Papers by Author: Jung Chung Hung

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Authors: Jung Chung Hung, Ching Shyong Shieh
Abstract: This study attempted to design and develop an integrated system of a microforming apparatus with ultrasonic-vibration device. A closed-loop displacement and force control was implemented with servo motors. The apparatus has a load capacity up to 10,000N. The displacement error curve of the platform was measured with API 5DLS laser interferometer, and fed into the control program to compensate for motion errors. The positioning precision of the platform has been upgraded up to 5μm, with a load accuracy of 0.5N. Taking advantage of FEA and optimization technology, boosters and resonator with 35 kHz frequency were designed and fabricated. The simulation results and the experimental results match perfectly on the account of resonance frequencies and amplitudes. To the end, the integration of the ultrasonic-vibration device with microforming platform demonstrates a precision process for micro-parts.
4092
Authors: Dyi Huey Chang, Jung Chung Hung
Abstract: Light and thin bipolar plates are essential in increasing the power density of a fuel cell. To construct high-aspect-ratio micro flow channels in such plates is, however, a big challenge. This study reports on machining micro flow channels in metallic bipolar plates using micro electrical discharge machining milling (micro EDMM) with a tungsten carbide electrode. We successfully machined metallic bipolar plates with 500μm channel and rib widths, height of 600μm in a reaction area of 20mm × 20mm, on 1mm thick of SUS316L stainless steel. The optimal operating parameters were explored and discussed. The performance of resulting fuel cell (Metallic-FC) was compared with a commercial available fuel cell composed of graphite bipolar plates (Graphite-FC). The high temperature of Metallic-FC increases its electrochemical reaction rate and consequently yields higher power density (723 mWcm-2) then that of Graphite-FC (687.3 mWcm-2)
1237
Authors: Jung Chung Hung, Yen Pin Tsai, Ching Hua Hung
Abstract: This research integrated finite element analysis (FEA) and optimum design to obtain a fast, accurate and automatic optimization system for the design of an ultrasonic horn. The optimization system was developed to achieve uniform amplitude distribution on the output surface of a block shaped horn for the ultrasonic plastic welding. Agreement between the experimental and numerical data proved that this optimization system was efficient in the design of ultrasonic horns.
278
Authors: Ching Hua Huang, Ching Hua Hung, Jung Chung Hung, Chia Rung Lin
Abstract: The aim of this research is to investigate numerically the neck-spinning process of a tube at elevated temperature. The commercial software Abaqus/Explicit was adopted in the simulation. For the construction of the material model, special uni-axial tensile tests were conducted at elevated temperature and various strain rates, since the material is sensitive to strain rates at high temperature. The influence of the element type and mass scaling factor were investigated through numerical simulation. Full-integration shell element is the better choice in the simulation of the neck-spinning process at elevated temperature. The use of suitable mass scaling factor will make the analysis more efficiency. Comparisons between experimental and simulation results on thickness distribution and the outer contour of the spun tube are discussed. Good agreement was found between experimental and simulation results.
2708
Authors: Chi Chen Huang, Hsin Yen Fan, Ching Hua Hung, Jung Chung Hung, Chia Rung Lin
Abstract: Tube spinning is a metal forming process used to manufacture axisymmetric products. This study chose a seamless thick-walled steel tube to manufacture a high pressure vessel. Finite element analysis was successfully applied to the neck-spinning process of a thin-walled tube; however, previous research has not investigated the neck-spinning process of thick-walled tubes. Therefore, the aim of this research was to investigate numerically the neck-spinning process of thick-walled tubes at an elevated temperature. The commercial software Abaqus/Explicit was adopted in the simulation. This paper compares experimental and simulation results on thickness distribution and outer contour of the spun tube. During the final stage, the average deviations between the simulation and experiment were 6.74% in thickness and 4.97% in outer contour. The simulation results correspond with those derived in the experiment.
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