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Tianyan Liu,Xiangyang Xu,Minghui Zhang,Runbo Zhang,Yue Wu,Hongzhi Ji,Yanfang Liu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7
Under the engaging process, excessive temperature of clutch plates may lead to thermal failure. Existing research has failed to find the hot spot and the radial temperature difference real-timely. They also neglected the influence of dynamic sliding process and hydraulic characteristics. Thus, a multi-domain dynamic model of the whole clutch was proposed, involving the mechanical dynamics, the hydraulic dynamics and thermics. With the thermal resistance network method, the real-time axial and radial temperature prediction of clutch plates was realized. The highest temperature occurs on the friction pairs of axial middle and the maximum value occurs on the radial 5th mass. Compared with the results by FEM, the deviation is about 6.5 %, but the time duration is reduced significantly. Furthermore, the influence of the outer hub vibration (160 Hz, 0.2 Hz) on the dynamic characteristics was discussed. This work was tested to be an effective and good basis for the health prediction of wet clutches.
Jiang Tianyan,Deng Biao,He Qiaoqing,Bi Maoqiang,Chen Xi,Bao Lianwei,Zhou Xin 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2
This paper presents Weibull failure models by experimental work and the step-up accelerated electrical–thermal test of oil-impregnated paper with 0.2 mm thickness is carried out under pulsating DC voltage at different temperatures. The breakdown voltage and failure time of the oil gap–paper insulation specimens at the same voltage duration is obtained by accelerated electrical–thermal aging test. The Weibull failure models of three-variable oil gap–paper insulation modified by Fallou and Ramu are established to analyze the failure data of oil gap–paper under different electric field intensities and temperatures. The statistical test method was used to evaluate the applicability and accuracy of two modified triple-variables Weibull failure models. The comprehensive test index of the Fallou-modified WFD is 1.6851, and the comprehensive test index of the Ramu-modified WFD is 1.8124. The Fallou-modified results were more accurate than Ramu-modified results in estimating the statistical distribution of failure data. Results show that the proposed triple-variable Weibull failure model could fully reflect the insulation state of oil gap–paper under the action of electric and thermal fields.
Jiang Tianyan,Zhang Tao,Li Yang,Zeng Shuai,Liu Qiang,Bi Maoqiang 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.4
The safe operation of power transformer is vital to the reliability of modern power network. The bushing is a key component of transformer that serves to connect the transformer windings to the transmission lines. Due to its intricate structure and severe operating conditions, the bushing is among the most frequent cause of transformer failure. Therefore, it is essential to monitor the condition of transformer bushing for maintaining the safe and stable operation of grid. In this paper, we propose a graphene piezoresistive pressure sensor based on handkerchief paper (GHPPS) to monitor the internal pressure of transformer bushing. The GHPPS possesses a highly porous structure and a fibrous tissue, and exhibits a superb sensitivity to the variations of bushing internal pressure. Moreover, we compared the sensitivity and conductivity of the sensors with different paper layers. The GHPPS with 8 layers owns the highest sensitivity (15.6 kPa−1), the smallest response time (60 ms) and recovery time (75 ms), and the best stability. In addition, a hierarchical alarm device is used to test the monitoring capability of GHPPS at different pressure levels. The results prove that the GHPPS is a promising tool for monitoring bushing conditions.
Wei Ji,Tianyan Shao 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.2
We propose a practical and fast finite element (FE) model updating method in which the response surface method and fmincon algorithm (FA) are used to modify the FE model of a new, improved box girder bridge with corrugated steel webs. Two three-dimensional FE bridge design models were compared to develop a reasonable initial FE model for updating this bridge. The response surface method (RSM) was used in our method for the optimal experimental design of the updated parameters, which were used as the basis of the numerical analyses performed to obtain the explicit relationships between the structural responses from the FE results and the parameters themselves. A comparison of the two optimisation methods — genetic algorithm and FA —revealed that FA provides more stable optimised results with higher efficiency. Using FA, parameters can be updated by minimising an objective function, which is constructed from residuals between measured and predicted structural responses using the expressed relationships. A numerical example of a simply supported composite girder was discussed to illustrate the effectiveness of our procedure. The method was applied to the FE model updating of the Jingzhong Bridge using in situ static and dynamic results; satisfactory agreement was observed between measured and predicted bridge responses.
A Cloud Service Model Based on Indirect Addressing
Guorong Chen,Tianyan Mao,Juli Deng,Xue Wu,Chengrun Ji 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.5
The cloud service is a new type service way to provide the users in distributed environment, but the service model, service package and the knowledge searching methods trouble it popularizing. Aiming at the problems, a cloud service model based on indirect addressing is proposed in the paper. It analyzed the new problems serving in cloud firstly, then comes out a recourse and service invoking model based on indirect addressing, gave out the service actors of the model in detail, studied the package method of the cloud interfaces, produce the knowledge step in the indirect addressing mode of resources distribution. Proposed a knowledge discovery strategy based on Chord ring to resolve the knowledge retrieval problem and introduced the Chord ring in detail. The case studies proved the method with some advantages, and it proposes a new way to resolve the service problem in cloud.
The drag characteristics prediction of multi-plate frictional wet clutches in vehicle transmissions
Minghui Zhang,Yanfang Liu,Tianyan Liu,Xiangyang Xu,Jin Xu,Yudong Zhang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7
The multi-plate frictional wet clutch is one of the most important components in automatic transmissions. With the increasing of the rotational speed, the phenomena is tested that the drag torque firstly increases to the peak torque, and then decreases to a lower level and maintains within a certain range, and finally increases rapidly again. A fluid-structure coupled model of the whole wet clutch was established. The simulation results show that the pressure distribution is obviously nonuniform either on the frictional surface or between two sides of the clutch plate. The nonuniform pressure would cause the axial and deflection motion and so the impact would occur, which is the main reason for the drag torque’s increasing under high rotational speed. Based on the simulated results, a prediction model was built with the direct artificial neural network method. The test results show that the drag characteristics prediction model is effective and fast.