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Mahmoud Kadkhodaei - One of the best experts on this subject based on the ideXlab platform.
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Phenomenological constitutive modeling of ferromagnetic shape memory alloys considering the effects of Loading History on reorientation start conditions
Continuum Mechanics and Thermodynamics, 2019Co-Authors: Siavash Jafarzadeh, Milad Shirani, Mahmoud Kadkhodaei, Ehsan GheibgholamiAbstract:Ferromagnetic shape memory alloys (FSMAs) are a branch of smart materials which can undergo inelastic deformation when exposed to magnetic fields. In this work, experiments are carried out on an FSMA consisting of elastic interruptions during reorientation to study the effects of Loading History on reorientation start conditions. Correspondingly, a phenomenological approach is introduced to propose appropriate kinetic laws capable of modeling cases in which Loading History plays an important role. Conventional phase diagrams in 2D field–stress space are generalized to 3D reorientation surfaces to directly enter the effects of Loading History on reorientation start conditions. Algebraic approaches are utilized to find conditions guaranteeing the continuation of variant reorientation. Further experiments are also carried out to verify the proposed model under various incomplete Loading–unLoading cycles and minor loops. Comparison between numerical and experimental results indicates the validity of the proposed model. Appropriate continuation conditions for the biaxial Loading case are proposed, and biaxial results are used to verify the proposed model.
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Effect of Loading History on phase transition and martensitic detwinning in shape memory alloys: Limitations of current approaches and development of a 1D constitutive model
Journal of Alloys and Compounds, 2017Co-Authors: Milad Shirani, Mahmoud Kadkhodaei, Masood Taheri Andani, Mohammad ElahiniaAbstract:Abstract Numerous constitutive models have been proposed so far to investigate the unique properties of shape memory alloys. In these models, start conditions for transformation as well as martensitic detwinning are assumed to be independent of Loading History. In this work, experiments are carried out on SMA wires and tubes to show how Loading History affects the transformation and martensitic detwinning start conditions. Based on the experimental findings, enhanced kinetic laws are proposed to consider the effect of Loading History on transformation as well as detwinning start conditions. It is shown that these kinetic laws satisfy the principles of thermodynamics as well. The main feature of the proposed kinetic laws is its simplicity in calculating the amount of martensitic volume fractions. The conventional phase diagrams are further generalized to transformation surfaces in order to directly capture the effects of Loading History. For a specified Loading History, these surfaces in conjunction with geometrical approaches determine the conditions for the beginning of transformations and detwinning. It is shown that the newly-proposed model can successfully reproduce the experimental findings for various incomplete Loading-unLoading cycles on SMA wires and tubes.
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one dimensional constitutive model with transformation surfaces for phase transition in shape memory alloys considering the effect of Loading History
International Journal of Solids and Structures, 2016Co-Authors: Milad Shirani, Mahmoud KadkhodaeiAbstract:Abstract Existing constitutive models for Shape Memory Alloys (SMAs) assume that both forward and reverse transformations occur when the thermodynamic driving force reaches a specific amount regardless of Loading History. In this article, these assumptions are examined, and some cases are introduced where these models predict contradictory results. The effects of initial martensitic volume fraction on both forward and reverse transformations are shown by carrying out simple tensile tests on SMA wires. In line with these experiments, a one-dimensional constitutive model with new transformation conditions is proposed phenomenologically in order to model pseudoelastic behavior. The constitutive model is proved to be consistent with the theory of continuum mechanics. New transformation surfaces are introduced to govern transformations start conditions, rather than using preexisting common phase diagrams. As a result, History-dependent transformation start temperatures are determined. The obtained experimental stress-strain diagrams, available DSC test results, and experimental strain-temperature responses are used to validate the proposed model. It is shown that Loading History affects transformation start conditions.
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A geometrical approach to determine reorientation start and continuation conditions in ferromagnetic shape memory alloys considering the effects of Loading History
Smart Materials and Structures, 2014Co-Authors: Milad Shirani, Mahmoud KadkhodaeiAbstract:Ferromagnetic shape memory alloys (FSMAs) and magnetic shape memory alloys (MSMAs) are metallic alloys that can undergo inelastic responses when exposed to magnetic fields. Several constitutive models have been proposed so far to model the behaviors of FSMAs. In this work, the effects of Loading History on reorientation start conditions are considered, and it is shown that reorientation start conditions are not fixed values; rather, they change with respect to the amount of Loading History. To consider the effects of Loading History on reorientation start conditions, an available phase diagram in stress-field space is generalized to reorientation surfaces in stress-field-Loading History space. Correspondingly, kinetic laws are derived in a continuum framework to be used with the reorientation surfaces to determine the amount of the martensitic variant 2 volume fraction. Based on the geometry of the reorientation surfaces, conditions that must be satisfied to ensure the continuation of reorientations are obtained. Available experimental findings validate the proposed model and the reorientation surfaces.
