Design and thermo-mechanical analysis of a new NiTi shape memory alloy fixing clip

Nespoli, Adelaide; Dallolio, Villiam; Stortiero, Francesco; Besseghini, S.; Passaretti, Francesca; Villa, Elena

doi:10.1016/j.msec.2014.01.001

Cited by 13 publications

(7 citation statements)

References 13 publications

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“…In some medical uses, we can find one more great class of SMAs, commercially known as body temperature (B) alloys, which have Af very close to the human body temperature and that need an extra heating to complete the transformation into the austenite phase [17][18][19][20][21][22]. After the implantation in a human being, the B-type SMA remains in the austenite state and performs according to the flagshaped pseudoelastic behavior.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

A new design of a Nitinol ring-like wire for suturing in deep surgical field

Nespoli

Dallolio²,

Villa

et al. 2015

Materials Science and Engineering: C

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Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

A new design of a Nitinol ring-like wire for suturing in deep surgical field

Nespoli

Dallolio²,

Villa

et al. 2015

Materials Science and Engineering: C

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“…The first medical application of NiTi alloy was orthodontic archwires in the early 1970s [1]. NiTi is composed of near equiatomic ratios of Ni and Ti, where the high temperature stable parent phase B2-Austenite may transform to the low temperature stable phase B19-Martensite through a thermoelastic martensitic transition (TMT) [2][3][4][5][6]. For medical applications NiTi is often used as in the austenite state, taking advantage of its pseudoelasticity, a reversible elastic response to applied stress through twinning (Figure 1a), with elastic strain of up to 10% [7,8].…”

Section: Introductionmentioning

confidence: 99%

Biomedical NiTi and β-Ti Alloys: From Composition, Microstructure and Thermo-Mechanics to Application

Nespoli

Passaretti

Szentmiklósi

et al. 2022

Metals

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A comprehensive, bottoms-up characterization of two of the most widely used biomedical Ti-containing alloys, NiTi and β-Ti, was carried out applying a novel combination of neutron diffraction, neutron prompt-gamma activation, surface morphology, thermal analysis and mechanical tests, to relate composition, microstructure and physical-chemical-mechanical properties to unknown processing history. The commercial specimens studied are rectangular (0.43 × 0.64 mm~0.017 × 0.025 inch) wires, in both pre-formed U-shape and straight extended form. Practical performance was quantitatively linked to the influence of alloying elements, microstructure and thermo-mechanical processing. Results demonstrated that the microstructure and phase composition of β-Ti strongly depended on the composition, phase-stabilizing elements in particular, in that the 10.2 wt.% Mo content in Azdent resulted in 41.2% α phase, while Ormco with 11.6 wt.% Mo contained only β phase. Although the existence of α phase is probable in the meta-stable alloy, the α phase has never been quantified before. Further, the phase transformation behavior of NiTi directly arose from the microstructure, whilst being highly influenced by thermo-mechanical history. A strong correlation (r = 0.878) was established between phase transformation temperature and the force levels observed in bending test at body temperature, reconfirming that structure determines performance, while also being highly influenced by thermo-mechanical history. The novel methodology described is evidenced as generating a predictive profile of the eventual biomechanical properties and practical performance of the commercial materials. Overall, the work encompasses a reproducible and comprehensive approach expected to aid in future optimization and rational design of devices of metallic origin.

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“…In the orthodontic field, as well as in the most SMA biomedical applications [11][12][13][14][15], SMA are used for their pseudoelastic property. For pseudoelastic materials, the transition between the two characteristic phases happens under an external load and it occurs always at a temperature higher than the austenite finishing one (Af).…”

Section: Introductionmentioning

confidence: 99%

DSC and three-point bending test for the study of the thermo-mechanical history of NiTi and NiTi-based orthodontic archwires

Nespoli

Villa

Bergo

et al. 2015

J Therm Anal Calorim

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It is a known fact that the NiTi orthodontic archwire is one of the first and most diffuse biomedical applications of shape memory alloys. In the last years, none deep study about orthodontic archwires has been conducted from the material point of view. In general, the clinical response is the principal aspect that has been investigated for this application. Nonetheless, the accurate mechanical and physical characterization of the archwires can be very important to add new developments to this biomedical product and to give a substantial contribution to the indispensable evolution that is crucial for better clinic results. In fact, the principal aspect that it is needed for further improvements is the study of the optimal force that does not cause damage to the surrounding tissues. According to this statement, a deep study about the thermomechanical characterization of several pseudoelastic commercial archwires used in the straight-wire low-friction techniques is presented. In detail, flexural mechanical tests in the three-point-bending configuration were conducted to assess the archwires unloading force, while differential scanning calorimetry was used to study the phase transition temperatures, and the thermo-mechanical history of each specimen. Both NiTi and NiTiCu commercial archwires were tested, and different geometries were considered. For all the archwires, an excellent repeatability of the results has been found. This series of characterizations provides a complete view of the thermo-mechanical properties of the material, and therefore it shows the possibility to modulate the functional properties developed by the device as a function of the biological field.

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Design and thermo-mechanical analysis of a new NiTi shape memory alloy fixing clip

Cited by 13 publications

References 13 publications

A new design of a Nitinol ring-like wire for suturing in deep surgical field

A new design of a Nitinol ring-like wire for suturing in deep surgical field

Biomedical NiTi and β-Ti Alloys: From Composition, Microstructure and Thermo-Mechanics to Application

DSC and three-point bending test for the study of the thermo-mechanical history of NiTi and NiTi-based orthodontic archwires

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