Effects of thermo-mechanical cycling on the strain response of Ni–Ti–Cu shape memory alloy wire actuator

Saikrishna, C.N.; Ramaiah, K.V.; Bhaumik, SK

doi:10.1016/j.msea.2006.05.008

Cited by 39 publications

(20 citation statements)

References 20 publications

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“…zalicza się: temperatury krytyczne przemian, odkształcenie odzyskiwane (recovery strain) lub resztkowe odkształcenie fazy macierzystej [7,8,9,10,12]. W wielu przypadkach mówi się także często o tzw.…”

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“…ich degradacji [3]. Zdaniem autora, liczba dostępnych prac doświadczalnych na ten temat nie jest zbyt duża, zwłaszcza jeśli chodzi o SME realizowany pod wpływem obciążeń termomechanicznych o różnych profilach [6,8,12]. Dlatego też główną intencją niniejszej pracy jest próba oceny wpływu dwóch różnych profili obciążeń termomechanicznych na zmiany odkształceń odzyskiwanych i trwałych w Ni-Ti SMA.…”

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Wybrane Charakterystyki Funkcjonalne Stopu Ni-Ti Z pamięcią Kształtu W Warunkach Obciążeń Termomechanicznych

Kus¹

2007

Research Works of Air Force Institute of Technology

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Słowa kluczowe: stop Ni-Ti, obciążenia termomechaniczne, efekt pamięci kształtu (SME), wyżarzanie, temperatury przemian, analiza DSC i XRD. WprowadzenieOdwracalna przemiana martenzytyczna, a stąd unikatowe właściwości funkcjonalne stopów z pamięcią kształtu (SMA) sprawiają, że stopy te sprawdzają się w wielu inżynieryjnych i medycznych zastosowaniach [9,11], jak również w kosmicznych oraz wojskowych [5]. Przykładowo, Ni-Ti SMA są chętnie stosowane jako mikroczujniki i mikrosiłowniki, gdzie duże znaczenie ma działanie cykliczne. W takich elementach efekt pamięci kształtu (SME) może wystąpić pod wpływem różnych warunków termomechanicznych, a co za tym idzie, obserwowane jest ich różne zachowanie. Doniesienia literaturowe pokazują, że powtarzanie SME indukowanego na drodze obciążeń termicznych lub termomechanicznych powoduje

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Wybrane Charakterystyki Funkcjonalne Stopu Ni-Ti Z pamięcią Kształtu W Warunkach Obciążeń Termomechanicznych

Kus¹

2007

Research Works of Air Force Institute of Technology

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“…Due to the higher stresses required to form SIM at higher strain rates, more dislocations are introduced in the material. These dislocations may allow the generation of residual martensite, because of the stress fields generated in the material's microstructure, and/or contribute to the accumulation of irreversible deformation [25,26]. So it seems reasonable to assume that the cause of residual strain can be both, residual martensite and plastic deformation [21,25,27].…”

Section: * Technical Contribution To the 71º Congresso Anual Da Abm -mentioning

confidence: 99%

Influence of Strain Rate on the Functional Behavior of a Niti Alloy Under Pseudoelastic Training

Rodrigues¹,

Soares²,

Buono³

et al. 2017

Anais Do Congresso Anual Da ABM

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The present study deals with the effects of strain rate on the functional behavior of NiTi thin wires. The samples, in the austenitic condition at room temperature, were mechanically cycled 20 times by loading up to 6% strain followed by complete unloading, at 25°C. Four different quasi-static strain rates were assessed: 1x10 . The functional properties are described by means of critical stress to induce martensite, stress at maximum strain, energy dissipated per cycle and residual strain. The sensitivity of repeated cyclic deformation to strain rate is also analyzed in terms of phase stability. The results show that the fluctuation in the loading plateau, due to non-homogeneous transformation, increases with increasing strain rate. During cycling, it is observed that higher strain rates result in lower critical stress to induce martensite after the 5th cycle. However, the stress at maximum strain is higher at high strain rates, regardless the number of cycles. The accumulation of residual strain also increases with the strain rate due to the higher applied stress. During unloading, both the elastic deformation of stress-induced martensite and the reverse transformation seem to overlap at high strain rates. The dissipated energy behavior changes between the 1st and 20th cycle. No martensite is stabilized after training, but the intensity of the X-ray diffraction peaks of austenite increases with strain rate, as a result of stress relaxation.

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“…For example, Cu element is added to binary NiTi SMA so as to significantly lower the phase transformation hysteresis, which lays the foundation for the application of an actuator or micro-electro-mechanical system (MEMS) [7,8]. As a consequence, over the last few decades, many researchers have paid more attention to NiTiCu SMAs [9][10][11][12]. It is well known that plastic deformation substantially influences the microstructures and transformation behavior of NiTi-based SMAs [13,14].…”

Section: Introductionmentioning

confidence: 99%

Deformation Behavior and Microstructure Evolution of NiTiCu Shape Memory Alloy Subjected to Plastic Deformation at High Temperatures

Jiang

Sun

Zhang

et al. 2017

Metals

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Deformation behavior and microstructure evolution of NiTiCu shape memory alloy (SMA), which possesses martensite phase at room temperature, were investigated based on a uniaxial compression test at the temperatures of 700~1000 • C and at the strain rates of 0.0005~0.5 s −1 . The constitutive equation of NiTiCu SMA was established in order to describe the flow characteristic of NiTiCu SMA, which is dominated by dynamic recovery and dynamic recrystallization. Dislocations become the dominant substructures of martensite phase in NiTiCu SMA compressed at 700 • C. Martensite twins are dominant in NiTiCu SMA compressed at 800 and 900 • C. Martensite twins are not observed in NiTiCu SMA compressed at 1000 • C. The microstructures resulting from dynamic recovery or dynamic recrystallization significantly influences the substructures in the martensite phase of NiTiCu SMA at room temperature. Dislocation substructures formed during dynamic recovery, such as dislocation cells and subgrain boundaries, can suppress the formation of twins in the martensite laths of NiTiCu SMA. The size of dynamic recrystallized grains affects the formation of martensite twins. Martensite twins are not easily formed in the larger recrystallized grain, since the constraint of the grain boundaries plays a weak role. However, in the smaller recrystallized grain, martensite twins are induced to accommodate the transformation from austenite to martensite.

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Effects of thermo-mechanical cycling on the strain response of Ni–Ti–Cu shape memory alloy wire actuator

Cited by 39 publications

References 20 publications

Wybrane Charakterystyki Funkcjonalne Stopu Ni-Ti Z pamięcią Kształtu W Warunkach Obciążeń Termomechanicznych

Wybrane Charakterystyki Funkcjonalne Stopu Ni-Ti Z pamięcią Kształtu W Warunkach Obciążeń Termomechanicznych

Influence of Strain Rate on the Functional Behavior of a Niti Alloy Under Pseudoelastic Training

Deformation Behavior and Microstructure Evolution of NiTiCu Shape Memory Alloy Subjected to Plastic Deformation at High Temperatures

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