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Masao Akimoto - One of the best experts on this subject based on the ideXlab platform.

  • placement of the urethral stent made of Shape Memory Alloy in management of benign prostatic hypertrophy for debilitated patients
    The Journal of Urology, 1995
    Co-Authors: Katsushi Mori, Shigehiro Okamoto, Masao Akimoto
    Abstract:

    AbstractPurpose: A new urethral stent made of Shape Memory Alloy was placed to relieve prostatic obstruction in 17 patients in whom other approaches were contraindicated.Materials and Methods: All patients were unable to tolerate intervention with sedation and positioning. Placement of the Shape Memory Alloy stent mounted on a 16F Foley catheter is similar to insertion of a urethral catheter except for the heat-sensitive expansion.Results: Each device was easily implanted with the patient on a flat examination Table 1. There was no migration or incrustation of the Shape Memory Alloy stent during the indwelling period.Conclusions: Clinical results demonstrate that the Shape Memory Alloy urethral stent might be the only choice for management of prostatic obstruction in debilitated patients.

Shuichi Miyazaki - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Heat Treatment Condition on Texture in Ti-Mo-Al-Zr Shape Memory Alloy
    Advanced Materials Research, 2014
    Co-Authors: Sasaki Tomoya, Shuichi Miyazaki, Katsunori Hiramatsu, Masaki Tahara, Hideki Hosoda, Tomonari Inamura
    Abstract:

    Effect of solution-treatment condition on texture of a Ti-Mo-Al-Zr Shape Memory Alloy was investigated by X-ray pole figure measurement. Ti-Mo-Al-Zr Alloy is a Ni-free and β-Ti based biomedical Shape Memory Alloy. Unlike Ti-Nb system Alloys, {110}β β recrystallization texture was developed by the solution-treatment above β-transus as the reduction rate increases. However, this texture disappeared by the solution-treatment below β-transus and {531}β β recrystallization texture was strongly developed. It was found that precipitation of hcp α phase has a significant effect on recrystallization texture in this Alloy.

  • effect of cold rolling rate on texture in ti mo al zr Shape Memory Alloy
    Materials Science Forum, 2013
    Co-Authors: Katsunori Hiramatsu, Masaki Tahara, Hideki Hosoda, Tomonari Inamura, Shuichi Miyazaki
    Abstract:

    Effect of rolling rate on texure of Ti-Mo-Al-Zr Shape Memory Alloy was investigated using X-ray diffraction pole figure measurement and electron backscattering pattern (EBSP) analysis to optimize the thermomechanical processing. Ti-Mo-Al-Zr Alloy is a candidate Ni-free Shape Memory Alloy to replace Ti-Ni Alloy in medical applications. The Alloy was single phase of β before rolling and then α''-martensite was induced during the cold-rolling. Unlike the recrystallization texture in Ti-Nb Alloy system, {110}ββ recrystallization texture of β-phase was developed by the solution-treatment especially in the specimens with the reduction rate higher than 90%. This texture has never been observed in Ti-Nb based Alloys and can exhibit a larger recovery strain in both tension and compression.

  • Experimental methodology for TiNi Shape Memory Alloy testing under complex stress state
    Archives of Mechanics, 1999
    Co-Authors: B. Raniecki, L. Dietrich, Zbigniew L. Kowalewski, G. Socha, Shuichi Miyazaki, K. Tanaka, Andrzej Ziolkowski
    Abstract:

    THE EXPERIMENTAL METHOD and preliminary results of multiaxial proportional loadings at a range of different temperatures are discussed for the TiNi Shape Memory Alloy. The results are limited to the R-phase reorientation and transformation pseudoelasticity of the material tested at the selected constant temperatures. The main objective of the paper is to develop experimental knowledge of the Shape Memory Alloy properties under complex stress states which would allow better understanding of the material behaviour and create a basis for theoretical modelling.

Jacob Aboudi - One of the best experts on this subject based on the ideXlab platform.

  • Micromechanical prediction of the two-way Shape Memory effect in Shape Memory Alloy composites
    International Journal of Solids and Structures, 2009
    Co-Authors: Yuval Freed, Jacob Aboudi
    Abstract:

    AbstractThe two-way Shape Memory effect in monolithic Shape Memory Alloys has been widely investigated both theoretically and experimentally. In the present study, this effect is analyzed for Shape Memory Alloy composites by employing a micromechanical model. To this end, the responses of polymeric matrix and metal matrix unidirectional composites with embedded Shape Memory Alloy fibers are determined. For the polymeric matrix composite, the effect of axial, transverse and shear loadings as well as the fiber volume fraction on the resulting two-way Shape Memory behavior are studied. The local distributions of stresses among the Shape Memory Alloy fiber and epoxy matrix in the low- and high-temperature Shapes of the composite are also investigated. Two training procedures that generate the two-way Shape Memory effect in the metal matrix composite are offered. The present analysis shows that the two-way Shape Memory effect in the chosen type of metal matrix composite is not as useful as in the polymeric matrix one. Finally, for a polymeric matrix composite that is subjected to a transverse normal loading, the effect of imperfect bonding between the Shape Memory Alloy fibers and the neighboring matrix is investigated

