Papers by Author: Dong Li

Abstract: Based on DEFORM finite element software, the model of turning process of GMA was built, and the relation function among turning speed, turning depth and turning force of GMA turning system was achieved. Then, considering the turning force model, the dynamic equation of the turning system was established and the time domain and frequency domain of GMA turning system were discussed with different corresponding parameters. Results show that turning speed and turning depth have apparent effects on turning force of GMA turning system. Therefore, it is necessary to take the impact into consideration when analyzing dynamic characteristics of the turning system.

Abstract: Considering temperature variation and ΔE effect, the dynamic model of giant magnetostrictive actuator is established, meanwhile dynamic response of giant magnetostrictive actuator and relation between magnetic field and magnetization are discussed. The simulation indicates that the relation between magnetic field and magnetization is nolinear, and a loop appears. With the amplitude of magnetization increasing, nonlinearity and loop are more obvious, and the amplitude of response will increase. Under specific amplitude of magnetization, higher temperature will get larger amplitude of magnetic field. Compare above model with the model that ignored effect, it shows that the difference between their results decrease with the amplitude of magnetization increasing.

Abstract: Considering gyroscopic effect and flexibility of the shaft, the eight freedoms dynamic model is established. The dynamic characteristic and control quantity in different bearing rigidity and rotation axis are studied and discussed by optimal control theory. Furthermore, the controlling and the responding are discussed. The simulation results show that the bearing rigidity has great effect on the control quantity so that the elasticity of bearing must be considered. The asymmetry rigidity of rotational axis has little influence on stability. The conclusion may bring up theoretical references for precision control for rotor magnetic bearing system.

Abstract: A new twenty-freedom non-linear dynamic model for two-span dissymmetric elastic rotor system was established by considering the crack fault, rub-impact fault and oil film force. The complex motion characteristics of this system were numerically studied and the effect of different parameters on the system is investigated. Moreover, the both cases with and without crack fault were discussed in detail. The results indicate that the system has obvious single-period, period-doubling bifurcation and chaos phenomena. There are marked influences of the crack faults on the nonlinear characteristics of the system, especially under some the rotating speed. The case considering crack faults has different chaos region from the case without crack fault. The chaos phenomenon appears at lower rotating speed, and when the chaos comes again, the corresponding rotating speed extends backwards. Synchronously, the influence of crack fault increases along with the depth of crack. The results may provide theoretical references for rotor fault diagnosis.