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A Modified Microplane Model Using Transformation Surfaces to Consider Loading History on Phase Transition in Shape Memory Alloys
Volume 1: Development and Characterization of Multifunctional Materials; Modeling Simulation and Control of Adaptive Systems; Structural Health Monito, 2014Co-Authors: Milad Shirani, Mahmoud Kadkhodaei, Reza Mehrabi, Masood Taheri Andani, Mohammad ElahiniaAbstract:In most of the existing SMA constitutive models, it is assumed that transformation starts when a thermodynamic driving force reaches a specified amount regardless of Loading History. In this work, a phenomenological approach is used to develop an enhanced one-dimensional constitutive model in which Loading History is directly considered as one of the main parameters affecting the transformation start conditions. To generalize the model to three-dimensional cases, a microplane formulation based on volumetric-deviatoric is employed. A free energy potential is defined at the microplane level, integrated over all orientations at a material point to provide the macroscopic free energy. Experiments are carried out on Nitinol superelastic tubes to validate the newly proposed constitutive model. In these experiments, interruptions are applied during transformations to show the effects of Loading History on transformation start conditions. Numerical results are compared with the experimental data to demonstrate the accuracy of the enhanced model.© 2014 ASME
Milad Shirani - One of the best experts on this subject based on the ideXlab platform.
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Phenomenological constitutive modeling of ferromagnetic shape memory alloys considering the effects of Loading History on reorientation start conditions
Continuum Mechanics and Thermodynamics, 2019Co-Authors: Siavash Jafarzadeh, Milad Shirani, Mahmoud Kadkhodaei, Ehsan GheibgholamiAbstract:Ferromagnetic shape memory alloys (FSMAs) are a branch of smart materials which can undergo inelastic deformation when exposed to magnetic fields. In this work, experiments are carried out on an FSMA consisting of elastic interruptions during reorientation to study the effects of Loading History on reorientation start conditions. Correspondingly, a phenomenological approach is introduced to propose appropriate kinetic laws capable of modeling cases in which Loading History plays an important role. Conventional phase diagrams in 2D field–stress space are generalized to 3D reorientation surfaces to directly enter the effects of Loading History on reorientation start conditions. Algebraic approaches are utilized to find conditions guaranteeing the continuation of variant reorientation. Further experiments are also carried out to verify the proposed model under various incomplete Loading–unLoading cycles and minor loops. Comparison between numerical and experimental results indicates the validity of the proposed model. Appropriate continuation conditions for the biaxial Loading case are proposed, and biaxial results are used to verify the proposed model.
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Effect of Loading History on phase transition and martensitic detwinning in shape memory alloys: Limitations of current approaches and development of a 1D constitutive model
Journal of Alloys and Compounds, 2017Co-Authors: Milad Shirani, Mahmoud Kadkhodaei, Masood Taheri Andani, Mohammad ElahiniaAbstract:Abstract Numerous constitutive models have been proposed so far to investigate the unique properties of shape memory alloys. In these models, start conditions for transformation as well as martensitic detwinning are assumed to be independent of Loading History. In this work, experiments are carried out on SMA wires and tubes to show how Loading History affects the transformation and martensitic detwinning start conditions. Based on the experimental findings, enhanced kinetic laws are proposed to consider the effect of Loading History on transformation as well as detwinning start conditions. It is shown that these kinetic laws satisfy the principles of thermodynamics as well. The main feature of the proposed kinetic laws is its simplicity in calculating the amount of martensitic volume fractions. The conventional phase diagrams are further generalized to transformation surfaces in order to directly capture the effects of Loading History. For a specified Loading History, these surfaces in conjunction with geometrical approaches determine the conditions for the beginning of transformations and detwinning. It is shown that the newly-proposed model can successfully reproduce the experimental findings for various incomplete Loading-unLoading cycles on SMA wires and tubes.
