Superelastic NiTi-alloys under torsional loading

Abstract
The paper presents experimental results on the mechanical behaviour of superelastic NiTi-shafts under torsional cyclic loading. Subject of the studies was to investigate the influence ofheat treatment, load amplitude and number of cycles on the fatigue and damping properties. Two solid and two hollow shaft samples in two different heat treated conditions were examined. The experiments show, that during load controlled cycling the transformation stresses and strains as well as the austenite shear modulus decrease with proceeding cyclic loading. In addition, the specific damping capacity values decrease and reach a minimum value after a certain amount of cycles before they slightly rise again.