Rapid actuation and response of Ni–Mn–Ga to magnetic-field-induced stress

Smith, Aaron R.; Tellinen, J.; Ullakko, K.

doi:10.1016/j.actamat.2014.06.054

Cited by 52 publications

(26 citation statements)

References 19 publications

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“…An assumption was made that the average velocity is approximately equal to the instantaneous velocity under the driving force value of the pulse amplitude. The authors assumed that the effect of inertia is negligible.At the same time, some previous works indicate the possibility of rapid actuation of the sample when actual twin boundary pattern (consistent typically of multiple interfaces) was uncontrollable [5,10,11]. Actuation velocities of the order of few m/s were achieved (for example, 6 m/s in [5]).…”

mentioning

confidence: 98%

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Pulsed magnetic field-induced single twin boundary motion in Ni–Mn–Ga 5M martensite: A laser vibrometry characterization

et al. 2016

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mentioning

confidence: 98%

“…At the same time, some previous works indicate the possibility of rapid actuation of the sample when actual twin boundary pattern (consistent typically of multiple interfaces) was uncontrollable [5,10,11]. Actuation velocities of the order of few m/s were achieved (for example, 6 m/s in [5]).…”

mentioning

confidence: 98%

Pulsed magnetic field-induced single twin boundary motion in Ni–Mn–Ga 5M martensite: A laser vibrometry characterization

et al. 2016

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“…Magnetic-field-induced actuation of FSMAs results in strains as high as 12% for Ni-Mn-Ga alloys [4] with frequencies as high as 2 kHz [5]. Recent results show that twin boundaries accelerate to speeds of several meters per second in a few microseconds [6] which suggests actuation frequencies of hundreds of kHz.…”

Section: Introductionmentioning

confidence: 97%

Fatigue life and fracture mechanics of unconstrained Ni–Mn–Ga single crystals in a rotating magnetic field

Lawrence

Lindquist

Ullakko

et al. 2016

Materials Science and Engineering: A

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a b s t r a c tFracture resistance and long fatigue life are required to commercialize Ni-Mn-Ga ferromagnetic shape memory alloys. While Ni-Mn-Ga achieves high fatigue life at low strains, there is little data on the fatigue life of samples that are actuated near the theoretical strain limit. Furthermore, constraints imposed by clamping samples impact their magneto-mechanical and fatigue properties. Here, 10 M Ni-MnGa single crystals were exposed to a rotating magnetic field while holding them with rubber O-rings so they were minimally constrained. Prior to testing, sample surfaces were prepared to various levels of finish. Fatigue life varied with some samples reaching more than 800,000 cyclic loads before fracturing and some samples failing after only 4000 cyclic loads. Long fatigue life and fracture resistance are achieved when avoiding crystal defects and surface imperfections. Short fatigue life was caused by high surface roughness and stress concentration at defects and notches.

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“…Recently, higher temperature Ni-MnGa actuator materials were reported with 3 % strain recovery at 350 K [7]. Smith et al reported rapid actuation for these materials at room temperature with a twin boundary velocity of 82.5 ms -1 without load [4].…”

Section: Introductionmentioning

confidence: 99%

“…Ni-Mn-Ga elements have been proposed for use as fast and large-stroke actuators [1][2][3][4][5]. Ni-Mn-Ga single crystals used in spring actuators have actuation stresses from 0.1 to 2 MPa and elongation strains up to 6 % when driven by a magnetic field [3].…”

Section: Introductionmentioning

confidence: 99%

Working Ni–Mn–Ga Single Crystals in a Magnetic Field Against a Spring Load

Lindquist

Müllner

2015

Shap. Mem. Superelasticity

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This research characterizes ferromagnetic shape memory elements for use as mechanical actuators. A single crystal of Ni-Mn-Ga was pre-strained in compression from 0 to 6 % and then the shape was recovered with a magnetic field perpendicular to the loading direction while working against a pair of springs. The magnetic field was raised from 0 to 0.64 MA/m and then reduced to zero field. Eight pairs of springs with combined spring constants ranging from 14.3 to 269.4 N/mm were used. When the magnetic field was on, the sample expanded against the springs due to magnetic field-induced strain. When the magnetic field was turned off, the springs compressed the sample back to the initial size before the next cycle. During each cycle, force and displacement were measured and the specific work was computed. Specific work increased with the applied magnetic field and the pre-strain, with a maximum of 14 kJ/m 3 at 4.5 % pre-strain and 0.64 MA/m. This value is five times less than the values suggested in the literature which were inferred from stress-strain curves measured under various magnetic fields. The spring prescribes the load-displacement path of the magnetic shape memory element and controls the work output of the actuator.

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Rapid actuation and response of Ni–Mn–Ga to magnetic-field-induced stress

Cited by 52 publications

References 19 publications

Pulsed magnetic field-induced single twin boundary motion in Ni–Mn–Ga 5M martensite: A laser vibrometry characterization

Pulsed magnetic field-induced single twin boundary motion in Ni–Mn–Ga 5M martensite: A laser vibrometry characterization

Fatigue life and fracture mechanics of unconstrained Ni–Mn–Ga single crystals in a rotating magnetic field

Working Ni–Mn–Ga Single Crystals in a Magnetic Field Against a Spring Load

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