| Spiral bevel gear transmission system connects the drive shaft and the driven shaft through the spiral bevel gear pair,which can realize the transmission of speed and torque between shafts and change the direction of power transmission.Widely used in shipbuilding,aviation,aerospace,automotive and other engineering fields.The gear teeth of spiral bevel gear pair are easy to break when they work in alternating conditions for a long time.The broken teeth will directly lead to the abnormal change of the meshing excitation of spiral bevel gear pair,and then lead to the abnormal torsional vibration of the transmission system,and even harm the service life of the equipment.Therefore,it is of great significance to study the torsional vibration response characteristics of the transmission system under the condition of broken teeth fault for the operating state monitoring and fault diagnosis of the gearbox.The research work of the project can provide reference for the working condition monitoring of the gearbox and the fault diagnosis of spiral bevel gears.The main research contents and conclusions are as follows:1.Taking the tail transmission system of a certain helicopter as the research object,based on the quantitative modeling method,the finite element model of spiral bevel gear transmission system was established;The natural frequencies and modal shapes of torsional vibration are studied.All the order of the transmission system are derived from each component axis except the first and second order natural frequencies of the system coupling.The correctness of the proposed transmission system model is verified by comparing with the natural frequencies of existing models in the literature.The rotational inertia of each gear in the transmission system is positively correlated with the numerical value of natural frequency variation.The change of gear pair meshing stiffness has different effects on the natural frequency of each order,and the effect on the first and second order is greater.2.The model of spiral bevel gear pair with broken teeth fault was established based on3 D modeling software,which was imported into ANSYS for cutting teeth and meshing,and finally the finite element contact analysis was carried out.With the increase of the fault degree of broken teeth,the deformation and meshing force of spiral bevel gear teeth change in different degrees.Based on the meshing principle,the meshing excitation of various broken teeth fault models is calculated.By comparing the experimental data spectrum with the simulation data spectrum,the validity of the spiral bevel gear pair model with broken teeth fault is verified.3.The helical bevel gear pair model with broken teeth fault was implanted into the established quantitative finite element model,and the torsional vibration response was analyzed from three aspects of time domain,time domain index and frequency domain;The vibration amplitude of the horizontal shaft node is the largest,followed by that of the tail-inclined shaft.The vibration amplitude of the driven gear node of the tail reducer is the largest,the driven gear of the middle reducer is the second,and the driving gear of the tail reducer is the smallest.The amplitude of the gear node is positively correlated with the moment of inertia of the gear.The peak factor and margin factor in time domain indexes are more sensitive to the change of broken tooth fault degree.In the frequency domain diagram of the shaft nodes,the rotating frequencies fe1 and 0.5 fe1 of the horizontal axis are the main ones,while the meshing frequency and its double frequency of the two-stage reducer are the main ones in the gear nodes.With the aggravation of the fault degree of broken teeth,the more abundant the low frequency bands below the first-order meshing frequency in the spectrum diagram of gear nodes,the higher the energy contained in them. |
