error.The fault characteristics of three single fault of fixed-axis gear crack,planetary gear chipping and wear in each system,and two kinds of coupling faults of fixed-axis gear crack and planetary gear chipping,fixed-axis gear crack and planetary gear wear of multi-stage gear transmission system of planetary gear are analyzed.Comparing the dynamic characteristics of the same fault in different system and summarizing the fault characteristics and fault coupling characteristics of all kinds of faults,find out the characteristics of fault frequency and related failure frequency in the multi-stage gear transmission system of planetary gear.The unknown peaks in the experimental signal are identified by the related frequency characteristics,and the faults of the experimental rig are identified according to the feature of the related frequency.The change process of system stability with backlash can be obtained through the stability analysis of multi-stage gear transmission system of planetary gear.Be aimed at the sub-harmonic resonance of system,study the occurrence interval of the sub-harmonic resonance and the parameters which influencing the sub-harmonic resonance.Analyzing the effects of the single fault and coupling fault on the system sub-harmonic resonance and stability.The study shows that the fixed-axis gear crack and wear fault have large effects on the stability of the system.The effect of planetary gear chipping fault on the stability of the system is almost invisible.The coupling of three potentially makes the system through the limit cycle crack into chaos.