- 學位論文
具V型槽薄鋼板之動態挫曲初始原因探討
The study on how the dynamic buckling of thin steel plates with V-grooves starts
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摘要
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。
並列摘要
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.
參考文獻
[1] 陳振堂,V型槽對薄鋼板之動態挫曲特性之影響,國立台灣大學機械工程研究所博士論文,2006.
[5] H. Kolsky, Proc. Phys. Soc. London, 62B, pp.676-700, 1949.
[6] J.D. Campbell, Dynamic plasticity: macroscopic and microscopicaspects, Mater. Sci. AndEng., 12, pp.3-21, 1973.
[7] Theodore von Karman and Pol Duwez, The Propagation of Plastic Deformation in Solids, J.Applied Physics., pp. 987-994, 1950.
[8] M. Langseth and O.S. Hopperstad, Static and Dynamic Axial Crushing of Square Thin-walled Aluminium Extrusions, J.Impact Eng., 18, pp. 949-968,1996.