Papers by Author: Li Gang Cai

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Authors: Jun Jing Yang, Hong Yan Chu, Li Gang Cai, Lei Su
Abstract: Abstract : Aiming at the controlled object with large lag, model uncertainty and time variation due to the effects of working environment in printing process, and printing process requires few adjustment times, this paper designs a T-S fuzzy controller based on the theoretical model of printing color quality control, and uses the genetic algorithm to optimize the initial control rules of fuzzy controller . The optimization method aims at the problems of less known condition and the uncertain effects due to the environmental changes after the first printing. In the process of optimization, the theoretical model of the printing color quality control is used as the controlled object, and the parameters of control rule corresponding to the points of special error are optimized one by one, then the general fuzzy control rules can be got. Finally, an example illustrates the process of this method, and the robustness of the optimized fuzzy controller is analyzed. From the control results got by the optimized fuzzy controller, it can be seen that this method improves the control effects greatly, and reduces adjustment times. Finally, this paper gives some suggestions on its further perfection.
Authors: Jian Hua Wang, Fei Liu, Tie Jun Wang, Li Gang Cai, Yong Sheng Zhao, Wei Dong
Abstract: When the metal - carbon eutectic gets phase transition, the graphite crucible will be effect by the thermal stress and the phase transformation stress, which often make the crucible rupture, fail to achieve durability requirements, and then affect the research of high temperature eutectic fixed-point’s long-term stability and reproducibility. In order to improve the durability of crucible, the finite element software ANSYS and direct coupling method were used in this paper to analyze the heat-stress of Pt-C fixed-point crucible with sleeve (graphite sleeve) during the solidification. Based on the results of the simulation, we analyze the reasons of the breakdown of the crucible and propose two measures to improve the durability of crucible, which are adding graphite cloth or graphite foil between the crucible and the sleeve. Then we use ANSYS to analyze the two improved crucibles, and prove the effectiveness of these two measures.
Authors: Tie Neng Guo, Xue Li Yu, Fu Ping Li, Li Gang Cai, Ya Hui Cui
Abstract: Mechanical properties of the joints have impacted on the whole mechanical characteristics. Coupling the joint characteristics in the modeling of the machine tool is an important problem in machine mechanics analysis. In order to solve the joint modellings in the assembled structure, this paper presents a new method to creat beam elements between two symmetrical nodes on the contact surface of the joint. The stiffness and damping matrices of the elements are valuated according to the characteristics of the joint. To validate the accuracy of the proposed method, the modeling of an assembled structure with and without the joints is obtained and some corresponding experimental investigations are implemented. The error between the simulated and experimental results of the finite element model is less than 8.8%, while the error of the contact model often used in the existing literatures is one times bigger than the proposed model.
Authors: Zi Jing Yang, Li Gang Cai, Gui You Chi, Gen Mao Yu, Li Xin Gao
Abstract: A redundant lifting wavelet packet analysis based on variable parameter was presented, which was used to extract the weak fault features of bearing submerged in background noise. Through different choices of parameters in the design formula of predictor based on least square method of fitting, six asymmetric wavelets with various characteristics were constructed, which were then respectively used for redundant lifting wavelet packet decomposition to signal layer by layer. All the results obtained by decomposition were adopted to establish the objective function of minimum norm, through which the optimal wavelet that best matches the feature information is selected for each node signal. The node signals got by last decomposition were utilized for wavelet packet energy analysis, while the node signal with maximum energy was chosen for single branch reconstruction and envelop spectrum analysis. The proposed method above is applied to process the engineering data of bearing with fault and good results are gained by which the effectiveness of this method is well validated.
Authors: Tie Neng Guo, Fang Jian Xi, Zhi Feng Liu, Qiang Cheng, Li Gang Cai
Abstract: Aiming at solving issues of load bearing deformation compensation and sympathetic vibration, this paper takes a large span and heavy load crossbeam of a domestic heavy-type numerical control milling planer for research object, the final purpose is to improve machining precision and stability of the heavy machine tool product. The load curve considering the influence of columns deformation, natural frequency and vibration model are obtained, respectively by the dynamic and static simulation analysis of the crossbeam with the finite element analysis method. Then, the modal analysis results are verified through the model experiment. Lastly, this paper presents an approach by estimating the load curve to improve machining precision, points out the weak links, and provides guidance for crossbeam structure design, optimization and reverse manufacture.
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