Papers by Author: Zheng Yi Ren

Abstract: The three-dimensional finite element model of 600 Wh energy storage flywheel rotor system supported by active magnetic bearing (AMB) was built with the commercial software ANSYS to carry out the modal analysis. The modeling method of the AMB and their effect on the rotor system are explored. Modal analysis was performed, and the modal shapes of the rotor system were obtained. The Campbell diagram calculated by ANSYS was gained to be compared with the one calculated by the theoretical dynamics model. This research provides a theoretical basis for the rotor system design. The ideas and methods can be used as a reference for the study of dynamic characteristics of the rotor system and direct the flywheel prototype future design.

Abstract: The basic working principle of a Flywheel Energy Storage System (FESS) is introduced. From the angle of failure detection means and fault types, the status and deficiency of the research on FESS Fault Diagnosis (FD) and Fault Tolerant Control (FTC) are reviewed. Moreover, the FESS FD and FTC methods are analyzed in detail. Finally, the deficiency, research hotspot and development trends of FESS FD and FTC are discussed.

Abstract: In this paper, considering the material properties of the composite flywheel and the characteristics of the pre-stressed structure, stresses and strains induced by rotor rotation and interference fit were calculated by finite element (FE) method based on the plane stress hypothesis, in the commercial software ANSYS. Based on the given material properties and the main dimension with a certain speed of rotation, three 2D FE-models of hybrid composite flywheel rotors with two-layer rotor structure were built with the unit property of plane stress, axisymmetric and plane strain respectively. Followed, the radial stress, circumferential stress and radial displacement of the rotor were obtained. The three simulation results are almost accordant with the present theoretical results. It shows that the numerical analyses are reliable. It can be shown that is advisable to design and optimize the flywheel rotor.

Abstract: The self-oscillation device has many advantages and is therefore suggested to be used in the pipeline supercharger. Simulation and analysis on the pressure-increasing effect of the pipeline supercharging caused by self-oscillation cavity were carried out by finite element method. The cavity structure of self-oscillation device was designed using the fluid network theory, natural frequency calculation, resonance conditions and Large Eddy Simulation Theory. A series of flow field distribution chart of the self-oscillation cavity were obtained. Results validate that the self-oscillation device is effective to increase the pressure of the pipeline supercharger. The relation curves of pressure-increasing effect with different structure parameters of the cavity were further analyzed. Previous experimental results are accordant with the present simulation results. It shows that the numerical analyses are reliable.

Abstract: Impact line is one of important factors to affect the shape accuracy and surface quality of auto body panel design and manufacture. It is difficult to study because of the complexity shape of auto body panels. The system of test analysis on impact line is established by analyzing the shapes and forming processes of auto-body panels, of which based on hyperboloid shallow shells. The criterion and research technique of impact line are introduced. Extensive experiment results, which show the effects of forming process conditions, such as blank holding force, draw bead arrangement, and lubrication on impact line, are achieved. It can be concluded that the draw bead arrangement significantly influence the impact line, the displacement of impact line is different with difference of blank holding force and the friction coefficient.

Abstract: Fracture behavior and the microstructure of Ti3AlC2 ceramics prepared by SHS/PHIP method were studied. Stress-strain curves at different temperature with a strain rate of 1×10-3 s-1 were obtained. Fracture toughness, flexural strength, crack propagation behavior and compressive deformation of specimens were investigated. Results show that the microstructure of the large size Ti3AlC2 ceramics prepared by SHS/PHIP method has typical layered feature of ternary carbide compound. The bridge-link phenomena induced by the flaky grains occurred in three-point bending test. It restrained the crack propagation and improved the fracture toughness of the material. Cylindrical specimens under axial compression usually smashed into chips for most of the ceramics materials, however, for the Ti3AlC2 ceramics prepared by SHS/PHIP, shear fracture along 45º incline of the specimen occurred at room temperature, and bulging deformation without any crack exhibited when temperature was high. It is concluded that the Ti3AlC2 ceramics prepared by SHS/PHIP has better fracture-resistance properties.

Abstract: An expert system in fatigue and fracture analysis based on Web is developed in this paper. The system consists of six functional parts: a general inference engine, some knowledge bases, a context, an interpretation engine, a bases administration system and the interface (includes browser, Web-server, etc.). It can simulate a human expert to make analysis and design scheme for some typical structural components: pressure vessels, huge rotation constructions, welded structures, etc. It is an open system which may be broadened and perfected to cover a wider range of application through the modification and enlargement of the knowledge and data bases on Web.