Papers by Author: Guo Zhi Zhang

Abstract: Schedule control is the major issue in project management, and to predict the construction schedule effectively is important practically. The article mainly predicts the schedule of a project based on BP neural network. The result shows that the predicted value is more accurate than the value calculated by linear method.

Abstract: The vibration phenomenon appeared in orthogonal experiments of turn-milling machining of micro-miniature shafts. In order to study the causes and conditions of vibration, the vibration test experiment system was established and frequency spectrum analysis of acquisition data was done. The results show that its machining vibration is caused by the low-frequency flutter of the milling spindle. And the coupling relationship of the micro-miniature shaft and the turning spindle was discussed with FEM. The results show that the vibration of the micro-miniature shaft does not affect the vibration of the turning spindle, while the vibration of the turning spindle can cause the vibration of the micro-miniature in their low order vibration mode.

Abstract: The simulation method for ARB(accumulative roll bonding) and the constitutive model of the ARB specimen were studied. Based on the ZA(Zerilli-Armstrong) model, with MSG(mechanism-based strain gradient) theory and Hall-petch principle, considering its temperature, strain ratio and the effect of the texture variation to the mechanical property, its dynamic constitutive model was established, and verified through the experiment. Moreover, the finite element simulation method for ARB process based on the dynamic constitutive model established was proposed and verified through the experiment. The study in the paper provides analysis method and theory foundation for ARB

Abstract: Study on the effect of the surface manufacturing quality (roughness) to the friction between the surfaces. Based on the plastic theory of mechanism-based strain gradient (MSG) of the micro-plastic-mechanics and the contact theory, the theoretical model of the coefficient of friction between the rough surfaces and the non-linear finite element model between the grinding samples were established. Moreover, the surface stress distribution and the coefficient of friction were obtained through the sub-structure finite element method. The established model of static friction theoretical model and the accuracy of the finite element model were verified through comparing with the result of the static friction experiments between the grinding samples with different surface manufacturing quality. The study in the paper is important to the study on the surface friction mechanism.