Load-induced local phase transformation and modulus of shape memory alloys under spherical indentation by finite element method

Spherical Indentation Hardness of Shape Memory Alloys

Analysis of spherical indentation of superelastic shape memory alloys

Dimensional analysis and the finite element method are applied in this paper to study spherical indentation of superelastic shape memory alloys. The scaling relationships derived from dimensional analysis bridge the indentation response and the mechanical properties of a superelastic shape memory alloy. Several key variables of a superelastic indentation curve are revealed and examined. We prov...

Oliver–Pharr indentation method in determining elastic moduli of shape memory alloys—A phase transformable material

Instrumented indentation test has been extensively applied to study the mechanical properties such as elastic modulus of different materials. The Oliver–Pharr method to measure the elastic modulus from an indentation test was originally developed for single phase materials. During a spherical indentation test on shape memory alloys (SMAs), both austenite and martensite phases exist and evolve i...

TRANSFORMATION BEHAVIOR OF NiTi SHAPE MEMORY ALLOYS TREATED BY THERMOMECHANICAL PROCESSING USING DSC

Abstract: In the present study the effect of thermomechanical treatment (cold work and annealing) on the transformation behavior of NiTi shape memory alloys was studied. Differential scanning calorimetry was used to determine transformation temperature and its relation to precipitates and defects. Three alloys including Ti-50.3at.% Ni, Ti-50.5at.% Ni (reclamated orthodontic wires) and 50.6at...

Finite-element-simulations of polycrystalline shape memory alloys

Shape memory alloys (SMA) are widely employed as sensors and actuators. The need for precise control requires reliable modeling techniques involving, e.g., prescribed stresses and temperatures. These parameters are always inherently coupled in SMA. Various models are in use to characterize the non-linear hysteretic behavior of SMA; among them some that do not provide a means to incorporate true...