Thermodynamical constitutive model for the shape memory effect due to transformation and reorientation

1994 ◽  
Author(s):  
James G. Boyd ◽  
Dimitris C. Lagoudas
Keyword(s):  
Constitutive Model ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect

A Constitutive Model for Shape Memory Alloys Involving Transformation, Reorientation and Plasticity

2013 ◽  
Vol 535-536 ◽  
pp. 105-108
Author(s):  
Xiang He Peng ◽  
Min Mei Chen ◽  
Jun Wang
Keyword(s):  
Plastic Deformation ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Volume Fraction ◽  
Transformation Rule ◽  
Constitutive Behavior ◽  
Plastic Parts

A constitutive model is developed for shape memory alloys (SMAs) based on the concept that an SMA is a mixture composed of austenite and martensite. The deformation of the martensite is separated into elastic, thermal, reorientation and plastic parts, and that of the austenite is separated into elastic, thermal and plastic parts. The volume fraction of each phase is determined with the modified Tanaka’s transformation rule. The typical constitutive behavior of some SMAs, including pseudoelasticity, shape memory effect, plastic deformation as well as its effects, is analyzed.

Conventional Plasticity Constitutive Model for Shape Memory Alloys

2011 ◽  
Vol 216 ◽  
pp. 469-473
Author(s):  
Hai Tao Li ◽  
Xiang He Peng
Keyword(s):  
Shape Memory Alloy ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Numerical Algorithm ◽  
Individual Behavior ◽  
Two Phase ◽  
The Individual

A two-phase constitutive model for shape memory alloys (SMAs) is proposed based on the fact that SMAs is dynamically composed of austenite and martensite. The behavior of SMAs is regarded as the dynamic combination of the individual behavior of each phase. This model can describe the main characteristics of SMAs, such as pseudoelasticity and shape memory effect. The corresponding numerical algorithm was also developed to describe the main features of shape memory alloy Au-47.5at.%Cd.

A Multidimensional Constitutive Model for Shape Memory Alloys

2014 ◽  
Vol 584-586 ◽  
pp. 1141-1144
Author(s):  
Wei Wang ◽  
Ji Yuan Liu
Keyword(s):  
Free Energy ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Dissipation Energy ◽  
Thin Walled

A multidimensional constitutive model for shape memory alloys (SMA) is developed in the paper, which is based on the thermodynamics theories of free energy and dissipation energy. This model can well describe both the shape memory effect (SME) and super elasticity effect (SE) of the thin-walled SMA cylinder under an axial tensional force and torsion.

A Viscoelastic-Plastic Constitutive Model of Shape Memory Polymer

2019 ◽  
Vol 35 (5) ◽  
pp. 601-611 ◽  
Author(s):  
Xueyao Zheng ◽  
Bo Zhou ◽  
Shifeng Xue
Keyword(s):  
Constitutive Model ◽  
Stationary Phase ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Shape Memory Polymer ◽  
Memory Process ◽  
Mechanical Behaviors ◽  
Reversible Phase ◽  
Flow Element

ABSTRACTIt is of practical significance to develop a constitutive model which is able to predict the thermomechanical behaviors of the shape memory effect occurring in a shape memory polymer (SMP) accurately. The mechanism of shape memory effect of SMP is explained based on the assumption that SMP is composed by two phases, reversible phase and stationary phase. Especially the different flow elements are respectively added to the reversible phase and stationary phase in order to express the plastic behavior of SMP. There are two springs in series, one dashpot and one flow element in the reversible phase. There are two springs in parallel, one dashpot and one flow element in the stationary phase. A constitutive equation is developed to express the thermo-mechanical behaviors of shape memory effect in the SMP based on viscous-elastic mechanics and plastic theory. An internal variable, frozen ratio, is defined to follow the shape memory process in SMP, and the material properties are described as the functions of frozen ratio based on phase transition theorem. The developed constitutive model, which includes above constitutive equation and material parameter functions, is used to numerically simulate the thermo-mechanical behaviors of SMP under various load cycles. Results show that the developed constitutive model can not only predict the shape memory process of SMP accurately, but also express the rate-dependent behaviors of SMP effectively.

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.

A new type of intrinsic two-way shape-memory effect in hooks of NiTi-wires

2003 ◽  
Vol 112 ◽  
pp. 1177-1180 ◽  
Author(s):  
A. Schuster ◽  
H. F. Voggenreiter ◽  
D. C. Dunand ◽  
G. Eggeler
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
New Type ◽  
Niti Wires
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