Phase transformation volume amplitude as a low-cycle fatigue indicator in nickel–titanium shape memory alloys

Paranjape, Harshad M.; Ng, Bill; Ong, Ich; Vien, Lot; Huntley, Christopher

doi:10.1016/j.scriptamat.2019.12.014

Cited by 8 publications

(5 citation statements)

References 16 publications

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“…Full-field measurements will also guide the development and validation of models capable of reproducing inhomogeneous deformations [72,75,76] like the strain localization bands observed here ( Figure 11). Measurements of medical devices undergoing emulated physiological loading may also be useful for detecting cyclic crystallographic phase transformation, which has recently been demonstrated to be an indicator for low-cycle fatigue failure [45,46]. While more advanced methods such as high-energy X-ray diffraction can provide a more direct measure of the phase transformation (e.g., [77]) in bulk samples such as medical devices, the 2D-DIC method described here provides access to similar information with a substantially simpler experimental setup.…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, DIC has been used previously for validating finite element (FE) biomechanics models of femoral [25], hemipelvic [26], craniofacial [27], and dental [28] implants as well as replica [29] and cadaveric [30,31] femurs. Digital image correlation has also been used to investigate the mechanics of polycrystalline nickel titanium (nitinol) starting in the mid 2000s [32,33], with interest rapidly increasing since that time (e.g., [34][35][36][37][38][39][40][41][42][43][44][45][46]; Figure 1). However, direct strain measurement on finished nitinol cardiovascular devices using either strain gauges or full-field DIC has been impractical to date due to limitations of scale, with typical strut cross-sectional dimensions measuring only a few hundred microns as illustrated in Figure 2.…”

Section: Introductionmentioning

confidence: 99%

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Full-field microscale strain measurements of a nitinol medical device using digital image correlation

Aycock

Weaver

Paranjape³

et al. 2021

Journal of the Mechanical Behavior of Biomedical Materials

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Computational modeling and simulation are commonly used during the development of cardiovascular implants to predict peak strains and strain amplitudes and to estimate the associated durability and fatigue life of these devices. However, simulation validation has historically relied on comparison with surrogate quantities like force and displacement due to barriers to direct strain measurement-most notably, the small spatial scale of these devices. We demonstrate the use of microscale two-dimensional digital image correlation (2D-DIC) to directly characterize full-field surface strains on a nitinol device coupon under emulated physiological loading. Experiments are performed using a digital optical microscope and a custom, temperature-controlled load frame. Following applicable recommendations from the International DIC Society, hardware and environmental heating studies, noise floor analyses, and inand out-of-plane rigid body translation studies are first performed to characterize the microscale DIC setup. Uniaxial tension experiments are also performed using a polymeric test specimen up to nominal stains of 5%. Sub-millimeter fields of view and sub-micron displacement accuracies (9 nm mean error) are achieved, and systematic (mean) and random (standard deviation) errors in strain are each estimated to be approximately 1,000 µ. The system is then demonstrated by acquiring measurements at the root of a 300 µm-wide nitinol device strut undergoing fixed-free cantilever bending motion. Lüderslike transformation bands are observed originating from the tensile side of the strut that spread toward the neutral axis at an angle of approximately 55°. Optical microscale 2D-DIC setups like that demonstrated herein will be useful in future studies for characterizing cardiovascular implant micromechanics, validating computational models, and guiding the development of next-generation material models for simulating superelastic nitinol.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Full-field microscale strain measurements of a nitinol medical device using digital image correlation

Aycock

Weaver

Paranjape³

et al. 2021

Journal of the Mechanical Behavior of Biomedical Materials

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“…Ring [241] Notched plate [238] [ 67, 107, 127, 145, 153, 173-175, 180, 190, 199, 205, 208, 209, 217, 222, 230, 234, 237, 238, 246-248, 251, 256, 262, 267, 274, 279, 282, 284, 292, 304, 305, 322] Meuwissen specimen [198,210,211] Diamond shape [287,303] Porous SMA [318,320] 3D printed [232,286,302,308]…”

Section: Conclusion and Suggestions For Future Workmentioning

confidence: 99%

Applying Full-Field Measurement Techniques for the Thermomechanical Characterization of Shape Memory Alloys: A Review and Classification

Delpueyo

Jury

Balandraud

et al. 2021

Shap. Mem. Superelasticity

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Full-field measurement techniques are now mature. As such, they have profoundly impacted the experimental mechanics community in recent years. The way that shape memory alloys (SMAs) are now tested is not spare from this deep-rooted trend, as reflected by the increasing number of papers published in the SMA literature. In this context, the aim of this contribution is to give an overview of the use of full-field measuring techniques for SMA characterization purposes. We recall first the basic principle of one volume and four surface techniques employed in this community. Several typical papers where such techniques are employed are then presented, by highlighting in each case the extent to which the thermomechanical response of SMAs could be better understood and modeled thanks to these techniques. A classification by several criteria of about 300 references is finally offered and discussed. The main criteria are the type of SMA, the type of technique employed to perform the measurements, and the type of test.

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“…Thus, we have demonstrated that the uncertainty information furnished by the BI-based calibration approach can be propagated to fatigue simulations of NiTi and it can result in appreciable uncertainty in the fatigue indicator parameters. Similar to strains, if other fatigue indicator parameters for NiTi such as the phase transformation volume amplitude [30] are extracted from the simulations, then those values will be affected by the material parameter uncertainty as well.…”

Section: Propagation Of Materials Parameter Uncertainty To Simulationsmentioning

confidence: 99%

A Probabilistic Approach with Built-in Uncertainty Quantification for the Calibration of a Superelastic Constitutive Model from Full-field Strain Data

Paranjape¹,

Aycock²,

Bonsignore³

et al. 2019

Preprint

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Superelastic Nitinol is a widely used material to manufacture implantable medical devices. Simulations are extensively used in the design, optimization, and durability assessment of Nitinol implants. The constitutive response of superelastic materials is non-linear, anisotropic, and asymmetric in tension vs. compression. The existing methods to determine the superelastic material properties used in finite element simulations typically do not account for some of these complexities. The goal of this work is to introduce a method to determine the superelastic material constitutive properties using full-field surface strain measurements. We propose using digital image correlation to obtain surface strain fields during tensile testing of specially designed diamond specimens. The material properties are determined by minimizing a difference metric defined in terms of the local strain difference and the global load difference between the experiment and trial simulations. We also propose a metric in terms of the local strain difference between experimental measurement and simulation prediction to report the credibility of the material properties fitted using this method. The philosophy behind this method and the proposed metric to quantify the accuracy of material property fitting reflects the growing consensus in the implantable device community that the simulation results must be accompanied by a quantification of their credibility.

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Phase transformation volume amplitude as a low-cycle fatigue indicator in nickel–titanium shape memory alloys

Cited by 8 publications

References 16 publications

Full-field microscale strain measurements of a nitinol medical device using digital image correlation

Full-field microscale strain measurements of a nitinol medical device using digital image correlation

Applying Full-Field Measurement Techniques for the Thermomechanical Characterization of Shape Memory Alloys: A Review and Classification

A Probabilistic Approach with Built-in Uncertainty Quantification for the Calibration of a Superelastic Constitutive Model from Full-field Strain Data

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