Search

A permanent magnet synchronous motor (PMSM) driven system is a typical electromechanically coupled system. In this paper, to improve the operational performance and stability of the PMSM system, torsional vibrations due to the electromechanical coupling effects are studied. An electromagnetic excitation model was first established to consider the effect of torsional angle on magnetomotive force. Then, nonlinear torsional vibration equations of the driven system were obtained. In addition, an electromechanically-coupled torsional vibration mechanism based on natural frequency modulation of the system was revealed. Finally, the torsional vibration equations and coupled mechanism were validated against experimental results describing the actual torsional vibration and a numerical method was used to verify our theoretical analysis. The results provide a theoretical basis for the parameter design of electromechanical transmission systems.

We present a method for analyzing the transmission error of helical gear system with errors. First a finite element method is used for modeling gear transmission system with machining errors, assembly errors, modifications and the static transmission error is obtained. Then the bending-torsional-axial coupling dynamic model of the transmission system based on the lumped mass method is established and the dynamic transmission error of gear transmission system is calculated, which provides error excitation data for the analysis and control of vibration and noise of gear system.

A rigid-flexible coupling multi-body dynamic model which contains the structure system and transmission system is developed and the bearing dynamic reaction force is calculated. Then a vibro-acoustic coupling model of the gear system is established by taking the frequency histories of bearing reaction force as the boundary condition and the surface sound pressure and airborne noise of gearbox are calculated. Next, the experimental study on the airborne noise is performed on the experimental prototype to verify the calculation method. Afterwards, the airborne noise optimization model is established by taking the sound pressure at multiple field points and frequency bands as objective functions and the structure parameters of gear system as design variables. Finally, the response surface method (RSM) and normal-boundary intersection method (NBIM) are used to analyze and reduce the airborne noise of gearbox.

This paper presents a novel calculation method for accurately determining the meshing impact of helical gears. First, a mathematical model of meshing impact is constructed, the position of the impact point and the length of the impact contact line are determined, and the analytical formula of the helical gear pair impact force is deduced. Second, an approach for gear transmission mesh generation at any meshing position is presented, and an automatic modelling program for tooth mesh analysis is developed. The rationality of the analytical mathematical model is validated based on the developed finite element program. In addition, the meshing impact time is determined, and the effects of the input torque, input speed and tooth width on the impact force are analysed. The main conclusion is that the mathematical modelling method proposed in this paper can be used to quickly compute the meshing impact of helical gears.

The vibration characteristics of gear system have a significant influence on mechanical capacity and durable life of vertical mill reducer. In order to improve the performance of reducer, this paper present the research on inherent characteristic and dynamic response of vertical mill reducer. First of all, the finite element model coupled gear-rotor-bearing-housing of reducer is established including internal dynamic excitation. Then, the natural frequencies and natural modes are worked out by mode analysis, which indicates resonance phenomenon will not occur in reducer system. Finally, the vibration displacement, velocity and acceleration of the reducer are obtained through dynamic response analysis, which illustrates the structure vibration energy mainly concentrates in the engage frequencies and their multiples.