Modeling of Martensite Accommodation Effect on Mechanical Behavior of Shape Memory Alloys

1999 ◽  
Vol 121 (1) ◽  
pp. 102-104 ◽  
Author(s):  
M. E. Evard ◽  
A. E. Volkov
Keyword(s):  
Experimental Data ◽  
Plastic Deformation ◽  
Shape Memory Alloys ◽  
Mechanical Behavior ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Qualitative Agreement ◽  
Strain Accumulation ◽  
Good Qualitative Agreement

An approach has been presented to account for micro-plastic deformation and stress produced by accommodation of martensite. This has made it possible to describe such phenomena as incomplete recovery of strain, strain accumulation at thermocycling, and repeated two-way shape memory effect. Results of modeling are in good qualitative agreement with experimental data.

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.

Numerical simulation of the behavior of steel T-stubs connected by Fe-based shape memory alloy bolts

2018 ◽  
Vol 29 (16) ◽  
pp. 3284-3292 ◽  
Author(s):  
Cheikh Cissé ◽  
Wael Zaki ◽  
Tarak Ben Zineb
Keyword(s):  
Numerical Simulation ◽  
Plastic Deformation ◽  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Implicit Time ◽  
Integration Scheme ◽  
Iron Based

The article focuses on the numerical simulation of the thermomechanical behavior of steel T-stubs connected by iron-based shape memory alloys bolts. The three-dimensional macroscopic model used in this work was previously developed by the authors considering different thermomechanical properties between austenite and martensite, and coupling between phase transformation and plasticity. The model is implemented in a UMAT code using an implicit time-discrete integration scheme that follows a “multisurface plasticity”-like approach. The numerical results show that the shape memory effect can be used to preload the bolt if the initial length of its shank is less than the total thickness of the flanges. For an initial shank length of 21.38 mm and a total flange thickness of 21.4 mm, the shape memory effect produced average contact forces of 101 N between the bolt head and the flange, and 37 N between the two flanges. The resulting average contact pressures were 210 and 25 MPa, respectively. The average bolt force after preload was approximately 22.6 kN. Subsequent application of 2 mm normal displacements at the top and bottom faces of the upper and lower webs induced local plastic deformation around the flange holes and phase transformation in the bolt. The reversibility of martensitic transformation and the confinement of the plastic deformation in a limited zone around the holes allowed nearly complete shape recovery by heating. The obtained results highlight the advantage of using low-cost iron-based shape memory alloys as alternatives to steel bolts for connecting T-stubs.

On the impact of lattice parameter accuracy of atomistic simulations on the microstructure of Ni-Ti shape memory alloys

2021 ◽  
Author(s):  
Lorenzo La Rosa ◽  
Francesco Maresca
Keyword(s):  
Molecular Dynamics ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
Atomistic Simulations ◽  
Interatomic Potentials ◽  
The Impact

Abstract Ni-Ti is a key shape memory alloy (SMA) system for applications, being cheap and having good mechanical properties. Recently, atomistic simulations of Ni-Ti SMAs have been used with the purpose of revealing the nano-scale mechanisms that control superelasticity and the shape memory effect, which is crucial to guide alloying or processing strategies to improve materials performance. These atomistic simulations are based on molecular dynamics modelling that relies on (empirical) interatomic potentials. These simulations must reproduce accurately the mechanism of martensitic transformation and the microstructure that it originates, since this controls both superelasticity and the shape memory effect. As demonstrated by the energy minimization theory of martensitic transformations [Ball, James (1987) Archive for Rational Mechanics and Analysis, 100:13], the microstructure of martensite depends on the lattice parameters of the austenite and the martensite phases. Here, we compute the bounds of possible microstructural variations based on the experimental variations/uncertainties in the lattice parameter measurements. We show that both density functional theory and molecular dynamics lattice parameters are typically outside the experimental range, and that seemingly small deviations from this range induce large deviations from the experimental bounds of the microstructural predictions, with notable cases where unphysical microstructures are predicted to form. Therefore, our work points to a strategy for benchmarking and selecting interatomic potentials for atomistic modelling of shape memory alloys, which is crucial to modelling the development of martensitic microstructures and their impact on the shape memory effect.

