Transformation Induced Cyclic Behavior and Fatigue Properties of Nickel Rich NiTi Shape Memory Alloy Actuators

Bertacchini, Olivier W.; Lagoudas, Dimitris C.; Calkins, Frederick T.; Mabe, James H.

doi:10.1002/9781118803592.ch28

Cited by 3 publications

(1 citation statement)

References 11 publications

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“…There exist a limited number of experimental investigations on actuation fatigue of SMAs. Effect of applied load level [27] and upper cycle temperature [15] together with the effect of corrosion environment [28,29] to the actuation fatigue properties and the microstructural damage evolution during actuation fatigue were examined and reported in the literature [20]. However, there are a couple of studies on the crack growth response of especially NiTiHf HTSMAs to the best of authors' knowledge.…”

Section: Introductionmentioning

confidence: 99%

Crack growth behavior during actuation cycling of hot extruded and annealed Ni₅₀Ti₃₀Hf₂₀ high temperature shape memory alloys

Ekiciler¹,

Kockar²

2022

Smart Mater. Struct.

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Actuator-type applications of High Temperature Shape Memory Alloys (HTSMAs) require better understanding of the crack growth behavior at high temperatures as there are few studies on how cracks propagate and cause fracture with phase transformation via cooling and heating under constant load. In this study, hot-extruded and subsequently annealed Ni50Ti30Hf20 (at.%) HTSMA dog-bone shaped tensile test samples with pre-notches were cooled and heated under uniaxially applied constant load magnitude till fracture. Therefore, the crack growth behavior and effect of annealing heat treatment on the crack growth rate of Ni50Ti30Hf20 (at.%) HTSMA during actuation fatigue were particularly determined. Additionally, fatigue tests were conducted twice on the pre-notched samples to investigate the repeatability of the data obtained from the experiments. It was shown that slower crack growth was observed in the pre-notched annealed samples than in the hot extruded samples because of the possible stress-relieving effect of annealing after the hot extrusion process. Several minor side crack formations and the propagation of these side cracks together with the crack growth behavior of the major crack were realized in the annealed samples. In contrast, the major crack growth rate was found to be higher than that of the growth rate of the minor side cracks. Additionally, the annealing process led to obtain consistent crack growth rate values and actuation behavior in the cooling-heating cycles.

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Section: Introductionmentioning

confidence: 99%

Crack growth behavior during actuation cycling of hot extruded and annealed Ni₅₀Ti₃₀Hf₂₀ high temperature shape memory alloys

Ekiciler¹,

Kockar²

2022

Smart Mater. Struct.

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A Study of Actuation Fatigue of Shape Memory Alloy

Agboola

Hartl

Lagoudas

2012

Volume 2: Mechanics and Behavior of Active Materials; Integrated System Design and Implementation; Bio-Inspired Materials and S

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The use of shape memory alloy (SMA) components as actuators is an attractive option for some aerospace, automotive, and oil and gas exploration applications, especially when installation volume is limited. Fatigue failures constitute a major structural reliability issue confronting industrial entities looking to employ this technology. Knowing and understanding the failure mechanism and resulting fatigue life of SMAs is therefore necessary and useful for design and certification prior to commercial use. An in-house developed experimental set-up based on Joule heating was used to complete a comprehensive set of fatigue tests on SMA actuators composed of a nickel-rich Nickel-Titanium (Ni-Ti) alloy subjected to cyclic thermomechanical loadings. A special forced convective cooling environment has been designed that utilizes compressed air and vortex tubes to maintain the test environment at a temperature well below the martensitic finish temperature. To thermally cycle the specimen, a time controlled scheme developed using LabVIEW was used. The system design allows full thermal cycling of large SMA specimens in approximately 80 seconds. Consequently, each test (comprised of thousands of cycles) takes weeks to be completed. Actuation fatigue life results of a complete test matrix for specimens undergoing full transformation at multiple stress levels are presented. Significant spread was observed in the number of cycles to failure for specimens under same isobaric loading across different choice of applied stress. Post-mortem microscopic observation of failed specimens suggested that failure is linked to cracks initiating within Ni3Ti precipitates. Observations reported further suggest that the failure of the specimen may not be due to plastic strain to failure.

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Mechanical Fatigue Characterization of NiTiHf SMAs for a Unified Descriptor to Actuation Fatigue

Padalia,

Lagoudas

2024

AIAA SCITECH 2024 Forum

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Transformation Induced Cyclic Behavior and Fatigue Properties of Nickel Rich NiTi Shape Memory Alloy Actuators

Cited by 3 publications

References 11 publications

Crack growth behavior during actuation cycling of hot extruded and annealed Ni₅₀Ti₃₀Hf₂₀ high temperature shape memory alloys

Crack growth behavior during actuation cycling of hot extruded and annealed Ni₅₀Ti₃₀Hf₂₀ high temperature shape memory alloys

A Study of Actuation Fatigue of Shape Memory Alloy

Mechanical Fatigue Characterization of NiTiHf SMAs for a Unified Descriptor to Actuation Fatigue

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Transformation Induced Cyclic Behavior and Fatigue Properties of Nickel Rich NiTi Shape Memory Alloy Actuators

Cited by 3 publications

References 11 publications

Crack growth behavior during actuation cycling of hot extruded and annealed Ni50Ti30Hf20 high temperature shape memory alloys

Crack growth behavior during actuation cycling of hot extruded and annealed Ni50Ti30Hf20 high temperature shape memory alloys

A Study of Actuation Fatigue of Shape Memory Alloy

Mechanical Fatigue Characterization of NiTiHf SMAs for a Unified Descriptor to Actuation Fatigue

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Product

Resources

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Crack growth behavior during actuation cycling of hot extruded and annealed Ni₅₀Ti₃₀Hf₂₀ high temperature shape memory alloys

Crack growth behavior during actuation cycling of hot extruded and annealed Ni₅₀Ti₃₀Hf₂₀ high temperature shape memory alloys