Gearbox Vibration Signal Analysis Based On Rigid-flexible Coupling Dynamics Model And Experimental Study

The vibration of transmission directly affects the vehicle riding comfort. Vehicle transmission can mainly be divided into two types: fixed-axis gearbox and planetary gearbox. Compared with fixed-axis gearbox, the structure of planetary gearbox is complex, and whose vibration spectrum is complex too. Since the vibration signal produced by the normal planetary gear system shows the same characteristics as the fault fixed-axis gear system. It is important to analyze gearbox vibration signal under normal and fault situation. The main results of this paper are as follows:(1) Construct a gearbox rigid flexible coupling multi-body dynamics model. Using CATIA three dimensional modeling software, a fixed-axle gearbox and a planetary gearbox which contains three planetary gear is established. Using LMS Virtual.lab software, and considering the actual gearbox on the components of the connection, gear stiffness and damping characteristic, a gearbox multi body dynamics model is established. After the gearbox flexible processing, the gearbox rigid flexible coupling multi-body dynamics model is obtained.(2) According the fixed-axis gearbox rigid flexible coupling dynamic model, the vibration responses of different fault types are calculated, and the characteristic frequencies are analyzed. It is found that: the vibration response of the normal gearbox only contains the meshing frequency and its harmonics. For the stationary-type faults, the vibration response includes the rotation frequency, the meshing frequency and its harmonics and their modulation sidebands with the interval of rotation frequency. For the impact-type fault, the vibration response includes the natural frequency and its rotation frequency modulation sidebands, the meshing frequency and its harmonics and their rotation frequency modulation sidebands.For compound-type fault, the vibration response of gear system includes all the vibration characteristics of the normal, stationary-type fault and impact-type fault at the same time. The correctness of the simulation analysis is verified by the test results.(3) The vibration of the planetary gearbox with normal and typical faults are simulated and analyzed. Under normal circumstances, only when the vibration frequencies are integer times of the planetary gear number, the corresponding amplitudes are not zero.When there is a broken fault on the ring gear, vibration response also includes the natural frequency and the meshing frequency and its harmonics, all of these frequencies are modulated by three times the frequency of planetary carrier and its harmo nics.When there is a broken fault on the sun gear, the natural frequency of the gear ring will be aroused too, and whose modulation sideband is characteried by the 3 times relative frequency of the sun gear and planetary carrier. In the vicinity of the meshing frequency, the weak modulation components of the rotation frequency of planetary carrier and its harmonics are also generated when the speed of slight fluctuations. The simulation results are verified by the experimental analysis.