Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/14573
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
摘要: 
水力為不具環境污染性的發電方式,而發電水路必須承受鉅大的內水壓力,為經濟因素考量通常以高張力之鋼材為材料,稱為壓力鋼管。基於設計及經濟考量,在沿水路上設置為數及型狀不一的分歧管,以發揮其經濟效益。因材料或施工不良等因素造成裂縫,將嚴重影響安全及使用年限,因此本文將針對壓力鋼管及分歧管含裂縫時,所發生的力學與挫屈問題進行探討;另為確保材料與工程品質的可靠性,亦將針對材料之選購、施工效率與績效分析,建立一套具學術基礎的分析模式。
經數值驗證證實本文所提出之無限小元素分析法,適用於含裂圓管、焊道及加勁板之挫屈分析。尤其可輕易分析扭曲裂縫的奇異性問題且此裂縫型式之裂縫增長速率高於其他型式。焊道裂縫垂直且終止於焊接交界面與垂直於長軸方向之奇異性階數分別收斂於0.499及0.545,而應力強度因子KI皆收斂於0.996。另所提出之綜合分析法,分析局部挫屈時,顯示極佳的分析效果,可輕易且細膩地,指出裂板之局部挫屈發生的次序。加勁板則因焊道裂縫,導致加勁效果降低,尤其焊道裂縫長度與加勁材長比為0.45時,加勁效果明顯降低。
為達高品質之工程水準,選擇優良鋼材與建立品質評估模式可確保工程品質,因此本文利用統計方法,分別建立簡便、有效且值得信賴的評估方法與程序;其中提出精確度指標、準確度指標與鋼材抗拉強度品質指標,評估鋼材之品質;另再提出多重製程能力分析圖,分析各種不同鋼材品質的優劣,以判斷整體鋼材品質;為達優異的工程品質,以焊接效率的單邊品質特性,推導及發展一客觀的評估工具,以評估焊接效率品質;為正確評估焊接技術人員及焊接機器的績效,以學理為基礎,推導出焊接績效指標的最佳估計式,其效益為可以提供營建工程單位正確且客觀地評估焊接技術人員與焊接機的焊接技術與績效。

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.
URI: http://hdl.handle.net/11455/14573
Appears in Collections:土木工程學系所

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