A phenomenological approach for the chemo-responsive shape memory effect in amorphous polymers

The article considers possibility of creating a safety element for a safe electrical outlet based on the shape memory effect. Numerical model of helical cylindrical spring of the shape memory alloy is developed. The phenomenological approach based on the phase transition diagram is used to describe material behavior. Shape memory effect is included using additional internal force factor i.e. the shape memory moment under torsion. An algorithm for constructing the relationship between the torque in cross section and the shape memory moment for isothermal loading is presented. The problem of simultaneous deformation of shape memory alloy spring and flat copper spring under heating is solved. The contact plate is replaced by an equivalent spring. Spring stiffness is obtained using a system of nonlinear differential equations describing the bending of a bar.

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A thermodynamic model for tunable multi-shape memory effect and cooperative relaxation in amorphous polymers

Smart Materials and Structures ◽

10.1088/1361-665x/aaf528 ◽

2019 ◽

Vol 28 (2) ◽

pp. 025031 ◽

Cited By ~ 7

Author(s):

Haibao Lu ◽

Xiaodong Wang ◽

Kai Yu ◽

Yong Qing Fu ◽

Jinsong Leng

Keyword(s):

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Thermodynamic Model ◽

Amorphous Polymers ◽

Cooperative Relaxation

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Modeling and FEM Simulation of Shape Memory Microactuators

Materials Science Forum ◽

10.4028/www.scientific.net/msf.583.229 ◽

2008 ◽

Vol 583 ◽

pp. 229-256 ◽

Cited By ~ 4

Author(s):

Berthold Krevet ◽

Manfred Kohl

Keyword(s):

Shape Memory ◽

Single Crystals ◽

Shape Memory Effect ◽

Memory Effect ◽

Performance Prediction ◽

Fem Simulation ◽

Phenomenological Approach ◽

Polycrystalline Materials ◽

Magnetic Shape Memory ◽

Insight Into

This article reports on two models for the shape memory effect and explains, how they are implemented in a finite element method program. The first model uses a phenomenological approach. For the example of a microgripper, the performance prediction of real actuators made of polycrystalline materials is demonstrated. In the second model, the martensite-austenite phase transition is treated as a thermodynamically activated process. Thermodynamic laws, like e.g. the minimization of the Gibbs free energy, are used for the formulation. To simplify the model, it is primarily intended to describe the behavior of single crystals. By comparing the simulated bending characteristic of a cantilever beam with experimental data, the applicability to polycrystalline material is tested. Due to the physics based formulation, this model gives more insight into the structural processes involved. This is very useful, e.g., for physical extensions needed for the simulation of the magnetic shape memory effect. It is shown, how the model can be extended to predict the behavior of actuators made of ferromagnetic Ni-Mn-Ga single crystals in a magnetic field.

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Tensile Failure of 55-Nitinol Wire

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113858 ◽

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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