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Carmine Maletta - One of the best experts on this subject based on the ideXlab platform.

  • Analytical modeling of stress-induced martensitic transformation in the Crack Tip Region of nickel–titanium alloys
    Acta Materialia, 2020
    Co-Authors: Carmine Maletta, Franco Furgiuele
    Abstract:

    Abstract A novel analytical method, which predicts the extent of the stress-induced martensitic transformation (SIM) in the Crack Tip vicinity of nickel–titanium (NiTi)-based shape memory alloys, as well as describing the stress distribution in both transformed and untransformed Regions, is presented. The method has been validated by comparisons with results from finite-element simulations with good agreement. Furthermore, the method has been used to analyze the effects of various thermomechanical parameters on the extent of the transformation Region near the Crack Tip. Finally, the effects of several thermomechanical loading conditions, in terms of both applied stress and temperature, on the Crack Tip transformation behavior have been analyzed. The results highlight a marked effect of temperature on the extent of the transformation Region and, consequently, on the Crack Tip stress distribution. As a consequence, temperature plays a role in the fracture process of NiTi alloys.

  • Crack-Tip thermal and mechanical hysteresis in Shape Memory Alloys under fatigue loading
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014
    Co-Authors: Carmine Maletta, Luigi Bruno, P. Corigliano, Vincenzo Crupi, Eugenio Guglielmino
    Abstract:

    Crack Tip stress-induced phase transformation mechanisms in nickel–titanium alloys (NiTi), subjected to fatigue mechanical loads, have been analyzed by full field measurement techniques. In particular, Infrared thermography (IR) and Digital Image Correlation (DIC), have been applied to analyze the cyclic temperature and displacement evolutions in the Crack Tip Region of a commercial pseudoelastic alloy, together with the associated thermal and mechanical hysteresis, by using Single Edge Crack (SEC) specimens. IR investigations revealed a global temperature variation of the specimen due to Crack formation and propagation mechanisms, which is similar to common engineering metals, i.e. surface temperature rises quickly in an initial phase, then it reaches an almost constant value, and finally it increases rapidly as a consequence of the fatigue Crack growth. In addition, cyclic thermal variation in the Crack Tip Region and related hysteresis (temperature vs load) has been measured, which can been directly related to the thermal effects of the reversible stress-induced phase transformations. Furthermore, a proper experimental setup has been made, based on a reflection microscope, for direct measurements of the Crack Tip displacement field by the DIC technique. Furthermore, a fitting procedure has been developed to calculate the mode I Stress Intensity Factor (SIF), starting from the displacement field, and the related mechanical hysteresis (SIF vs load).

  • analytical modeling of stress induced martensitic transformation in the Crack Tip Region of nickel titanium alloys
    Acta Materialia, 2010
    Co-Authors: Carmine Maletta, Franco Furgiuele
    Abstract:

    Abstract A novel analytical method, which predicts the extent of the stress-induced martensitic transformation (SIM) in the Crack Tip vicinity of nickel–titanium (NiTi)-based shape memory alloys, as well as describing the stress distribution in both transformed and untransformed Regions, is presented. The method has been validated by comparisons with results from finite-element simulations with good agreement. Furthermore, the method has been used to analyze the effects of various thermomechanical parameters on the extent of the transformation Region near the Crack Tip. Finally, the effects of several thermomechanical loading conditions, in terms of both applied stress and temperature, on the Crack Tip transformation behavior have been analyzed. The results highlight a marked effect of temperature on the extent of the transformation Region and, consequently, on the Crack Tip stress distribution. As a consequence, temperature plays a role in the fracture process of NiTi alloys.

  • stress induced martensitic transformation in the Crack Tip Region of a niti alloy
    Journal of Materials Engineering and Performance, 2009
    Co-Authors: A Falvo, Franco Furgiuele, A Leonardi, Carmine Maletta
    Abstract:

    The evolution of stress-induced martensitic transformation in front of the Crack Tip in a NiTi alloy is analyzed in this investigation, by two-dimensional finite element simulations of single edge-Crack specimens. In particular, the transformation start and finish contours, i.e., the boundaries of the transformation zone, were obtained by using plasticity concepts, and the effects of the temperature were taken into account by using the Clausius-Clapeyron relation. Furthermore, comparisons between numerical and analytical results, obtained by Irwin’s modified linear elastic fracture mechanics relations, were carried out. These comparisons show that a good agreement in terms of the martensite start and finish sizes is obtained; moreover, the analytic approach could be able to describe the stress field in the Crack Tip Region outside the phase transformation zone, i.e., in the austenitic Region, but a proper equation to estimate the effective Crack length should be found. To this aim, further studies should be carried out.

Franco Furgiuele - One of the best experts on this subject based on the ideXlab platform.

