Shape memory effect based thermal cycling induced flexoelectricity for energy harvesting

2021 ◽  
Vol 194 ◽  
pp. 113701
Author(s):  
Zhiqiang Zheng ◽  
Ping Huang ◽  
Fei Wang
Keyword(s):  
Energy Harvesting ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect

Thermal cycling stability and two-way shape memory effect of Ni–Cu–Ti–Hf alloys

2001 ◽  
Vol 119 (6) ◽  
pp. 381-385 ◽  
Author(s):  
X.L. Liang ◽  
Y. Chen ◽  
H.M. Shen ◽  
Z.F. Zhang ◽  
W. Li ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Cycling Stability

The effect of preliminary thermal cycling under load on the magnitude of the deformations driven by the shape memory effect

2019 ◽  
Vol 85 (7) ◽  
pp. 55-63 ◽  
Author(s):  
Ivan N. Andronov ◽  
Irina V. Churilina ◽  
Sergei V. Kryuchkov ◽  
Nikolai P. Bogdanov
Keyword(s):  
Thermal Cycling ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Logistic Model ◽  
Martensitic Transition ◽  
Noticeable Increase ◽  
Maximum Value ◽  
Cylindrical Samples ◽  
Martensite Inelasticity

Results of the experimental study of the effect of preliminary thermomechanical impact (TMI) via thermal cycling under load on the deformations attributed to the shape memory effect (SME) are presented. Two modes of TMA were studied: i) thermal cycling under constant loads, the values of which were sequentially increased to the level of the maximum value; and ii) thermal cycling under constant loads, the values of which are successively reduced from the level of the maximum value to zero. Smooth cylindrical samples with a length and diameter of the working part 33 and 4 mm, respectively, made of TN-1 alloy with characteristic martensitic transition temperatures were used. The experiments were carried out in the mode of thermal cycling through the intervals of martensitic transitions at a constant value of torque. It is shown that thermocycling in conditions of mode (i) leads to a monotonic growth of the SME induced deformations, whereas subsequent thermocycling at the same load in conditions of mode (ii) leads to a noticeable increase in the SME induced deformations. A logistic model of the phenomena of martensite inelasticity observed in the materials with shape memory effect is proposed on the base of the Verhulst logistic equation which provides a fairly accurate description of the material deformation during all the stages of thermal cycling. A computational-experimental method has been developed to take into account the effect of a preliminary thermomechanical impact on SME induced deformations.

Molecular dynamics simulations of the two-way shape-memory effect in NiTi nanowires

2015 ◽  
Vol 1782 ◽  
pp. 35-40
Author(s):  
Prashanth Srinivasan ◽  
Lucia Nicola ◽  
Barend Thijsse ◽  
Angelo Simone
Keyword(s):  
Molecular Dynamics ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Molecular Dynamics Simulations ◽  
Compressive Stress ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Austenitic Phase ◽  
Dependent Behavior ◽  
Dynamics Simulations

ABSTRACTShape memory alloys (SMAs) exist in different phases depending on temperature and stress level. Experimental evidence shows that SMAs oscillate between two shapes during thermal cycling. This phenomenon, known as two-way shape-memory effect, occurs due to a transformation between the austenitic phase and the martensitic phase. The two-way shape-memory behavior is studied here by molecular dynamics simulations in NiTi nanowires of different diameter to understand the effect of loading on the size-dependent behavior. Thermal cycling is performed while holding the system at zero stress and at a fixed compressive stress. At zero stress, the martensite structure formed on cooling depends on the wire diameter. However, when cooling is performed at a sufficiently large constant compressive stress, the formation of a single martensitic variant is observed for all diameters.

Tensile Failure of 55-Nitinol Wire

1975 ◽  
Vol 33 ◽  
pp. 46-47
Author(s):  
F. I. Grace
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Stoichiometric Composition ◽  
Tensile Failure ◽  
Initial State ◽  
Initial Shape ◽  
Nitinol Wire ◽  
Cscl Type ◽  
Shear Transformation

An interest in NiTi alloys with near stoichiometric composition (55 NiTi) has intensified since they were found to exhibit a unique mechanical shape memory effect at the Naval Ordnance Laboratory some twelve years ago (thus refered to as NITINOL alloys). Since then, the microstructural mechanisms associated with the shape memory effect have been investigated and several interesting engineering applications have appeared.The shape memory effect implies that the alloy deformed from an initial shape will spontaneously return to that initial state upon heating. This behavior is reported to be related to a diffusionless shear transformation which takes place between similar but slightly different CsCl type structures.

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