| Summary: | 碩士 === 高苑科技大學 === 機械與自動化工程研究所 === 97 === This study is aimed at the static axial compression and dynamic axial impact tests to probe into the buckling behavior of mild steel circular tubes. All the tubes suffer, statically or dynamically, pure compression before buckling. And the buckling mechanism is either local crushing or global buckling. The number of crushing wrinkle increases as the striking energy increasing. The deformation mechanism is affected by the slenderness ratio as well. When the slenderness ratio is greater than about 13, the tube suffers global buckling regardless of static compression or dynamic impact, and the buckle takes place in the plastic region. With the same impact energy, The Location of initial crushing at alters with the axial length of the tube, While the total axial displacement is not affected by the axial length of a tube.
A groove (imperfect) effectively affects the buckling behavior of a circular tube. When the minimum interval between the groove and one end of the tube is greater than a critical value, the tube suffers local crushing as well as global buckling at the groove. In order to get insight into the buckling mechanism of a circular tube, the crystal grain is inspected by melallographic test. The bending area of local crushing or global buckling apparently suffers serious grain deformation, while the grains in the other region almost not deform. It is revealed obviously that the stress distribution is much nonuniform when a tube is at the moment of buckling.
|
|---|