  • Thermomechanically micromechanical modeling of prestressed concrete reinforced with Shape Memory Alloy fibers
    Smart Materials and Structures, 2007
    Co-Authors: Yuval Freed, Jacob Aboudi, Rivka Gilat
    Abstract:

    Concrete is a very popular material in civil engineering, although it exhibits some limitations. The most crucial limitation is its low tensile strength, compared to its compressive strength, which results from the propagation of micro-cracks. This may be prevented by using prestrained Shape Memory Alloy wires that are embedded in the concrete matrix. Upon activation, these wires regain their original Shape, and consequently initial compressive stresses are transmitted to the concrete matrix. In this study, a thermomechanically micromechanical model of prestressed concrete reinforced by Shape Memory Alloy fibers is presented and examined for different reinforcement aspects. It was found that there is a strong relation between the activation temperature deviation and the behavior of the prestressed concrete. The relation between the fiber's volume fraction and the composite response and the effect of the Shape of the reinforcing fibers and residual strain orientations is examined in detail.

  • The response of Shape Memory Alloy composites
    Smart Materials and Structures, 1997
    Co-Authors: Jacob Aboudi
    Abstract:

    A microstructural model that couples the local and global effects is employed to analyse the behavior of composite materials with Shape Memory Alloy fibers. Both metallic matrices and resin matrix composites with embedded Shape Memory Alloy fibers are considered. Since Shape Memory Alloys form fibers with large diameter, this model is particularly suitable for the analysis of this type of smart composite material where the coupling between the microstructural details and the macrostructure of the composite must be incorporated. Results are given that exhibit the response of composites with embedded Shape Memory Alloy fibers in various circumstances.

Yang Shu - One of the best experts on this subject based on the ideXlab platform.

  • PLACEMENT OF THE URETHRAL STENT MADE OF Shape Memory Alloy IN MANAGEMENT OF BENIGN PROSTATIC HYPERPLASIA
    Journal of Hebei Medical University, 2002
    Co-Authors: Yang Shu
    Abstract:

    ObjectiveTo evaluate the effect and saft y of Shape Memory Alloy stents on the treatment of benign prostatic hyperplasia(BPH).MethodsThe temperature sensitive Shape Memory Alloy urethral stents were inserted with special device for the relief of prostate obstruction in 52 cases of BPH.ResultsAmong 52 cases,45 cases were successfully inserted at the first try,7 cases were failed and had to use alternative method for the insertion.As 9-25 months following up results have showed that the maximum flow was increased form ( 3.9 ～ 6.5 )ml/s to 12 ml/s.Side effect were not appeared in patients treated with insertion.ConclusionTransurethral placement of Memory Alloy stents is a safe, effective method for treatment of prostatic obstruction, especially in ager or high risk patients who could not toleranced operation.

Darren J. Hughes - One of the best experts on this subject based on the ideXlab platform.

  • Internal stresses in steel plate generated by Shape Memory Alloy inserts
    Acta Materialia, 2012
    Co-Authors: Benoit Malard, Jan Pilch, Petr Sittner, Vadim Davydov, Petr Sedlák, K. Konstantinidis, Darren J. Hughes
    Abstract:

    Neutron strain scanning was employed to investigate the internal stress fields in steel plate coupons with embedded prestrained superelastic NiTi Shape Memory Alloy inserts. Strain fields in steel were evaluated at T = 21 °C and 130 °C on virgin coupons as well as on mechanically and thermally fatigued coupons. Internal stress fields were evaluated by direct calculation of principal stress components from the experimentally measured lattice strains as well as by employing an inverse finite element modeling approach. It is shown that if the NiTi inserts are embedded into the elastic steel matrix following a carefully designed technological procedure, the internal stress fields vary with temperature in a reproducible and predictable way. It is estimated that this mechanism of internal stress generation can be safely applied in the temperature range from -20 °C to 150 °C and is relatively resistant to thermal and mechanical fatigue. The predictability and fatigue endurance of the mechanism are of essential importance for the development of future smart metal matrix composites or smart structures with embedded Shape Memory Alloy components.

  • Internal stresses in steel plate generated by Shape Memory Alloy inserts.
    Acta Materialia, 2012
    Co-Authors: Benoit Malard, Jan Pilch, Petr Sittner, Vadim Davydov, Petr Sedlák, K. Konstantinidis, Darren J. Hughes
    Abstract:

    Neutron strain scanning was employed to investigate the internal stress fields in steel plate coupons with embedded prestrained super-elastic NiTi Shape Memory Alloy inserts. Strain fields in steel were evaluated at T = 21 degrees C and 130 degrees C on virgin coupons as well as on mechanically and thermally fatigued coupons. Internal stress fields were evaluated by direct calculation of principal stress components from the experimentally measured lattice strains as well as by employing an inverse finite element modeling approach. It is shown that if the NiTi inserts are embedded into the elastic steel matrix following a carefully designed technological procedure, the internal stress fields vary with temperature in a reproducible and predictable way. It is estimated that this mechanism of internal stress generation can be safely applied in the temperature range from -20 degrees C to 150 degrees C and is relatively resistant to thermal and mechanical fatigue. The predictability and fatigue endurance of the mechanism are of essential importance for the development of future smart metal matrix composites or smart structures with embedded Shape Memory Alloy components.