Fracture in single crystal NiTi

Creuziger, Adam A.; Bartol, L; Gall, Ken; Crone, Wendy C.

doi:10.1016/j.jmps.2008.04.002

Cited by 48 publications

(15 citation statements)

References 32 publications

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“…At nominally constant temperatures, stress-induced phase transformation was reported by Robertson et al [6] and Gollerthan et al [7] near the crack tip in pseudoelastic polycrystalline NiTi under plane stress and plane strain conditions, respectively, and in single crystal NiTi by Creuziger et al [8]. The crack-tip stressinduced phase transformation is primarily responsible for the phenomenon of stable crack growth in SMAs under monotonically increasing load or displacement conditions, as shown in the experimental investigation of the fracture toughening behavior of an NiTi tube by Robertson and Ritchie [9].…”

Section: Introductionmentioning

confidence: 82%

On the Fracture Toughness of Pseudoelastic Shape Memory Alloys

Baxevanis

Landis

Lagoudas

2013

Journal of Applied Mechanics

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A finite element analysis of quasi-static, steady-state crack growth in pseudoelastic shape memory alloys is carried out for plane strain, mode I loading. The crack is assumed to propagate at a critical level of the crack-tip energy release rate. Results pertaining to the influence of forward and reverse phase transformation on the near-tip mechanical fields and fracture toughness are presented for a range of thermomechanical parameters and temperature. The fracture toughness is obtained as the ratio of the far-field applied energy release rate to the crack-tip energy release rate. A substantial fracture toughening is observed, in accordance with experimental observations, associated with the energy dissipated by the transformed material in the wake of the growing crack. Reverse phase transformation, being a dissipative process itself, is found to increase the levels of toughness enhancement. However, higher nominal temperatures tend to reduce the toughening of an SMA alloy-although the material's tendency to reverse transform in the wake of the advancing crack tip increases-due to the higher stress levels required for initiation of forward transformation.

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Section: Introductionmentioning

confidence: 82%

On the Fracture Toughness of Pseudoelastic Shape Memory Alloys

Baxevanis

Landis

Lagoudas

2013

Journal of Applied Mechanics

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“…Concentrated stress at the notch tip (or crack tip) will cause the martensite phase transformation which has been seen in both plane stress and plane strain conditions (Chen et al 2005;Daly et al 2007;Daymond et al 2007;Creuziger et al 2008). It has also been investigated using theoretical models (Yi and Gao 2000;Yi et al 2001;Wang et al 2005).…”

Section: Discussionmentioning

confidence: 99%

“…The martensite zone, grows with increasing applied stress (Daymond et al 2007) until it reaches a critical value at which the crack initiates. The martensite zone stays roughly constant in size during crack propagation (Creuziger et al 2008). The crack is known to grow more slowly in martensite compared with austenite (McKelvey and Ritchie 2001); this plus the creation of residual stresses acts as a toughening mechanism Falvo et al 2009).…”

Section: Discussionmentioning

confidence: 99%

Can the theory of critical distances predict the failure of shape memory alloys?

Kasiri

Kelly

Taylor

2011

Computer Methods in Biomechanics and Biomedical Engineering

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Components made from shape memory alloys (SMAs) such as nitinol often fail from stress concentrations and defects such as notches and cracks. It is shown here for the first time that these failures can be predicted using the theory of critical distances (TCDs), a method which has previously been used to study fracture and fatigue in other materials. The TCD uses the stress at a certain distance ahead of the notch to predict the failure of the material due to the stress concentration. The critical distance is believed to be a material property which is related to the microstructure of the material. The TCD is simply applied to a linear model of the material without the need to model the complication of its non-linear behaviour. The non-linear behaviour of the material at fracture is represented in the critical stress. The effect of notches and short cracks on the fracture of SMA NiTi was studied by analysing experimental data from the literature. Using a finite element model with elastic material behaviour, it is shown that the TCD can predict the effect of crack length and notch geometry on the critical stress and stress intensity for fracture, with prediction errors of less than 5%. The value of the critical distance obtained for this material was L = 90 μm; this may be related to its grain size. The effects of short cracks on stress intensity were studied. It was shown that the same value of the critical distance (L = 90 μm) could estimate the experimental data for both notches and short cracks.

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“…Creuziger et al observed the phase transformation in single crystal NiTi SMAs using optical techniques in situ. Their results showed that the general shape and structure of the transformation zone at the crack tip does not vary significantly throughout the crack propagation process (Creuziger et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Numerical simulation often is used to study the stress and phase transformation fields in front of the notches and cracks by finite element method (FEM) (Wang, 2006;Wang et al, 2005;Yi et al, 2001). Only recently, Daly et al (2007) and Creuziger et al (2008) experimentally investigated the phase transformation during fracture process, respectively. In Daly et al's work, shape and size of the saturation of martensite and phase transformation zone were assessed in thin-sheets of NiTi SMAs by strain field observation (Daly et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

The effect of notches on the fracture behavior in NiTi shape memory alloys

Wang

Yue

2009

International Journal of Solids and Structures

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a b s t r a c tTensile fracture experiments have been performed on double-notch plate form specimens with different notch types and sizes. Specimen without notch is also studied. The macromechanical responses as well as detail examination of the fracture surface have been carried out. The stress, plastic strain and phase transformation fields are analyzed by finite element (FE) simulations using a pseudoelastic constitutive model which considers the permanent plastic deformation. Experimental results show that different type of notches can influence not only the macro-mechanic pseudoelastic but also plastic behaviors of the specimens. Both notch type and notch size affect the mechanism of crack initiation. Notch size influences the specimen behavior in different way for different type of notches. Most of the experimental observations are interpreted properly by the FE results.

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Fracture in single crystal NiTi

Cited by 48 publications

References 32 publications

On the Fracture Toughness of Pseudoelastic Shape Memory Alloys

On the Fracture Toughness of Pseudoelastic Shape Memory Alloys

Can the theory of critical distances predict the failure of shape memory alloys?

The effect of notches on the fracture behavior in NiTi shape memory alloys

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