Superelastic NiTi-alloys under torsional loading

Predki, W.; Klönne, M.

doi:10.1051/jp4:20031004

Cited by 4 publications

(5 citation statements)

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“…The mechanical hysteresis curves of the solid shaft samples and hollow shaft samples have been discussed in detail in [4,5,6]. By using these geometries it is possible to investigate the influence of the sample geometry on the fatigue behaviour.…”

Section: Resultsmentioning

confidence: 99%

“…The functional fatigue is characterised by three parameters as a function of the cycle number [4,5]. These parameters are the transformation stress s Ms , the apparent shear modulus of the austenite G A and the apparent stiffness of the austenit-martensit transformation G A-M .…”

Section: Resultsmentioning

confidence: 99%

“…A subsequent precipitation annealing at 350 C for a period of 60 minutes seems to be appropriate, because the samples treated at 500 C for a period of 15 minutes are showing a less favourable fatigue resistance [4]. Precipitation annealing at 350 C for a period of 60 minutes implicates an A F -temperature of 5.5…”

Section: Methodsmentioning

confidence: 99%

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Damping Factors and Fatigue Notch Factors of Pseudoelastic NiTi‐Shape Memory Alloys

Predki

Knopik

Klönne³

2004

Materialwissenschaft Werkst

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Pseudoelastic NiTi-shape memory alloys (SMAs) provide a high damping capacity and can be used in order to achieve a reduction of peak loads being caused by unexpected shock loading. These "pseudoelastic" properties are related to the formation of martensite M from austenite A, which has been induced by stress; they allow to refer to SMAs as functional materials. Furthermore, these functional materials can operate at high stresses and thus, have to withstand severe mechanical loadings like classical structural materials. In combination, these characteristics provide opportunities for technical applications, e.g., to reduce vibrations or to reduce peak loads caused by shock loading. An extensive knowledge of the functional and structural fatigue behaviour of the material is required to design SMA components. NiTi hollow shaft samples and solid shaft samples have been tested under cyclic torsional loading conditions in a load-controlled mode. By using these two geometries the influence of the sample geometry on the fatigue behaviour can be investigated. In addition, a test programme has been elaborated in order to investigate the behaviour of the material when subjected to bending. The experimental data have been evaluated describing the transformation behaviour induced by stress concerning transformation stress, apparent shear modulus of the austenite G A and apparent stiffness s Ms (describing the slope of the shear stress-strain-curve in the transformation range G A-M ). These parameters naturally depend on the cycle number, the load amplitude as well as the temperature. Engineering failures are often associated with the presence of notches. In this context, torsion tests on notched samples are planned to be carried out in order to assess the resulting data based on the results obtained from the notch free samples. This will allow to derive simple design rules based on fatigue notch factors, which are needed for engineering design.KEYWORDS

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Damping Factors and Fatigue Notch Factors of Pseudoelastic NiTi‐Shape Memory Alloys

Predki

Knopik

Klönne³

2004

Materialwissenschaft Werkst

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“…The superelasticity effect (SE) refers to the ability of a material to return to its original shape upon unloading after substantial deformation [5,[38][39][40][41]. At temperatures above the austenite finish, A f, temperature, the material is in its parent austenitic phase and the atomic structure is a simple cubic lattice.…”

Section: The Superelasticity Effectmentioning

confidence: 99%

Tensile and fatigue behavior of superelastic shape memory rods

Treadway

Abolmaali

et al. 2015

Materials & Design

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a b s t r a c tThe tensile and fatigue behavior of superelastic shape memory alloy (SMA) bars heat-treated at three different temperatures were examined. Low cycle fatigue tests at variable load rates were carried out to determine the effect of stress and frequency on residual strain and energy dissipation in a fatigue cycle. The mechanism of energy dissipation was studied by monitoring the temperature changes in the fatigued samples as a function of applied stress and frequency of testing. Results from the tensile tests revealed that the stress for the Austenite to Martensite transformation decreased from 408 MPa to 204 MPa with an increase in temperature of heat treatment from 300 to 450°C. The ultimate strength of the SMA increased from 952 MPa to 1115 MPa when the heat treatment temperature was increased from 300 to 450°C. Fatigue testing prior to conducting the tensile test decreased the ultimate strength of the SMA and also reduced the failure strain. The energy dissipation in fatigue tests was found to decrease as test frequency increased from 0.025 Hz to 0.25 Hz and the change in sample temperature during the test at the lower test frequency was found to be considerably higher than at the higher frequency.

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“…Structures of steel and NiTi can be subjected to comparable loads (cf. [5,14]), but in contrast to steel, NiTi shape memory alloys provide a high damping capacity. The latter is based on the dissipation of energy during a stress-induced phase transformation of the phases martensite and austenite, leading to a hysteresis observed in the stress strain space as depicted in Fig.…”

Section: Introductionmentioning

confidence: 96%

Damping Couplings with Elements of Pseudoelastic NiTi Shape Memory Alloys

et al. 2006

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A coupling device for damping within a drive train is presented. For conventional damping couplings, damping is often realized by the dissipation of energy due to material damping or friction. In opposite to this, the damping effect of the presented coupling is based on the dissipated energy during the stress induced phase transformation of pseudoelastic NiTi shape memory alloys. In this contribution the design principles, experimental results, and a numerical simulation using the material law for shape memory alloys developed by Raniecki B. Lexcellent C. and Tanaka K. (Arch Mech 44(3:261-284)) are presented.

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Superelastic NiTi-alloys under torsional loading

Cited by 4 publications

References 0 publications

Damping Factors and Fatigue Notch Factors of Pseudoelastic NiTi‐Shape Memory Alloys

Damping Factors and Fatigue Notch Factors of Pseudoelastic NiTi‐Shape Memory Alloys

Tensile and fatigue behavior of superelastic shape memory rods

Damping Couplings with Elements of Pseudoelastic NiTi Shape Memory Alloys

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