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one dimensional constitutive model with transformation surfaces for phase transition in shape memory alloys considering the effect of Loading History
International Journal of Solids and Structures, 2016Co-Authors: Milad Shirani, Mahmoud KadkhodaeiAbstract:Abstract Existing constitutive models for Shape Memory Alloys (SMAs) assume that both forward and reverse transformations occur when the thermodynamic driving force reaches a specific amount regardless of Loading History. In this article, these assumptions are examined, and some cases are introduced where these models predict contradictory results. The effects of initial martensitic volume fraction on both forward and reverse transformations are shown by carrying out simple tensile tests on SMA wires. In line with these experiments, a one-dimensional constitutive model with new transformation conditions is proposed phenomenologically in order to model pseudoelastic behavior. The constitutive model is proved to be consistent with the theory of continuum mechanics. New transformation surfaces are introduced to govern transformations start conditions, rather than using preexisting common phase diagrams. As a result, History-dependent transformation start temperatures are determined. The obtained experimental stress-strain diagrams, available DSC test results, and experimental strain-temperature responses are used to validate the proposed model. It is shown that Loading History affects transformation start conditions.
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A geometrical approach to determine reorientation start and continuation conditions in ferromagnetic shape memory alloys considering the effects of Loading History
Smart Materials and Structures, 2014Co-Authors: Milad Shirani, Mahmoud KadkhodaeiAbstract:Ferromagnetic shape memory alloys (FSMAs) and magnetic shape memory alloys (MSMAs) are metallic alloys that can undergo inelastic responses when exposed to magnetic fields. Several constitutive models have been proposed so far to model the behaviors of FSMAs. In this work, the effects of Loading History on reorientation start conditions are considered, and it is shown that reorientation start conditions are not fixed values; rather, they change with respect to the amount of Loading History. To consider the effects of Loading History on reorientation start conditions, an available phase diagram in stress-field space is generalized to reorientation surfaces in stress-field-Loading History space. Correspondingly, kinetic laws are derived in a continuum framework to be used with the reorientation surfaces to determine the amount of the martensitic variant 2 volume fraction. Based on the geometry of the reorientation surfaces, conditions that must be satisfied to ensure the continuation of reorientations are obtained. Available experimental findings validate the proposed model and the reorientation surfaces.
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A Modified Microplane Model Using Transformation Surfaces to Consider Loading History on Phase Transition in Shape Memory Alloys
Volume 1: Development and Characterization of Multifunctional Materials; Modeling Simulation and Control of Adaptive Systems; Structural Health Monito, 2014Co-Authors: Milad Shirani, Mahmoud Kadkhodaei, Reza Mehrabi, Masood Taheri Andani, Mohammad ElahiniaAbstract:In most of the existing SMA constitutive models, it is assumed that transformation starts when a thermodynamic driving force reaches a specified amount regardless of Loading History. In this work, a phenomenological approach is used to develop an enhanced one-dimensional constitutive model in which Loading History is directly considered as one of the main parameters affecting the transformation start conditions. To generalize the model to three-dimensional cases, a microplane formulation based on volumetric-deviatoric is employed. A free energy potential is defined at the microplane level, integrated over all orientations at a material point to provide the macroscopic free energy. Experiments are carried out on Nitinol superelastic tubes to validate the newly proposed constitutive model. In these experiments, interruptions are applied during transformations to show the effects of Loading History on transformation start conditions. Numerical results are compared with the experimental data to demonstrate the accuracy of the enhanced model.© 2014 ASME
Said Taheri - One of the best experts on this subject based on the ideXlab platform.
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dependence of the cyclic stress strain curve on Loading History and its interaction with fatigue of 304l stainless steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: Adel Belattar, Lakhdar Taleb, Annie Hauet, Said TaheriAbstract:Abstract This study investigates the effects of Loading History on the cyclic stress–strain curve and fatigue behavior of 304L stainless steel at room temperature. Tension–compression tests were performed on the same specimen under controlled strain, using several Loading sequences of increasing or decreasing amplitude. The results show that the cyclic curve is not unique, as it depends on the Loading sequence. The same predeformed specimens were subjected to fatigue tests. The results showed that fatigue life is significantly reduced by the previous Loading History. A previously developed method for determining the effect of prehardening was evaluated. Microstructural analyses were also performed; the microstructures after preLoading and their evolution during the fatigue cycles were characterized by transmission electron microscopy (TEM). The results of these analyses improve our understanding of the macroscopic properties of 304L stainless steel and can help us identify the causes of failure and lifetime reduction.