  • Analytical modeling of stress-induced martensitic transformation in the Crack Tip Region of nickel–titanium alloys
    Acta Materialia, 2020
    Co-Authors: Carmine Maletta, Franco Furgiuele
    Abstract:

    Abstract A novel analytical method, which predicts the extent of the stress-induced martensitic transformation (SIM) in the Crack Tip vicinity of nickel–titanium (NiTi)-based shape memory alloys, as well as describing the stress distribution in both transformed and untransformed Regions, is presented. The method has been validated by comparisons with results from finite-element simulations with good agreement. Furthermore, the method has been used to analyze the effects of various thermomechanical parameters on the extent of the transformation Region near the Crack Tip. Finally, the effects of several thermomechanical loading conditions, in terms of both applied stress and temperature, on the Crack Tip transformation behavior have been analyzed. The results highlight a marked effect of temperature on the extent of the transformation Region and, consequently, on the Crack Tip stress distribution. As a consequence, temperature plays a role in the fracture process of NiTi alloys.

  • analytical modeling of stress induced martensitic transformation in the Crack Tip Region of nickel titanium alloys
    Acta Materialia, 2010
    Co-Authors: Carmine Maletta, Franco Furgiuele
    Abstract:

    Abstract A novel analytical method, which predicts the extent of the stress-induced martensitic transformation (SIM) in the Crack Tip vicinity of nickel–titanium (NiTi)-based shape memory alloys, as well as describing the stress distribution in both transformed and untransformed Regions, is presented. The method has been validated by comparisons with results from finite-element simulations with good agreement. Furthermore, the method has been used to analyze the effects of various thermomechanical parameters on the extent of the transformation Region near the Crack Tip. Finally, the effects of several thermomechanical loading conditions, in terms of both applied stress and temperature, on the Crack Tip transformation behavior have been analyzed. The results highlight a marked effect of temperature on the extent of the transformation Region and, consequently, on the Crack Tip stress distribution. As a consequence, temperature plays a role in the fracture process of NiTi alloys.

  • stress induced martensitic transformation in the Crack Tip Region of a niti alloy
    Journal of Materials Engineering and Performance, 2009
    Co-Authors: A Falvo, Franco Furgiuele, A Leonardi, Carmine Maletta
    Abstract:

    The evolution of stress-induced martensitic transformation in front of the Crack Tip in a NiTi alloy is analyzed in this investigation, by two-dimensional finite element simulations of single edge-Crack specimens. In particular, the transformation start and finish contours, i.e., the boundaries of the transformation zone, were obtained by using plasticity concepts, and the effects of the temperature were taken into account by using the Clausius-Clapeyron relation. Furthermore, comparisons between numerical and analytical results, obtained by Irwin’s modified linear elastic fracture mechanics relations, were carried out. These comparisons show that a good agreement in terms of the martensite start and finish sizes is obtained; moreover, the analytic approach could be able to describe the stress field in the Crack Tip Region outside the phase transformation zone, i.e., in the austenitic Region, but a proper equation to estimate the effective Crack length should be found. To this aim, further studies should be carried out.

A Falvo - One of the best experts on this subject based on the ideXlab platform.

  • stress induced martensitic transformation in the Crack Tip Region of a niti alloy
    Journal of Materials Engineering and Performance, 2009
    Co-Authors: A Falvo, Franco Furgiuele, A Leonardi, Carmine Maletta
    Abstract:

    The evolution of stress-induced martensitic transformation in front of the Crack Tip in a NiTi alloy is analyzed in this investigation, by two-dimensional finite element simulations of single edge-Crack specimens. In particular, the transformation start and finish contours, i.e., the boundaries of the transformation zone, were obtained by using plasticity concepts, and the effects of the temperature were taken into account by using the Clausius-Clapeyron relation. Furthermore, comparisons between numerical and analytical results, obtained by Irwin’s modified linear elastic fracture mechanics relations, were carried out. These comparisons show that a good agreement in terms of the martensite start and finish sizes is obtained; moreover, the analytic approach could be able to describe the stress field in the Crack Tip Region outside the phase transformation zone, i.e., in the austenitic Region, but a proper equation to estimate the effective Crack length should be found. To this aim, further studies should be carried out.

Xiao Zhi Hu - One of the best experts on this subject based on the ideXlab platform.

A Leonardi - One of the best experts on this subject based on the ideXlab platform.

  • stress induced martensitic transformation in the Crack Tip Region of a niti alloy
    Journal of Materials Engineering and Performance, 2009
    Co-Authors: A Falvo, Franco Furgiuele, A Leonardi, Carmine Maletta
    Abstract:

    The evolution of stress-induced martensitic transformation in front of the Crack Tip in a NiTi alloy is analyzed in this investigation, by two-dimensional finite element simulations of single edge-Crack specimens. In particular, the transformation start and finish contours, i.e., the boundaries of the transformation zone, were obtained by using plasticity concepts, and the effects of the temperature were taken into account by using the Clausius-Clapeyron relation. Furthermore, comparisons between numerical and analytical results, obtained by Irwin’s modified linear elastic fracture mechanics relations, were carried out. These comparisons show that a good agreement in terms of the martensite start and finish sizes is obtained; moreover, the analytic approach could be able to describe the stress field in the Crack Tip Region outside the phase transformation zone, i.e., in the austenitic Region, but a proper equation to estimate the effective Crack length should be found. To this aim, further studies should be carried out.