The final goal of this study is to apply a shock absorber based on plastic deformation of aluminum tube to an elevator buffer. First, in order to study characteristics of axially crushed tubes, various aluminum tubes were compressed on four types of dies. As a result, these caused the three modes of progressive buckling, tearing and inversion. It is concluded that the load-displacement curve of the inversion mode has ideal shape as shock absorber and its inversion load depends on the thickness of the tube. Secondly, energy absorbing mechanism of inversion mode was made clear with finite element method (FEM), and its details show two kinds of energy, frictional dissipation and plastic dissipation produced by meridional bending and circumferential stretching. A theoretical expression for calculation of the inversion load is derived from the virtual work theorem, the prediction from which agrees well both results of experiment and FEM. It is also discrived that use of molybdenum disulfide improves reproducibility of the inversion mode and its load-displacement curve.
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