Phenomenological modeling of ferromagnetic shape memory alloys

Kiefer, Björn; Lagoudas, Dimitris C.

doi:10.1117/12.540081

Cited by 35 publications

(38 citation statements)

References 34 publications

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“…16,21 Motivated by the analysis of possible energy contributions that are physically relevant for the magnetic shape memory effect, the elastic strain energy, the Zeeman energy, which aims to align the internal magnetization with the externally applied magnetic field, and the magnetic anisotropy energy are included in the free energy expression. The latter can be viewed as the energy difference associated with magnetizing a magnetic material along preferred and non-preferred directions, or in other words as the energy associated with the rotation of the magnetization away from the magnetic easy axes.…”

Section: Governing Magnetomechanical Constitutive Equationsmentioning

confidence: 99%

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Modeling of the magnetic field-induced martensitic variant reorientation and the associated magnetic shape memory effect in MSMAs

Kiefer

Lagoudas

2005

SPIE Proceedings

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This work is concerned with the magnetic field-induced rearrangement of martensitic variants in magnetic shape memory alloys (MSMAs). In addition to the variant reorientation, the rotation of the magnetization and magnetic domain wall motion are considered as the microstructural mechanisms causing the macroscopically observable constitutive response. The considered free energy terms are the elastic strain energy, the Zeeman energy and the magnetocrystalline anisotropy energy. It is shown how thermodynamic constraints on the magnetization rotation lead to only partial reorientation of the martensitic variants under higher stresses. A straightforward methodology has been devised for the calibration of model parameters based on experimental data. The presented model predictions indicate an improvement of the predictability of the nonlinear strain hysteresis and in particular the magnetization hysteresis.Keywords: magnetic shape memory alloys, ferromagnetic shape memory effect, magnetic field induced strain, martensitic variant reorientation, magnetic hysteresis. MAGNETIC SHAPE MEMORY ALLOYS AND THEIR APPLICATIONSMagnetic shape memory alloys have been considered as alternative actuator materials to be used for applications not suitable for conventional shape memory alloys (SMAs). The high mobility of twin boundaries in the martensitic phase of MSMAs allows for high frequency magnetic actuation. Furthermore, because the deformation of the MSMA material is magnetic-field controlled, the actuation can in principle be initiated in a contact-free manner. A first generation of such actuators have been designed and built and are presently commercially available. 1-3Magnetic shape memory alloys (MSMAs) have intensely been researched since the first studies of their behavior were reported by Ullakko et al. (1996). 4 They found magnetic field-induced trains of nearly 0.2% in stress-free experiments on martensitic NiMnGa single crystals. Extensive experimental work on off-stoichiometric intermetallic compounds near the composition Ni 2 MnGa have yielded of up to 10% in single crystals. 5 Additional alloys have been investigated, such as FePd 6, 7 and CoNiAL, 8 among others. Under the influence of temperature and stress fields, MSMAs also exhibit conventional shape memory and pseudoelastic behavior.The magnetic field-induced rearrangement of martensitic variants and the associated actuation of large inelastic strains has been termed the magnetic shape memory effect (MSME). The process occurs because each of the variants possesses different preferred directions of magnetization, called magnetic easy axes. That way those variants that are more favorably oriented with respect to an externally applied magnetic field can be selected over other less favorably oriented ones, resulting in the observed macroscopic shape change. The field-induced deformation of the material is accompanied by a nonlinear change in its magnetization, a process which will be discussed in more detail in the following section. The phenomenological constitutive...

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Section: Governing Magnetomechanical Constitutive Equationsmentioning

confidence: 99%

“…(1) is constructed as a linear average of the contributions of each variant and corrected by the mixing term f ξ (ξ) and has a reference state value of G 0 . 16,21 The effective elastic compliance S, effective magnetization M and effective magnetic anisotropy energy G an are defined by…”

Section: Governing Magnetomechanical Constitutive Equationsmentioning

confidence: 99%

Modeling of the magnetic field-induced martensitic variant reorientation and the associated magnetic shape memory effect in MSMAs

Kiefer

Lagoudas

2005

SPIE Proceedings

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“…With a similar approach to Hirsinger and Lexcellent, Kiefer and Lagoudas developed a thermodynamic phenomenological model based on the internal variables. 18 By considering the magnetization limitation induced by variants' rotation, they further presented a thermodynamic model exhibiting first cycle effect and the internal magnetization. 19 Faidley et al presented a constitutive model for the reversible strain in Ni-Mn-Ga solenoid actuators.…”

Section: Introductionmentioning

confidence: 99%

Dynamics modeling of ferromagnetic shape memory alloys (FSMA) actuators

Tan

Elahinia

2006

SPIE Proceedings

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FSMAs like Ni2MnGa have attracted significant attention over the last few years. As actuators, these materials offer high energy density, large stroke, and high bandwidth. These properties make FSMAs potential candidates for developing Solid-Fluid Hybrid Actuations (SFHA), where the FSMA actuator provides the mechanical energy by the linear reversible displacements. In order to develop effective hydraulic pumps with the FSMA actuators, it is important to study the dynamic behavior in these materials. In this paper, a dynamic model is presented for an Ni 2 MnGa actuator. The Ni 2 MnGa actuator model consists of the dynamics of the actuator, kinematics of the actuator, constitutive model of the material, and reorientation kinetics. A constitutive model is proposed to take into account the elastic deformation as well as the reorientation. Simulations results are presented to demonstrate the dynamic behavior of the actuator.

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“…In this section a summary of the framework for the MSMA constitutive model previously proposed by the authors [18][19][20] is given. The model is concerned with the stress and magnetic field-induced rearrangement of martensitic variants and predicts the associated nonlinear, stress-dependent reorientation strain and magnetization hysteresis curves typically observed in experiments.…”

Section: Msma Constitutive Equationsmentioning

confidence: 99%

“…[13][14][15][16][17] Most of these formulations rely on the minimization of a free energy expression, which searches for equilibrium points in ideal processes. This paper and previous work by the authors, [18][19][20][21] however, is concerned with the influence of dissipative effects on the evolution of thermodynamic states and thus the loading history dependence of the constitutive response; an approach that has yielded powerful phenomenological models for conventional shape memory alloys.…”

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confidence: 99%

Modeling of the Stress- and Magnetic Field-Induced Variant Reorientation in MSMAs

Lagoudas¹

2006

47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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This paper is concerned with the modeling of the magnetic shape memory alloy (MSMA) constitutive response caused by the reorientation of martensitic variants. Following a summary of the constitutive model previously proposed by the authors, the nonlinear and hysteretic strain and magnetization response of MSMAs are investigated for two main loading cases, namely the magnetic field-induced reorientation of variants under constant uniaxial stress and the stress-induced reorientation under constant magnetic field. It is demonstrated in this work that the model captures the loading history dependence of the constitutive behavior through the evolution of internal state variables. Complex loading cases are also presented in which the sequence of the application of the stress and magnetic field strongly influences the predicted response. The relation of critical stresses and magnetic fields for the activation of the reorientation process are visualized in a variant reorientation diagram on which the considered loading paths are superimposed.

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Phenomenological modeling of ferromagnetic shape memory alloys

Cited by 35 publications

References 34 publications

Modeling of the magnetic field-induced martensitic variant reorientation and the associated magnetic shape memory effect in MSMAs

Modeling of the magnetic field-induced martensitic variant reorientation and the associated magnetic shape memory effect in MSMAs

Dynamics modeling of ferromagnetic shape memory alloys (FSMA) actuators

Modeling of the Stress- and Magnetic Field-Induced Variant Reorientation in MSMAs

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