Shape Memory Alloys Behaviour: A Review

Abstract

Shape memory alloys are used in a variety of fields, such as medical or aeronautical. Other fields of knowledge have been researching these materials, attracted by their capacity to dissipate energy through high-strain hysteretic cycles without significant residual strains. Because of these interesting properties for seismic protection, an example of the possible beneficiaries of these materials are civil engineering structures. This paper reports a bibliographic review on the characteristics and uniaxial macroscale constitutive models for shape memory alloys, of interest for a significant number of applications, most often based on wires and bars. The constitutive model assessment focuses on mechanical and kinetic laws, as well as on the energy balance law, of relevance for dynamic loadings. Some characteristics of these materials are still not sufficiently well known, especially those related to ageing. With regard to behaviour prediction, the most frequently used uniaxial constitutive models result in similar responses.

Studies on the Two-Step Aging Process of Fe-Based Shape Memory Single Crystals

“…Precipitates being too small or too large can result in dislocation cutting (Friedl mechanism) or in the formation of Orowan loops around the precipitates. Both mechanisms are associated with plastic deformation which lowers the resistance to cyclic degradation [18][19][20][21][22][23]. Therefore, it is of great interest to find an optimal heat treatment which would allow one to control the precipitate size, their distribution and the volume fraction .…”

Vibration Control of a Flexible Beam with Embedded Shape Memory Alloy Wire

“…Shape memory alloys are defined by their ability to "remember" a set shape and transform to this shape after deformation through a solid-solid phase change. The material's ability to produce work over large areas without producing residual strains makes it a popular research topic in mechanical, medical and aeronautical fields [12]. The material starts off in a Martensite phase where it is soft and deformable.…”

Effects of Thermomechanical Treatment on Phase Transformation of the Ti50Ni49W1 Shape Memory Alloy

“…The thermoelasticity of SMAs relies on the B2 ↔ 19' martensitic transformation behaviors, which can be influenced by heat treatments and plastic deformations, such as thermal cycling [2], aging treatment [3,4], and cold rolling [5]. Moreover, the martensitic transformation of TiNi SMAs is also affected by the addition of other elements.…”