蘇侃Hon-So臺灣大學:機械工程學研究所陳松男Chen, Sung-NanSung-NanChen2010-06-302018-06-282010-06-302018-06-282009U0001-1301200915184800http://ntur.lib.ntu.edu.tw//handle/246246/187266本文以10mm V槽深與4mm V槽深之薄鋼板進行高速(9m/s)動態壓縮試驗，同時以顯性動態元素法LS-DYNA進行模擬，以探討其動態挫曲發生的初始原因。 在實驗中發現，10mm V槽深薄板在挫曲時(力量達到最大值)V槽會被拉開，因而使得其軸向剛性降低，導致所得之臨界荷重與4mm V槽深接近。其塑性挫曲是由V槽局部區域發生變形所引起，最後發展至整片試片。而4mm薄板在挫曲時V槽並沒有被拉開的現象，因此其臨界荷重仍可保持一定大小，因為其挫曲是整個薄板一起發生挫曲，因此稱其為整體挫曲。 在數值模擬中發現，10mm V槽深薄板與4mm V槽深薄板也有上述的現象，10mm V槽被拉開而4mm V槽無甚變化，但是模擬的變形過程整齊且對稱，這是因為在模擬中材料可達到均質的特性，但實驗中無法達到，所以模擬和實驗無法完全相同。This article focuses on the deformation of thin plates with V-grooves in high speed dynamic compression test. The depth of the V-grooves was set at two depths: 4 and 10mm, and the ram speed during the test was set at 9m/s. The simulationa was conducted by using the dynamic-explicit FEM code LS-DYNA. From the experimental results, it was found that the deformation occurred at grooves 10mm depth when buckling started. Since the buckling was accelerated by the deformations around the V-groove regions, such phenomenon was considered as the local deformation inducing buckling. However, there was no local deformation at grooves 4mm deep as buckling started; the critical load at this condition was the same as in the condition with V-grooves 10mm deep. Since the buckling was induced by the deformation of the entire plate, it was called as global buckling. The above phenomenon was also found in simulation. The deformation occurred on grooves 10mm deep while the grooves 4mm deep remained the same. However, the deformation in simulation was regular and symmetric. This was due to the assumption on the material that was homogeneous and isotropic. The plates used in the experiments were not made of homogeneous materials, thus the deformation in experiment was not completely the same as those from simulation.口試委員會審定書....................................................Ⅰ文摘要............................................................Ⅱ文摘要............................................................Ⅲ錄................................................................Ⅴ表目錄............................................................Ⅷ號說明............................................................XI一章 緒論..........................................................1 1-1 研究動機與目的................................................1 1-2 文獻回顧......................................................2 1-3 本論文之結構..................................................4二章 實驗之相關理論................................................5 2-1 細長柱之彈性挫曲與塑性挫曲....................................5 2-1-1 彈性挫曲..................................................5 2-1-2 塑性挫曲..................................................9 2-2 金屬薄板之挫曲...............................................12 2-2-1 靜態挫曲.................................................12 2-2-2 動態挫曲.................................................12 2-2-3 板片挫曲理論簡介.........................................13 2-2-4 理想板片挫曲.............................................15 2-3 形狀因子之影響...............................................19 2-4 塑性變形理論.................................................19 2-4-1 降伏準則.................................................19 2-4-2 塑性狀態.................................................21 2-5 加工硬化.....................................................21 2-6 塑性波.......................................................23-7 高應變率下的塑性變形.........................................25三章 實驗.........................................................27 3-1 儀器設備.....................................................27 3-2 材料試片.....................................................31 3-3 實驗模型.....................................................32 3-4 實驗操作步驟.................................................32 3-5 實驗結果.....................................................34四章 模擬.........................................................42 4-1 LS-DYNA 操作流程暨軟體架構...................................43 4-2 前處理.......................................................43 4-2-1 幾何過程.................................................43 4-2-2 網格化過程...............................................44 4-2-3 材料性質.................................................45 4-2-4 邊界條件.................................................46 4-3 顯性和隱性求解概論...........................................46 4-3-1 顯性求解方式.............................................46 4-3-2 隱性求解方式.............................................47 4-3-3 隱性和顯性求解方式比較...................................48 4-4 模擬結果.....................................................48五章 實驗與模擬結果討論...........................................53 5-1 挫曲方式.....................................................53六章 結論與建議...................................................55 6-1 結論.........................................................55 6-2 建議.........................................................55考文獻............................................................576923185 bytesapplication/pdfen-US動態挫曲臨界荷重局部挫曲整體挫曲均質Dynamic bucklingCritical loadLocal bucklingGlobal bucklinghomogeneousthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/187266/1/ntu-98-R95522521-1.pdf