Cold Bending a Ni-Ti Shape Memory Alloy Wire

2015 ◽  
Vol 661 ◽  
pp. 98-104 ◽  
Author(s):  
Kuang-Jau Fann ◽  
Pao Min Huang
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Room Temperature ◽  
Aging Treatment ◽  
Treatment Temperature ◽  
Bending Test ◽  
Solution Treatment Temperature

Because of being in possession of shape memory effect and superelasticity, Ni-Ti shape memory alloys have earned more intense gaze on the next generation applications. Conventionally, Ni-Ti shape memory alloys are manufactured by hot forming and constraint aging, which need a capital-intensive investment. To have a cost benefit getting rid of plenty of die sets, this study is aimed to form Ni-Ti shape memory alloys at room temperature and to age them at elevated temperature without any die sets. In this study, starting with solution treatments at various temperatures, which served as annealing process, Ni-rich Ni-Ti shape memory alloy wires were bent by V-shaped punches in different curvatures at room temperature. Subsequently, the wires were aged at different temperatures to have shape memory effect. As a result, springback was found after withdrawing the bending punch and further after the aging treatment as well. A higher solution treatment temperature or a smaller bending radius leads to a smaller springback, while a higher aging treatment temperature made a larger springback. This springback may be compensated by bending the wires in further larger curvatures to keep the shape accuracy as designed. To explore the shape memory effect, a reverse bending test was performed. It shows that all bent wires after aging had a shape recovery rate above 96.3% on average.

Effect of the Cutting Velocity and Heat Treatment on Turning Cutting Forces of an SMA Cu-Al-Be Alloys

2013 ◽  
Vol 758 ◽  
pp. 157-164
Author(s):  
Francisco Valdenor Pereira da Silva ◽  
José Paulo Vogel ◽  
Rodinei Medeiros Gomes ◽  
Tadeu Antonio de Azevedo Melo ◽  
Anna Carla Araujo ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Cutting Force ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Chip Formation ◽  
Cutting Forces ◽  
Cutting Velocity ◽  
Resultant Forces

This work studies the effect of heat treatment and cutting velocities on machining cutting forces in turning of a Cu-11.8%Al-0.55%Be shape memory alloys. The heat treatment was performed to obtain samples with austenite and martensite microstructures. Cutting force was investigated using a 3-component dynamometer in several revolutions and data were analyzed using statistic tools. It was found that the resultant forces were higher in quenched alloy due to the presence of Shape Memory Effect. Chip formation occurred in a shorter time in the sample without the Shape Memory Effect.

scholarly journals Microstructure Formation in Cast TiZrHfCoNiCu and CoNiCuAlGaIn High Entropy Shape Memory Alloys: A Comparison

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4227 ◽  
Author(s):  
Tetiana A. Kosorukova ◽  
Gregory Gerstein ◽  
Valerii V. Odnosum ◽  
Yuri N. Koval ◽  
Hans Jürgen Maier ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Microstructure Characterization ◽  
Microstructure Formation ◽  
High Entropy

The present study is dedicated to the microstructure characterization of the as-cast high entropy intermetallics that undergo a martensitic transformation, which is associated with the shape memory effect. It is shown that the TiZrHfCoNiCu system exhibits strong dendritic liquation, which leads to the formation of martensite crystals inside the dendrites. In contrast, in the CoNiCuAlGaIn system the dendritic liquation allows the martensite crystals to form only in interdendritic regions. This phenomenon together with the peculiarities of chemical inhomogeneities formed upon crystallization of this novel multicomponent shape memory alloys systems will be analyzed and discussed.

A three-dimensional phenomenological model for shape memory alloys including two-way shape memory effect and plasticity

2019 ◽  
Vol 136 ◽  
pp. 103085 ◽  
Author(s):  
Giulia Scalet ◽  
Fabrizio Niccoli ◽  
Cedric Garion ◽  
Paolo Chiggiato ◽  
Carmine Maletta ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Phenomenological Model ◽  
Three Dimensional

scholarly journals Mechanism of Improvement of Shape Memory Effect in NbC Containing Fe-Mn-Si-Based Shape Memory Alloys

2006 ◽  
Vol 70 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Kazuyuki Ogawa ◽  
Takahiro Sawaguchi ◽  
Takehiko Kikuchi ◽  
Setuo Kajiwara
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect

Evaluation of Shape Memory Effect and Wear Characteristics of Cu-Al-Be-Mn Quaternary Shape Memory Alloys

2017 ◽  
Vol 4 (9) ◽  
pp. 10099-10103
Author(s):  
A.G. Shivasiddaramaiah ◽  
U.S. Mallik ◽  
C. Krishnakanth ◽  
S. Prashantha
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Wear Characteristics
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