Magnetic field-induced martensitic variant reorientation in magnetic shape memory alloys

Kiefer, Björn; Lagoudas, Dimitris C.

doi:10.1080/14786430500363858

Cited by 143 publications

(151 citation statements)

References 60 publications

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“…Several significant extensions have been made [39][40][41] to address this and other issues 1. The assumed constraint that the magnetization is fixed to the respective magnetic easy axes of the martensitic variants has been alleviated, with the introduction of additional internal state variables for the magnetization rotation.…”

Section: Modeling Workmentioning

confidence: 99%

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Magnetic Shape Memory Alloys with High Actuation Forces

Караман¹,

Lagoudas²

2006

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Public Reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comment regarding this burden estimates or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and 43794.4-MS SUPPLEMENTARY NOTESThe views, opinions and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of the Army position, policy or decision, unless so designated by other documentation. The specific aims of the project are: 1) Understand governing mechanisms and important physical, mechanical and magnetic parameters responsible for magnetic shape memory phenomena in MSMA alloys in single crystalline form, 2) to develop new nickel, iron or cobalt base ferromagnetic alloy compositions to increase attainable actuation stress levels and to reveal new mageto-thermomechanical mechanisms, 3) to conduct experiments to evaluate whether these compositions will result in good magnetic shape memory response and high actuation force, and 4) to develop a thermodynamically sound model that will predict the coupled effects of mechanical load, magnetic field and temperature on magnetic shape memory behavior. The main accomplishments in the project are: 1) the maximum actuation stress level was increased from 2 MPa to 5 MPa for the magnetic field induced martensite reorientation mechanism for the same amount of actuation strain (6%). 2) For the first time, the team observed cyclic magnetic field induced martensite to austenite transformation. This was confirmed using in-situ magnetic field experiments in an XRD at Argonne National Lab. 3) By utilizing this new actuation mechanism, the team was able to increase the cyclic actuation stress to 24 MPa with about 0.5% actuation strain. These numbers can be increased further. The mechanism has also resulted in field-induced one-way shape memory effect. In this effect, the actuation stress varied between 60 to 100 MPa with actuation strain levels are up to 3%. 4) The team found out the conditions to obtain magnetoelasticity utilizing the above two microstructural mechanisms under cycling loading (cyclic stress under magnetic field or magnetic field under constant stress). 5) development of a thermodynamically consistent phenomenological model which captures the ferromagnetic shape memory effect, i.e. the large macroscopically observable shape change of magnetic shape memory materials under the application of external magnetic fields and magnetizatiob evolution. The significance of these accomplishments is that the selected compositions after specific thermomechanical treatments are revealed promising new actuation mechanism an...

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Section: Modeling Workmentioning

confidence: 99%

“…This model provided good predictability of the magnetic field-induced strain hysteresis curves [33,[39][40], but failed to give accurate predictions of the magnetization hysteresis. Several significant extensions have been made [39][40][41] to address this and other issues 1.…”

Section: Modeling Workmentioning

confidence: 99%

Magnetic Shape Memory Alloys with High Actuation Forces

Караман¹,

Lagoudas²

2006

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“…Similarly, from the evolution equation for the internal magnetization (2.13), we can write for any generic γ β v , 6) and for the hardening function…”

Section: Materials Symmetry and Constitutive Equations For Magnetic Shmentioning

confidence: 99%

“…The second approach to study the material behaviour is thermodynamics-based phenomenological modelling. The hysteretic behaviour of such a material system is taken into account through the evolution of internal state variables that account for the presence of the different martensitic variants within the magnetic alloy [5,6]. More detailed description of internal state variable-based approach for conventional shape memory alloys can also be found in references [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Constitutive modelling of magnetic shape memory alloys with discrete and continuous symmetries

Haldar

Lagoudas

2014

Proc. R. Soc. A.

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A free energy-based constitutive formulation is considered for magnetic shape memory alloys. Internal state variables are introduced whose evolution describes the transition from reference state to the deformed and transformed one. We impose material symmetry restrictions on the Gibbs free energy and on the evolution equations of the internal state variables. Discrete symmetry is considered for single crystals, whereas continuous symmetry is considered for polycrystalline materials.

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“…MSMAs as materials that undergo large and completely reversible non-linear deformation influenced by an external magnetic field have been known for a relatively short time. However, since that time many theoretical models have been developed and used for modelling their quasi-static behaviour, magnetic-field-induced strains, all related with the MSME [5,6]. The MSME can be considered as a significant and completely reversible non-linear deformation in the martensitic phase driven by an external magnetic field.…”

Section: Magnetic Shape Memory Effectmentioning

confidence: 99%