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Papers by olfa daghfas

Research paper thumbnail of Anisotropic Study of Behavior of Titanium Alloy Thin Sheets Using Identification Strategy

The objective of this work is to provide an operational model for the numerical simulation of the... more The objective of this work is to provide an operational model for the numerical simulation of the shaping processes by plastic deformation of thin plates made of Titanium alloy. Hence, the importance of developing a general framework of elastoplastic orthotropic models (initial orthotropy and isotropic hardening) based on the choice of an equivalent stress, a law of hardening for the development of a strategy of identification of the model from an experimental database. At this level, the identification of the constitutive parameters involved in the laws of behavior of the materials represents an important step in this work. A new identification strategy accompanied by its validation using the criterion of Barlat will be proposed. Numerical simulation can be a very useful tool for titanium alloy. Mainly due to its use in orthopedic surgery; Titanium is of great interest because of its elasticity modulus very close to that of the bone.

Research paper thumbnail of Numerical Analysis of Kinematic Hardening Effect in Cyclic Loading of Aluminum Alloy 2024

Advances in Mechanical Engineering and Mechanics II, 2021

Research paper thumbnail of Anisotropic Study of Behavior of Titanium Alloy Thin Sheets Using Identification Strategy

Lecture Notes in Mechanical Engineering, Nov 25, 2017

The objective of this work is to provide an operational model for the numerical simulation of the... more The objective of this work is to provide an operational model for the numerical simulation of the shaping processes by plastic deformation of thin plates made of Titanium alloy. Hence, the importance of developing a general framework of elastoplastic orthotropic models (initial orthotropy and isotropic hardening) based on the choice of an equivalent stress, a law of hardening for the development of a strategy of identification of the model from an experimental database. At this level, the identification of the constitutive parameters involved in the laws of behavior of the materials represents an important step in this work. A new identification strategy accompanied by its validation using the criterion of Barlat will be proposed. Numerical simulation can be a very useful tool for titanium alloy. Mainly due to its use in orthopedic surgery; Titanium is of great interest because of its elasticity modulus very close to that of the bone.

Research paper thumbnail of Theorical study on mechanical properties of AZ31B Magnesium alloy Sheets under multiaxial loading

Frattura ed Integrità Strutturale, Oct 3, 2016

Numerical simulation by plastic deformation of the shaping processes currently has a large indust... more Numerical simulation by plastic deformation of the shaping processes currently has a large industrial interest. It allows you to shorten the time of design and construction related products and tools to analyze and to optimize processes. An essential part of simulation tools is the constitutive law used to describe the material used. The activity of characterization and modeling of material behavior of the plastic deformation shaping remains a very important research field of activity; the objective of proposing laws of behavior used in computer codes, essentially based on finite element is sufficiently to represent the real behavior of materials. Considering the nature of the materials used and the stresses they experience the behavior laws account for several requirements which make them increasingly complicated. Among these requirements, we cite in particular plastic anisotropy, the great transformations, the complexity and diversity of loads, etc. The complexity of these laws makes them more difficult to implement and in particular to identify: the classic tests are no longer sufficient for identification. The objective of this work is based on two essential points: Suggest a construction strategy, particularly of identifying laws elastoplastic behavior anisotropic operational for the numerical simulation of plastic deformation shaping processes with particular attention to sheet metal magnesium. Magnesium sheet metal manufacturing process involves rolling operation. In a cost-cutting goal, this operation now takes place cold, implying a very marked anisotropy of the material at the output of the mill.

Research paper thumbnail of Experimental and numerical study on mechanical properties of aluminum alloy under uniaxial tensile test

Fracture and Structural Integrity, 2016

The main objective is to model the behavior of 7075 aluminum alloy and built an experimental data... more The main objective is to model the behavior of 7075 aluminum alloy and built an experimental database to identify the model parameters. The first part of the paper presents an experimental database on 7075 aluminum alloy. Thus, uniaxial tensile tests are carried in three loading directions relative to the rolling direction, knowing that the fatigue of aircraft structures is traditionally managed based on the assumption of uniaxial loads. From experimental database, the mechanical properties are extracted, particularly the various fractures owing to pronounced anisotropy relating to material. In second part, plastic anisotropy is then modeled using the identification strategy which depends on yield criteria, hardening law and evolution law. In third part, a comparison with experimental data shows that behavior model can successfully describe the anisotropy of the Lankford coefficient.

Research paper thumbnail of Evolution of Mechanical Behavior of Aluminum Alloy Al 7075 during Maturation Time

The Aluminum 7075 (Al 7075) alloy is a precipitation hardening material instead of a strain harde... more The Aluminum 7075 (Al 7075) alloy is a precipitation hardening material instead of a strain hardening material. These mechanical properties are of a particular microstructure obtained by thermo-mechanical treatments. Among other things, this is a complicated microstructure which is responsible for the mechanical performance. The evolution of the mechanical properties of aluminum alloys is dependent on aging time parameters after heat treatment. In this study, the material has undergone a tempering heat treatment followed by a series of tensile tests. The experimental data (tensile curves in three directions during maturation time) is used to describe the evolution of the mechanical characteristics in terms of loading directions and maturation time, denoted respectively as: Ψ and t. The tensile curves are the source of data to begin the problem of identifying the behavior law of studied material using Barlat’s model and Hollomon’s isotropic hardening law. Thus, from the identified pa...

