Flextural behavior of martensite Ni-Ti beams

In this work, bending equations of prismatic SMA beams in martensite phase and at low temperature is derived analytically and verified by experimental tests. A onedimensional model having asymmetric response during tension and compression has been proposed. In this model, elastic modulus depends on the progress of martensitic phase transformation and martensite twined and detwinned phases have different material parameters. In addition, in martensite detwinned phases favored by tension and compression, the slopes of loading and unloading are completely diverse. According to the pure bending solution as well as considering semi-analytical methods, we obtain general bending equations of an SMA beam based on the pure bending solution. Using polynomial approximation functions, the relationship between deflection and length has been obtained. We have conducted three- and four-point bending tests for rectangular as well as circular SMA beams. A reasonable accuracy between analytical results and experimental data is obtained in this paper.

Keywords:

Shape memory alloy , Tension-compression asymmetry , Bending behavior , and Prismatic beams.