Papers by Author: Yun Wang

Abstract: Integrated with orthogonal design method and numerical simulation, injection molding process of the Y-type electrical connectors was conducted to study the influence of process parameters on volume shrinkage rate and maximum warpage, which are regarded as product quality indices. The multi-indices valuation model for the main influencing factors of the process is developed. The influencing sensitivity to the multi-objective of the processing parameters, such as melt temperature, mold temperature, injection time and holding pressure, is determined by range analysis. Through analyzing the diagrams of influential factors, the optimized process parameter diagram is obtained and verified by simulation. The optimum parameters minimizing the warpage defect and shrinkage are: melt temperature (528K), mold temperature (338K), filling time (0.6s), holding pressure (100%) and holding time (10s). The results show that it is effective to balance the impact of process parameters on the shrinkage and warpage. The work can provide optimal design and process reference for the quality control and assembly precision.

Abstract: The inner structure and defects of the silicon panel will influence the transfer efficiency and the stability of the polycrystalline solar cells, thus the non-destructive testing of the silicon panel is very important. In this paper, a Scan Acoustic Microscopy is applied to test the inner structure of polycrystalline silicon solar panel. From the grey image of C-Scan by the microscopy, the amplitude distribution of the bottom wave generated by the interaction between the inner grains of the polycrystalline silicon and the acoustic beam can be seen clearly. Furthermore, the defects as well as their size and position can also be tested by A-Scan, B-Scan and C-Scan with high resolution and high accuracy. The experiment results show that it is a good non-destructive method to test and evaluate the quality of the inner structure of polycrystalline silicon solar panel.

Abstract: The 3-D numerical model of wave tank is developed considering the effects of wave generating and absorbing based on viscous fluid motion differential equations (N-S equation) and the volume of fluid (VOF) method by the use of FLUENT solver. The simulation is also made by the analysis of the existing methods of wave simulation. The wave form of the 3-D wave tank is analyzed with the result of diverse diversification at different wave location and their relationship. The flow path of each particle of the wave during the propagation is also been analyzed, which provides guidance for the wave form analysis.

Abstract: With the rapid development of plastic products in the world and the increasingly sophistication of plastic technology, rotational moulding (RM), has become the most practical and irreplaceable way of producing the large and super large containers like tanks, tank, etc. Compared with injection moulding and blow moulding, RM has the characteristics of low cost and easy-to-use, and its application has been extended into many domains. The principle of rotational moulding and comparison of raw material by the requirement of rotational moulding is introduced. The paper emphasizes the introduction of state-of-the-art of RM equipment; also it points out the development of RM.

Abstract: With the rapid development of MEMS and electronic industry, the demands for micro-parts are increasing gradually. However, size effects make the traditional forming theories and deformation mechanism not suitable in micro forming field. In this paper, we introduced the classification of the size effects. It pointed out that the size effects can be divided into the first order and the second order size effects in the micro-forming. For the first order size effects, the theory model was established based on the surface layer model. It also clarified the phenomenon that flow stress of the blank reduced with the increase of the ratio of grain size and thickness (t decreases or d increases). Finally, the model was verified with the experimental results of the first order size effects in the references, confirming the effectiveness of the theoretical model. It provides a method to theoretically and experimentally study the micro-plastic forming.

Abstract: In this paper, the influence of grain size and blank hold force on micro deep drawing stress and displacement are studied by self-made device. The results show that drawing stress decreases and elongation rate increases with the increase of grain size, the concentrated force area of cylinder-shaped part is transferred from the area punch fillet to die fillet area. Twin grain ratio and twinning degree near the punch fillet are increasing. Twin grain distribution becomes uneven with the increase of grain size. In micro deep drawing, the displacement increases with the increase of blank hold force, meanwhile, forming stress almost remains constant. The flange wrinkling can be inhibited.

Abstract: The phenomena of green water are the maximum vertical extent of wave uprush over freeboard on the deck with the result of damage to the deck, bow and auxiliary equipment. The FPSO with Single-point mooring system or disconnectable mooring system always operates in the severe deepwater or ultra-deepwater environment such as Gulf of Mexico or Southeast Asia, which should be allowed to weathervane. Therefore, FPSO is always exposed to wave runup and overtopping. Nowadays green water problem has become one of the most important factors to endanger offshore structures, such as FPSO, TLPs and SPARS. This paper gives a comprehensive review of the state-of-the-art in green water, including the forming mechanism, numerical simulation and model test of wave runup. Finally the prospect of simulating green water is discussed.

Abstract: Advanced offshore floating structure utilizes dynamic positioning system to guarantee its automatic positioning without mooring system, realizing the offshore positioning requirements. The thruster is the key component of DP whose installation method directly affects the operation of DP and positioning accuracy of offshore floating structure. Based on the analysis of underwater installation methods of the existing large equipment, the paper proposes a new installation method of the large thrusters, using the L-shape floating platform as shift, orientation and position adjustment of thrusters. The new method can complete the precise position matching and installation of thrusters in the bottom of the structure.

Abstract: A new robust structured light technique based on multi-valued pseudo-random color encoded pattern is discussed in this paper. After analyzing the advantages and disadvantages of the existing pseudo-random coding patterns in computer vision, a new multi-valued pseudo-random color encoded pattern is designed on the basis of the combination of the feature points and the feature lines. Using this pattern, the feature points are easy to extract, and the problems of leaking points and pseudo-feature points are greatly reduced. Furthermore, it also reduced the difficulty and the complexity of the feature matching because of the feature lines.

Abstract: Conventional FDSO (Floating Drilling Storage Offloading) construction method which needs particular dock and berth has limitation in application. A new block construction method for FDSO without dock and berth is offered in this paper based on the analysis of present FDSO block construction method. In this method, semi-submersible barge is utilized as a closure construction platform. The process includes the following stages: pre-segmentation closure, set limit and positioning components, separate the block from semi-submersible barge after block launching, rotate block with 90 degree and complete block construction. With the advantage of high assembly precision and small flatness adjustment, the presented method is especially suitable for cylinder FDSO’s close construction without large dock and berth.