EXPERIMENTAL STUDY ON PERFORMANCES IN Cu-BASED SHAPE MEMORY ALLOY UNDER MULTI-AXIAL LOADING CONDITIONS

Tokuda, Masataka; Šittner, Petr; Takakura, M.; Men, Yongfeng

doi:10.2472/jsms.44.507appendix_260

Cited by 5 publications

(5 citation statements)

References 5 publications

(5 reference statements)

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“…Moreover, the well‐known tension–compression asymmetry has to be considered. Therefore, the description of the specific behaviour of SMA requires non‐isothermal models, able to take into account 3D proportional and non‐proportional loadings and the tension–compression asymmetry [2].…”

Section: Introductionmentioning

confidence: 99%

Multiaxial Shape Memory Effect and Superelasticity

Lavernhe-Taillard

Calloch

Chirani

et al. 2009

Strain

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WOSInternational audienceThe specific behaviour of shape memory alloys (SMA) is due to a martensitic transformation. This transformation consists mainly in a shear without volume change and is activated either by stress or temperature. The superelastic behaviour and the one-way shape memory effect are both due to the partition between austenite and martensite. The superelastic effect is obtained for fully austenitic SMA: loaded up to 5% strain, a sample recovers its initial shape after unloading with a hysteretic loop. The oneway shape memory effect is obtained when a martensitic SMA, plastically deformed, recovers its initial shape by simple heating. Superelasticity and one-way shape memory effect are useful for several three-dimensional applications. Despite all these phenomena are well known and modelled in 1D, the 3D behaviour, and especially the one-way shape memory effect, remains quite unexplored. Actually, the development of complex 3D applications requires time-consuming iterations and expensive prototypes. Predictive phenomenological models are consequently crucial objectives for the design and dimensioning of SMA structures. Therefore, a series of 2D proportional and non-proportional, isothermal and non-isothermal tests have been performed. This database will be used to build a phenomenological model within the framework of irreversible processes

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Section: Introductionmentioning

confidence: 99%

Multiaxial Shape Memory Effect and Superelasticity

Lavernhe-Taillard

Calloch

Chirani

et al. 2009

Strain

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“…Sun and Hwang [I] have constructed a macroscopic transformation condition of shape memory alloys from the microscopic response of the alloys, whereas Patoor et al [2] have shown, from the micromechanical investigation on the twin boundary movement in the variants, that the transformation surface in a single crystal is represented by a Prager type surface in the stress space, being different from a von Mises type ellipsoid familiar in plasticity. The transformation condition different from the von Mises criterion is supported by the extensive tension-torsion tests in a Cu-based alloy by Sittner and Tokuda [20,21].…”

Section: Introductionmentioning

confidence: 93%

Uniaxial Transformation Behavior in Tension and Compression in an Fe-Based Shape Memory Alloy : Transformation Lines and Thermomechanical Hystereses

1997

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Abstract. The uniaxial thermomechanical behavior of a polycrystalline Fe-9%Cr-5%Ni-14%Mn-6%Si (all wt.%) shape memory alloy is investigated for both tensile and compressive stress states. The martensite start stresses measured upon tension and compression loading of austenite depend linearly on temperature, thus forming straight lines in the stress-temperature regime. The lines belonging to tension and compression are not symmetric with respect to zero stress. The austenite start and finish temperatures measured upon heating under external stress, on samples which had previously been strained by inducing martensite, vary linearly with the stress level applied, thus forming the so-called austenite start and finish lines. The temperature difference (retransfornation range) between the austenite start and finish lines increases with increasing amount of previously induced straidmartensite, but the slopes of these lines remain the same. At the minimum amount of previously induced straidmartensite the start and finish lines coincide and are called initial austenite lines. The austenite start and finish lines obtained after previous tensile straining extend to the compression side without change of slope, while the austenite lines obtained after previous compression straining extend to the tensile side without change of slope. The determined tiansformation lines provide a good means to explain the thermomechanical response of the alloy, i.e., the stress-strain-temperature hysteresis loops.

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“…This yields X a = X Devtr where X = X(Icr, IIa,0, £) is the corresponding constitutive function. However, such an approach may not always lead to the satisfactory results as pointed out in [12]. Therefore, in the course of further development, the general form of the evolution law (5) will be used.…”

Section: The Phase Transformation Partmentioning

confidence: 99%

“…It is represented by a linear combination of deformation rates due to dislocation plasticity and transformation induced plasticity with the corresponding constants-weights which control the influence of each particular term: (10) The function f(a -a) in (9) represents a hypersurface in the space of stresses tr and microstresses or. In the most general case, for f(er -«) to represent a scalar invariant under the orthogonal isotropy group, we have the dependence where the invariants are defined by For example, one among possible choices for the function / belongs to the J 2 class of yield surfaces (11) By employing a consistency condition F = 0 and solving for A we obtain (12) ESOMAT 2000…”

Section: The Phase Transformation Partmentioning

confidence: 99%

Phenomenological modeling of shape memory effect using the concept of orientational back stress

Dobovšek

2001

J. Phys. IV France

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Abstract. A derivation of constitutive equations in a general three-dimensional setting is described, based on an additive decomposition of the rate of deformation tensor. The rate of deformation tensor is assumed to consist of an elastic part, a thermoelastic part, a plastic part, and a part due to phase transformation. The thermoelastic part due to thermoelastic coupling accounts for the influence of temperature near phase transformation, while the plastic part is taken in the form of classical flow theory of plasticity with combined isotropic and kinematic hardening, where the back stress represents a tensor of orientational micro-stresses. It is assumed that the part due to the phase transformation depends on the first and the second invariant of the tensor of crystallographic distortion, on the deviatoric part of the stress tensor, and on a special evolution parameter describing the rate of forming of a new phase. The derived constitutive equation is given in an explicit form with the corresponding tensor generators of the representation together with the irreducible integrity basis of the relevant tensor functions.

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EXPERIMENTAL STUDY ON PERFORMANCES IN Cu-BASED SHAPE MEMORY ALLOY UNDER MULTI-AXIAL LOADING CONDITIONS

Cited by 5 publications

References 5 publications

Multiaxial Shape Memory Effect and Superelasticity

Multiaxial Shape Memory Effect and Superelasticity

Uniaxial Transformation Behavior in Tension and Compression in an Fe-Based Shape Memory Alloy : Transformation Lines and Thermomechanical Hystereses

Phenomenological modeling of shape memory effect using the concept of orientational back stress

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