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Dependence of the cyclic stress–strain curve on Loading History and its interaction with fatigue of 304L stainless steel
Materials Science and Engineering: A, 2012Co-Authors: Adel Belattar, Lakhdar Taleb, Annie Hauet, Said TaheriAbstract:Abstract This study investigates the effects of Loading History on the cyclic stress–strain curve and fatigue behavior of 304L stainless steel at room temperature. Tension–compression tests were performed on the same specimen under controlled strain, using several Loading sequences of increasing or decreasing amplitude. The results show that the cyclic curve is not unique, as it depends on the Loading sequence. The same predeformed specimens were subjected to fatigue tests. The results showed that fatigue life is significantly reduced by the previous Loading History. A previously developed method for determining the effect of prehardening was evaluated. Microstructural analyses were also performed; the microstructures after preLoading and their evolution during the fatigue cycles were characterized by transmission electron microscopy (TEM). The results of these analyses improve our understanding of the macroscopic properties of 304L stainless steel and can help us identify the causes of failure and lifetime reduction.
Shiang-woei Chyuan - One of the best experts on this subject based on the ideXlab platform.
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A study of Loading History effect for thermoviscoelastic solid propellant grains
Computers & Structures, 2000Co-Authors: Shiang-woei ChyuanAbstract:Abstract The results of an investigation on solid propellant grains considering Loading History effect are presented. Traditionally, the thermal Loading History effect of solid propellant grains was not considered for simplifying the analytical task, and a higher safety factor was inevitable for structural integrity. But this does not mean that the thermal Loading History effect is not useful and could be neglected arbitrarily, and this effect usually plays a very important role for some critical design. In order to simulate the time–temperature-dependent behavior of thermoviscoelastic and incompressible polymer materials, concepts of time–temperature shift principle, cumulative damage theory and reduced integration were used. In addition, five different types of thermal Loading History assumption were performed using the finite element method for discussing the thermal Loading History effect. Results show that the thermal Loading History effect is important for structural integrity of solid propellant grains, and improper negligence may cause structural failure of missile systems.
Adel Belattar - One of the best experts on this subject based on the ideXlab platform.
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dependence of the cyclic stress strain curve on Loading History and its interaction with fatigue of 304l stainless steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: Adel Belattar, Lakhdar Taleb, Annie Hauet, Said TaheriAbstract:Abstract This study investigates the effects of Loading History on the cyclic stress–strain curve and fatigue behavior of 304L stainless steel at room temperature. Tension–compression tests were performed on the same specimen under controlled strain, using several Loading sequences of increasing or decreasing amplitude. The results show that the cyclic curve is not unique, as it depends on the Loading sequence. The same predeformed specimens were subjected to fatigue tests. The results showed that fatigue life is significantly reduced by the previous Loading History. A previously developed method for determining the effect of prehardening was evaluated. Microstructural analyses were also performed; the microstructures after preLoading and their evolution during the fatigue cycles were characterized by transmission electron microscopy (TEM). The results of these analyses improve our understanding of the macroscopic properties of 304L stainless steel and can help us identify the causes of failure and lifetime reduction.
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Dependence of the cyclic stress–strain curve on Loading History and its interaction with fatigue of 304L stainless steel
Materials Science and Engineering: A, 2012Co-Authors: Adel Belattar, Lakhdar Taleb, Annie Hauet, Said TaheriAbstract:Abstract This study investigates the effects of Loading History on the cyclic stress–strain curve and fatigue behavior of 304L stainless steel at room temperature. Tension–compression tests were performed on the same specimen under controlled strain, using several Loading sequences of increasing or decreasing amplitude. The results show that the cyclic curve is not unique, as it depends on the Loading sequence. The same predeformed specimens were subjected to fatigue tests. The results showed that fatigue life is significantly reduced by the previous Loading History. A previously developed method for determining the effect of prehardening was evaluated. Microstructural analyses were also performed; the microstructures after preLoading and their evolution during the fatigue cycles were characterized by transmission electron microscopy (TEM). The results of these analyses improve our understanding of the macroscopic properties of 304L stainless steel and can help us identify the causes of failure and lifetime reduction.
