POSTBUCKLING CHARACTERISTICS OF THE SHORT SUPERELASTIC SHAPE MEMORY ALLOY COLUMNS- EXPERIMENT AND QUANTITATIVE ANALYSIS

A few unique buckling and postbuckling characteristics of short superelastic shape memory alloy (SMA) columns are observed experimentally and explained in terms of numerical simulation. Interestingly, it is found from the load-deformation curves that during compression the SMA column with slenderness ratio ( ) k L of 38 exhibits two distinct buckling loads, the other one being higher, completely contrary to the general notion that load falls off monotonously for all columns in the postbuckling region. Similarly, for k L of 28, the SMA column can sustain a significantly high load after a distinct change in the mode of deformation. Based on the large deformation theory as well as the nonlinear stress-strain relations, the load-deformation curves of the short SMA columns have been predicted by using the FEM code ANSYS. Precise and quantitative analyses of these results verify the fact that the SMA column’s behavior can be attributed to the special nature of the stress-strain curves.