Principle Design of Actuators Driven by Magnetic Shape Memory Alloys

Schlüter, Kathrin; Holz, Benedikt; Raatz, Annika

doi:10.1002/adem.201200078

Cited by 45 publications

(42 citation statements)

References 5 publications

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“…The MIR can be utilized in applications requiring fast actuation with large strain [5], while the inverse MIR (modification of magnetic field by the ferromagnetic twin microstructure rearrangement) can be used for sensing-type applications or vibrational energy harvesting. It turns out that for good application performance the twinning stress must typically be as low as possible, of the order of 0.1 MPa [10,11], or around 1 MPa in certain cases [12]. That is up to three orders lower than the twinning stress of ordinary shape memory materials [13].…”

Section: Introductionmentioning

confidence: 99%

The relation between lattice parameters and very low twinning stress in Ni₅₀Mn_25+xGa_25−xmagnetic shape memory alloys

Straka

Drahokoupil

Pacherová

et al. 2015

Smart Mater. Struct.

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In search for the origins of the extraordinary low twinning stress of Ni-Mn-Ga magnetic shape memory alloys we studied the thermally induced changes of structure in Ni 50 Mn 25+x Ga 25−x (x=2.7-3.9) single crystal samples and compared them with twinning stress dependences. The alloys exhibited transformation to five-layered (10M) martensite structure between 297 to 328 K. All samples exhibited magnetic shape memory effect. Just below the transformation temperature the samples had very low twinning stress of about 0.1-0.3 MPa, which increased with decreasing temperature. The structural changes were monitored using X-ray diffraction in the temperature range 173-343 K. The 10M structure was approximated by monoclinic lattice with the unit cell derived from the cubic unit cell of the parent L2 1 phase. With decreasing temperature, the lattice parameters a and γ increased, c decreased, while b was nearly constant. For x ≤ 3.5, sudden sharp changes in a and b parameters additionally occurred, resulting in a = b in some regions of the phase diagram, which might be related to the refinement of twin structure of 10M martensite on nanoscale. The temperature dependences of lattice parameter γ (and c or c/a) correlate well with the temperature dependences of twinning stress in agreement with the prediction by a microstructural model of twin boundary motion. On the contrary, there is no correlation between (a − b) and twinning stress. This indicates no significant role of a/b twins or laminate in twin boundary motion mechanism and low twinning stress.

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Section: Introductionmentioning

confidence: 99%

The relation between lattice parameters and very low twinning stress in Ni₅₀Mn_25+xGa_25−xmagnetic shape memory alloys

Straka

Drahokoupil

Pacherová

et al. 2015

Smart Mater. Struct.

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“…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]. These researchers also discussed various actuator designs including push-push actuators, push-pull actuators, and spring-loaded actuators.…”

Section: Introductionmentioning

confidence: 98%

“…For microactuators with a square cross section of (200 lm 9 200 lm) and a length of 4 mm work output increases from 10 to 140 kJ/m 3 as the compressive stress varies from less than 1 to 10 MPa [9,10]. Couch and Schlüter et al [1,3] measured the stress or strain of the element while it works against the spring. Schlüter et al reported actuation strains of 3.5 % (0.7 mm expansion and contraction for a 20 mm sample length) for a spring-loaded configuration when a 0-5 A sinusoidal current is applied to an electromagnet.…”

Section: Introductionmentioning

confidence: 99%

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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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“…Terfenol-D). Ordinary SMA are activated thermally and in order to distinguish both groups of materials with shape memory, it is proposed to use names and abbreviations: TSMA for thermally activated alloys and MSMA for magnetically activated ones [4,5,12]. When external magnetic field is applied to the MSMA material sample, it elongates or contracts, accordingly to the direction of the magnetic field vector and initial state of the sample.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of the Improved Magnetic Shape Memory Alloy Actuator Test Stand

Nowak

Minorowicz

Stefański

et al. 2015

Advances in Intelligent Systems and Computing

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Abstract. The article describes improved magnetic shape memory alloy actuator (MSMA actuator) test stand and the previously made stand. There are pointed weak sides of the first stand and the improvements in the new one. Several quasi-static measurements were performed and results were compared between both measurement stands. The MSMA actuator characterises with significant hysteresis loop, but improved test stand allowed to reduce its width. The increased rigidity of the stand excluded influence of stand deformations on the results. The described stand resulted with similar but improved measurements of the MSMA actuator characteristics, which also proved the correctness of the previous results.

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Principle Design of Actuators Driven by Magnetic Shape Memory Alloys

Cited by 45 publications

References 5 publications

The relation between lattice parameters and very low twinning stress in Ni₅₀Mn_25+xGa_25−xmagnetic shape memory alloys

The relation between lattice parameters and very low twinning stress in Ni₅₀Mn_25+xGa_25−xmagnetic shape memory alloys

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

Characteristics of the Improved Magnetic Shape Memory Alloy Actuator Test Stand

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Principle Design of Actuators Driven by Magnetic Shape Memory Alloys

Cited by 45 publications

References 5 publications

The relation between lattice parameters and very low twinning stress in Ni50Mn25+xGa25−xmagnetic shape memory alloys

The relation between lattice parameters and very low twinning stress in Ni50Mn25+xGa25−xmagnetic shape memory alloys

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

Characteristics of the Improved Magnetic Shape Memory Alloy Actuator Test Stand

Contact Info

Product

Resources

About

The relation between lattice parameters and very low twinning stress in Ni₅₀Mn_25+xGa_25−xmagnetic shape memory alloys

The relation between lattice parameters and very low twinning stress in Ni₅₀Mn_25+xGa_25−xmagnetic shape memory alloys