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標題: 壓力鋼管與Y型分歧管之加勁板破裂狀況及工程品質評估之研究
Study on Cleavage Analysis and Quality Assurance for Penstock and Stiffening Plate of Y-Branch
作者: 宋文沛
Sung, Wen-Pei
關鍵字: infinitely small element;無限小元素;Cleaverage analysis;weld line with crack;Best Estimators;Evaluation Procedure;Quality Assurance;破裂分析;焊接裂縫;最佳估計式;評估程序;品質評估
出版社: 土木工程學系

Hydroelectric engineering never causes pollution of environment. Waterway of hydroelectricity generally is under significant pressure of internal water. The high tensile strength of steel plate is used as constructional material of waterway, called as penstock, for the economical consideration. In order to bring exploitative benefit into full play, the various quantity and types of bifurcation are set up on the basis of design and economical consideration. The cracks, induced by the defects of material or bad construction, affects the safety and endurance of hydroelectric power plant. Thus, this paper is probing into mechanics and buckling problems resulted from the mechanics phenomena of penstock and bifurcation with crack. Furthermore, in order to ensure the reliability of material and construction quality of penstock and bifurcation, a set of analytical methods are set up for evaluating the quality of material, constructional efficiency and performance.
The numerical verification of infinitely small element analysis method, proposed in this paper, confirm that these methods are suitable for analyzing the stress intensity factor of penstock and weld line with crack. The proposed method combined with finite difference method is really useful for analyzing the buckling sequence of stiffened plate with crack. Especially, this method can easily analyze the problem of kinked crack that the crack growth rate is higher than the other crack types. The singular orders of crack vertical on weld line and along long axis are 0.499 and 0.545 respectively. The stress intensity factors KI are converged to 0.996. This synthetic method provides a convenient technique for solving cracked plate problems and can definitely locate the local buckling zones. Especially, the sequence of local buckling zones can be pointed out easily. In accordance with the crack on weld line of stiffening plate, the stiffening efficiency will be dropped obviously.
To achieve the high engineering quality, the quality evaluation model is established to ensure the superior steel material and engineering quality. A whole set of easy ways and procedures for construction industries to evaluate the quality of hydroelectric power plant based on principles of statistics is proposed in this paper. Where the indices of precision, accuracy degree and tensile strength of steel are used to evaluate the quality of steel. Separately, the multi-process capability analysis chart is proposed to analyze the quality of various types of steel material for judging the quality capability of ironwork. In order to attain the excellent engineering quality, the unilateral quality property of weld efficiency is used to derive and develop an objective evaluation tool. A systematic and practical evaluation method for welding performance is contributive to control and manage quality and performance of weld. Therefore, a set of evaluation method is proposed in this paper to judge the performance of welding operator and welding technician. The characteristic of this research proposes a new skeleton of index of welding performance to adopt explicit quantity expression to calculate this index. A set of hypothesis inspection procedure is proposed to examine the welding performance of welding operator and welding technician that is the basis of substantial theory.
Appears in Collections:土木工程學系所

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