Accounting for quasi-superelastic phenomena observed in a certain shape memory alloy

Date of Completion

January 2005


Engineering, Mechanical|Engineering, Materials Science




In research, investigating the properties of 5% Cu-Ni-Ti alloy, it was observed that this material exhibited unusual and potentially valuable aspects of behavior. For example, it was noted that under certain conditions, the material displayed a strong austenitic shape memory and also unusual superelastic properties. These observations suggested that the creation of long sought after devices that can be used in overcoming severe vibration problems in machinery may now be possible. This includes the avoidance of fatigue failure through damage accumulation and development of means to escape the effects of a sustained forced resonance. The unique properties, offering such promise, are referred to herein as quasi-superelasticity, produced when the material temperature is close to its Md value and thus where stress-induced phase transformation is limited. It is from these limitations that the desirable properties are derived. The possibility of creating a means to exploit them has prompted creation of this thesis, which concerns development of necessary tools to this end, i.e. an understanding of the causes and effects of quasi-superelasticity and from this, constitutive equations to emulate the unusual behavior the particular alloy provides. ^