形状記憶合金で作られた柱の座屈現象について : 第1報, 曲り柱の座屈と双晶変形の効果

概要

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The research described in this paper grew from the serendipitous discovery of the TD (Twinning Deformation) effect, which was discovered by the first author. The experiment involved a SMA column (Ti-40.8% Ni-9.9% Cu, diameter 5 mm, length 50 mm) which was plastically deformed into a cosine wave with a peak-to-peak amplitude of 1.9 mm. The cylinder was then compressed from either end. As the compressive force was increased, the column because straighter, until it finally buckled at 19 kN. The buckling load of the curved columns is the same as that of the straight one. In this research, numerical analysis was performed on the distributions of stress and deformation of the SMA beams under compression and the underlying mechanism of the two phenomena was explained. Analysis of the anti-buckling effect involves a theoretical treatment of Non-Euler buckling. One way of explains the buckling mechanism is to consider the moment-deflection ratio as a spring constant. When the spring constant become negative, the column will buckle. The result of this calculation is in good agreement with experimental buckling loads. In analysis of straightening beams, it is assumed that the column had been bent to the shape of a perfect cosine wave from 0 to 2 π. And based on the same calculations as the anti-buckling analysis, the neutral fiber (or structural center) of the curved column was also calculated.
社団法人日本機械学会の論文
2001-07-25