臺灣博碩士論文加值系統

本文主要在研究柱及殼結構在常溫下的潛變挫屈行為。在實驗方面，先以單軸拉伸實驗測量材料的常溫機械性質，並設計一組設備測量材料在不同應力作用下的潛變行為，再以應變硬化方程式(Strain-hardening equation)與修正型時間硬化方程式(Modified time-hardening equation)描述材料的潛變行為。在分析方面，以有限單元分析軟體ANSYS分析柱及殼結構之潛變挫屈變形行為及臨界時間。結果顯示，紅銅材料在常溫有明顯之暫態潛變行為，且受到的負載愈大，潛變行為愈明顯；以應變硬化方程式和修正型時間硬化方程式可以合理地描述紅銅之潛變行為；以ANSYS分析殼結構受側向壓力之結果與文獻記載相符；柱體受到的負載愈大則發生潛變挫屈的時間愈短；柱與殼結構之潛變挫屈行為對於幾何不完美十分敏感。

The creep buckling behavior of column and shell structures at room temperature was investigated. In experiment, the mechanical properties of test structures were measured by tensile test. An experimental setup was designed to measure the material creep behavior at different stress levels. The material creep behavior is described by the strain-hardening equation and modified time-hardening equation. In analysis, the creep deformation and the corresponding critical time at creep buckling for column and shell structures were analyzed by finite element code ANSYS. The results showed that copper had apparent transient creep behavior, and copper deformed more for higher loading. The creep behavior of copper can be described well by the strain-hardening equation and modified time-hardening equation. The analytical results of critical time at creep buckling for columns became shorter as higher loading was applied. The creep buckling behavior of column and shell structures are very sensitive to geometry imperfection.

頁次
摘要…………………………………………………………………. I

誌謝…………………………………………………………......…… III
目錄…………………………………………………………………. IV


圖表目錄……………………………………………………………. VI
第一章 簡介……………………………..…………………………. 1
1.1 研究動機………………………...………………………….. 1
1.2 文獻回顧………………………...………………………….. 1
1.3 研究主題…………………………..……………….……….. 7
第二章 潛變挫屈分析……………..…………………………. 8
2.1 有限單元潛變分析…..………….………………………….. 8
2.2 幾何模型與邊界條件.………………………....…………… 12
2.3牛頓拉夫森法..……………………....……………………… 13
2.4 挫屈分析流程…………..……....………….……………….. 14
2.5 潛變挫屈分析流程….…....…………………………………
14
第三章 實驗程序…………………………………………………… 15
3.1 試片製作…………………………………………………... 15
3.2 單軸拉伸實驗………………………………………………. 15
3.2.1 單軸拉伸實驗步驟………………………….….…..… 15
3.2.2 柱體挫屈實驗步驟.…………….…………………..… 16
3.3 單軸拉伸潛變實驗…………...……………………….……. 16
3.3.1 單軸拉伸潛變實驗步驟……………..……………..…
17
3.3.2 材料潛變常數計算…………..……………………..…
17
3.4 潛變挫屈實驗………..………………………………..……. 18
第四章 結果與討論…………………………………………………論…………………………………………………..論………………………………………………… 19
4.1 單軸拉伸實驗結果…………………….……………………度…………………………….度…………………………………… 19
4.2 單軸拉伸潛變實驗結果……..………………………...……
20
4.2.1 應變硬化方程式參數…………..……...……….………
20
4.2.2 修正型時間硬化方程式參數…………..………………
22
4.3 挫屈分析與實驗..…………………………………...………
22
4.4 彈性柱體潛變挫屈分析……...…….…………….…………
23
4.4.1 不同時間增量..………………………………………… 23
4.4.2 不同單元數量..…………………………………………
24
4.4.3 柱體負載與臨界時間之關係..…………………………
25
4.4.4 不同楊氏模數與臨界時間之關係…………………..… 25
4.5 非線彈性柱體之潛變挫屈分析與實驗………………….… 26
4.5.1柱體臨界負載與時間之關係…………………………… 26
4.5.2 幾何不完美對柱體潛變挫屈行為之影響……......…… 26
4.5.3 長度為100mm柱體之潛變挫屈行為……………….… 27
4.6 圓柱殼挫屈分析..…………………………………...………
27
4.7 圓柱殼潛變挫屈分析..…………………………...…………
27
第五章 結論………………………..……………………………….. 29
參考文獻……………………..……………………………………… 30
圖表…………..……………………………………………………… 33

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