Electro-thermomechanical behaviour of a Ti-45.0Ni-5.0Cu (at.%) alloy during shape memory cycling

Araújo, Carlos José de; Morin, Michel; Guénin, G.

doi:10.1016/s0921-5093(99)00360-3

Cited by 23 publications

(18 citation statements)

References 7 publications

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“…However, R-phase transformation is not fully beneficial for those applications where a position control is required (e.g. actuators) [4][5]14,[16][17][18][19][20] . Based on aforementioned backgrounds, the objectives of this paper are: to determine the influence of the cooper wheel velocity, heat treatment and chemical composition over the thermal and electrical behavior of the ribbons, and to estimate which conditions are the more interesting for possible applications in the field of micro-actuators or micro-robotics, taking into account only the SATWME of the ribbons electrically heated, which could be a normal situation in the field of actuators.…”

Section: Fementioning

confidence: 99%

Effect of Spun Velocities and Composition on the R‒phase and Thermomechanical Behavior in Ti‒Ni Ribbons Electrically Heated

et al. 2016

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This work deals with structural, electrical and mechanical characterization of Ti-50.13Ni and Ti-49.62Ni (at.%) shape memory alloys (SMAs) fabricated at different circumferential wheel velocities. The effect of wheel velocity, chemical composition and heat treatments are investigated. The characterization of crystallographic phases of the Ti-Ni ribbons was carried out using X-ray diffraction. Electrical resistance variations as function of temperature (∆R/R %) were analyzed using a non-commercial technique, which consists in a thermal-adjustable bath apparatus revealing the temperatures of B2→R→B19´ two stage transformation, whereby the presence of R-phase can be definitively confirmed. The Stress-Assisted Two-Way Memory Effect was measured by an own designed apparatus with an Linear Variable Differential Transformer captor and a current controlled heating, and results indicate that the as-spun condition, promotes the Stress-Assisted Two-Way Memory Effect. On the other hand, increments in Ni content tend to decrease transformation temperatures and high wheel velocities help to the R-phase formation.

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Section: Fementioning

confidence: 99%

Effect of Spun Velocities and Composition on the R‒phase and Thermomechanical Behavior in Ti‒Ni Ribbons Electrically Heated

et al. 2016

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“…Recently, Pozzi and Airoldi [6] has pointed out that resistivity of the alloy changes during reorientation of the martensite variants. De Araujo et al [7] also observed electrical resistance variations of nearly 15% with increasing stress levels and attributed it to the rearrangement of martensite variants. If the magnitude of transformation-induced and martensite rearrangement-induced resistance changes are established this information can be used for a clear interpretation of the deformation behavior of shape memory alloys under a variety of thermo-mechanical loading conditions.…”

Section: Introductionmentioning

confidence: 96%

Transformation and detwinning induced electrical resistance variations in NiTiCu

Kotil

Şehitoğlu

Maier

et al. 2003

Materials Science and Engineering: A

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Utilizing electrical resistance measurements in combination with strain observations on single crystals, it was possible to distinguish the austenite to martensite transformation from the detwinning of the martensite behavior during deformation of NiTiCu shape memory alloys. It was found that the electrical resistance change associated with the detwinning of the martensite variants was as high as 45% in deformation experiments below the martensite start temperatures. When the conditions led to partial detwinning of the martensite variants (tension at 20 8C) the corresponding electrical resistance changes were 20%. In the tension case at 20 8C, the electrical resistance measurements convincingly identified the end of the stress plateau as the conclusion of the transformation and the onset of detwinning. The detwinning is also activated following austenite to martensite transformation under thermal cycling experiments under a constant stress (shape memory under constant stress). In this case, the electrical resistance change associated with detwinning also reached high levels (45%) and coincided with the change in slope of the strain Á/temperature curves. #

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“…Mechanical fatigue properties of SMAs have been primarily studied based on the pseudoelastic response of SMAs with some key results presented by Tobushi et al [5] and Miyazaki et al [6]. However, thermally induced transformation fatigue is a more recent subject, where the applied level of stress has a major influence on the development of plastic strains and therefore on a low cycle fatigue performance of SMA actuators (Bigeon and Morin [7], De Araujo et al [8], Lagoudas et al [9], Cuellar et al [10]). …”

Section: Introductionmentioning

confidence: 99%

Surface Crack Development In Transformation Induced Fatigue Of Sma Actuators

Lagoudas

Bertacchini

Patoor

Residual Stress and Its Effects on Fatigue and Fracture

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This paper is based on the study of a post mortem analysis of shape memory alloy (SMA) actuators undergoing thermally induced martensitic phase transformation fatigue under various stress levels. Fatigue life results were obtained for both complete and partial phase transformation cycles applied to the SMA actuators. The thermal cyclic loading was induced by forced fluid convection cooling in order to increase the cycling frequency to approximately 1Hz, resulting to corrosion assisted fatigue. The combination of corrosion and reversible phase transformation under stress led to the formation of circular cracks on the surface of the cylindrical SMA wire actuators, which eventually saturated in a periodical distribution. In order to understand the stress field contributions to the microcracking in the presence of eigenstrains, a shear lag model was developed. The model accounts for eigenstrains introduced by corrosion, plastic strain accumulation with the number of cycles and the cyclic phase transformation strain. Comparison of the model predictions with crack spacing reached at fatigue failure is carried out and the reduction of fatigue life of SMA actuators under a corrosive environment is discussed.

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Electro-thermomechanical behaviour of a Ti-45.0Ni-5.0Cu (at.%) alloy during shape memory cycling

Cited by 23 publications

References 7 publications

Effect of Spun Velocities and Composition on the R‒phase and Thermomechanical Behavior in Ti‒Ni Ribbons Electrically Heated

Effect of Spun Velocities and Composition on the R‒phase and Thermomechanical Behavior in Ti‒Ni Ribbons Electrically Heated

Transformation and detwinning induced electrical resistance variations in NiTiCu

Surface Crack Development In Transformation Induced Fatigue Of Sma Actuators

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