Actuator Classification and Selection—The Development of a Database

Zupan, Marc; Ashby, MF; Fleck, N.A.

doi:10.1002/adem.200290009

Cited by 137 publications

(85 citation statements)

References 4 publications

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“…In the present paper, we focus on NiTi actuator applications. Basic shape memory spring actuator principles are well known [6 -15] and SMA actuators show high power-to-weight ratios and can generate high stresses and strains [6,16]. When larger displacements are required, NiTi SM actuators are often used as helical coil springs, and the majority of actuator applications exploit the oneway shape memory effect.…”

Section: Introductionmentioning

confidence: 99%

Processing and property assessment of NiTi and NiTiCu shape memory actuator springs

Großmann

Frenzel²,

Sampath

et al. 2008

Materialwissenschaft Werkst

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Among the multifarious engineering applications of NiTi shape memory alloys (SMAs), their use in actuator applications stands out. In actuator applications, where the one-way effect (1WE) of NiTi SMAs is exploited, SM components are often applied as helical coil springs. Ingots are generally used as starting materials for the production of springs. But before SM actuator springs can be manufactured, the processing of appropriate wires from NiTi ingots poses a challenge because cold and hot working of NiTi SMAs strongly affect microstructure, and it is well known that the functional properties of NiTi SMAs are strongly dependent on their microstructure. The objective of the present paper is therefore to produce binary Ni 50 Ti 50 and ternary Ni 40 Ti 50 Cu 10 SMA actuator springs, starting from ingots produced by vacuum induction melting. From these ingots springs are produced using swaging, rolling, wire drawing and a shape-constraining procedure in combination with appropriate heat treatments. The evolution of microstructure during processing is characterized and the mechanical properties of the wires prior to spring-making are documented. The mechanical and functional characteristics of the wires are investigated in the stress-strain-temperature space. Finally, functional fatigue testing of actuator springs is briefly described and preliminary results for NiTi and NiTiCu actuator springs are reported.

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Section: Introductionmentioning

confidence: 99%

Processing and property assessment of NiTi and NiTiCu shape memory actuator springs

Großmann

Frenzel²,

Sampath

et al. 2008

Materialwissenschaft Werkst

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“…The ability to transduce heat and strain renders shape memory materials useful in a wide variety of actuation, energy damping, and energy harvesting applications (3)(4)(5)(6)(7). To be of practical use, the material must be able to accommodate the extreme deviatoric strains associated with the phase transformation without cracking or otherwise sustaining damage.…”

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confidence: 99%

Shape Memory and Superelastic Ceramics at Small Scales

Lai

Gan

et al. 2013

Science

267

197

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Shape memory materials are a class of smart materials able to convert heat into mechanical strain (or strain into heat), by virtue of a martensitic phase transformation. Some brittle materials such as intermetallics and ceramics exhibit a martensitic transformation, but fail by cracking at low strains and after only several applied strain cycles. Here we show that such failure can be suppressed in normally brittle martensitic ceramics by providing a fine-scale structure with few crystal grains. Such oligocrystalline structures reduce internal mismatch stresses during the martensitic transformation, and lead to robust shape memory ceramics capable of many superelastic cycles to large strains; here we describe samples cycled up to 50 times, and samples which can show strains over 7%. Shape memory ceramics with these properties represent a new class of actuators or smart materials with a unique set of properties that include high energy output, high energy damping, and high temperature usage.One Sentence Summary: Fine-scale shape memory ceramics capable of many actuation cycles to strains up to 7%.Main Text: Shape memory materials are solid-state transducers, able to convert heat to strain and vice versa. They exhibit two unique properties: 1) the shape memory effect, which is the ability to transform to a "remembered" pre-defined shape upon the application of heat and 2) superelasticity, which is the ability to deform to large strains recoverably, while dissipating energy as heat. The underlying mechanism in crystalline shape memory materials is a thermoelastic martensitic transformation between two crystallographic phases that can be induced thermally (shape memory effect) or with the application of stress (superelasticity) (1, 2).The ability to transduce heat and strain renders shape memory materials useful in a wide variety of actuation, energy damping, and energy harvesting applications (3-7). To be of practical use, the material must be able to accommodate the extreme deviatoric strains associated with the

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“…The proceedings of the SPIE annual Smart Structures and Materials Symposium feature sessions on Electro-active Polymers, Ferroelectrics and Ferroelectric Shape Memory Alloys. Papers by Ashby and colleagues describe methods used to create a database of actuator properties [5].…”

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confidence: 99%