Research paper thumbnail of Isotropic and Kinematic Hardening Laws: Plastic Behavior of Mild Steel Under Shear Tests

Advances in Mechanical Engineering and Mechanics II

Research paper thumbnail of Modeling of TA6V Titanium Alloy by an Identification Strategy: Biomechanical Application

Advances in Mechanical Engineering and Mechanics II

Research paper thumbnail of Mechanical behavior of materials with a compact hexagonal structure obtained by an advanced identification strategy of HCP material, AZ31B-H24

Frattura ed Integrità Strutturale

Research paper thumbnail of Identification strategy of anisotropic behavior laws: application to thin sheets of Aluminium A5

Journal of Theoretical and Applied Mechanics

Numerical simulation provides a valuable assistance in the controlling of forming processes. The ... more Numerical simulation provides a valuable assistance in the controlling of forming processes. The elasto-plastic orthotropic constitutive law is based on the choice of an equivalent stress, a hardening law and a plastic potential. An identification of the model parameters from an experimental database is developed. This database consists in hardening curves and Lankford coefficients of specimens subjected to off-axis tensile tests. The proposed identification strategy is applied to aluminum sheets. The behavior of this material is studied under several solicitations. The anisotropic behavior of the aluminum plate is modeled using the Barlat criterionand the hardening law. The obtained Lankford coefficients are compared to those which are identified by a different strategy.

Research paper thumbnail of Experimental Study on Mechanical Properties of Aluminum Alloys under Uniaxial Tensile Tests

International Journal of Technology

Research paper thumbnail of Evolution of Mechanical Behavior of Aluminum Alloy Al 7075 during Maturation Time

International Journal of Technology, 2016

The Aluminum 7075 (Al 7075) alloy is a precipitation hardening material instead of a strain harde... more The Aluminum 7075 (Al 7075) alloy is a precipitation hardening material instead of a strain hardening material. These mechanical properties are of a particular microstructure obtained by thermo-mechanical treatments. Among other things, this is a complicated microstructure which is responsible for the mechanical performance. The evolution of the mechanical properties of aluminum alloys is dependent on aging time parameters after heat treatment. In this study, the material has undergone a tempering heat treatment followed by a series of tensile tests. The experimental data (tensile curves in three directions during maturation time) is used to describe the evolution of the mechanical characteristics in terms of loading directions and maturation time, denoted respectively as: Ψ and t. The tensile curves are the source of data to begin the problem of identifying the behavior law of studied material using Barlat's model and Hollomon's isotropic hardening law. Thus, from the identified parameters (anisotropy coefficients and hardening coefficients), the evolution of the Lankford coefficient, deformation rate and load surfaces during the maturation time for three load directions (0°: rolling direction, 45° and 90°) are described. This study allows optimizing the response of the aluminum alloy to plastic strains, resulting from forming processes measured against the best time during maturation and the best load direction.

Research paper thumbnail of Identification strategy of anisotropic behavior laws: application to thin sheets of Aluminium A5

Journal of Theoretical and Applied Mechanics

Numerical simulation provides a valuable assistance in the controlling of forming processes. The ... more Numerical simulation provides a valuable assistance in the controlling of forming processes. The elasto-plastic orthotropic constitutive law is based on the choice of an equivalent stress, a hardening law and a plastic potential. An identification of the model parameters from an experimental database is developed. This database consists in hardening curves and Lankford coefficients of specimens subjected to off-axis tensile tests. The proposed identification strategy is applied to aluminum sheets. The behavior of this material is studied under several solicitations. The anisotropic behavior of the aluminum plate is modeled using the Barlat criterionand the hardening law. The obtained Lankford coefficients are compared to those which are identified by a different strategy.

Research paper thumbnail of Anisotropic Study of Behavior of Titanium Alloy Thin Sheets Using Identification Strategy

The objective of this work is to provide an operational model for the numerical simulation of the... more The objective of this work is to provide an operational model for the numerical simulation of the shaping processes by plastic deformation of thin plates made of Titanium alloy. Hence, the importance of developing a general framework of elastoplastic orthotropic models (initial orthotropy and isotropic hardening) based on the choice of an equivalent stress, a law of hardening for the development of a strategy of identification of the model from an experimental database. At this level, the identification of the constitutive parameters involved in the laws of behavior of the materials represents an important step in this work. A new identification strategy accompanied by its validation using the criterion of Barlat will be proposed. Numerical simulation can be a very useful tool for titanium alloy. Mainly due to its use in orthopedic surgery; Titanium is of great interest because of its elasticity modulus very close to that of the bone.

Research paper thumbnail of Numerical Analysis of Kinematic Hardening Effect in Cyclic Loading of Aluminum Alloy 2024

Advances in Mechanical Engineering and Mechanics II, 2021

Research paper thumbnail of Anisotropic Study of Behavior of Titanium Alloy Thin Sheets Using Identification Strategy

Lecture Notes in Mechanical Engineering, Nov 25, 2017

The objective of this work is to provide an operational model for the numerical simulation of the... more The objective of this work is to provide an operational model for the numerical simulation of the shaping processes by plastic deformation of thin plates made of Titanium alloy. Hence, the importance of developing a general framework of elastoplastic orthotropic models (initial orthotropy and isotropic hardening) based on the choice of an equivalent stress, a law of hardening for the development of a strategy of identification of the model from an experimental database. At this level, the identification of the constitutive parameters involved in the laws of behavior of the materials represents an important step in this work. A new identification strategy accompanied by its validation using the criterion of Barlat will be proposed. Numerical simulation can be a very useful tool for titanium alloy. Mainly due to its use in orthopedic surgery; Titanium is of great interest because of its elasticity modulus very close to that of the bone.

Research paper thumbnail of Theorical study on mechanical properties of AZ31B Magnesium alloy Sheets under multiaxial loading

Frattura ed Integrità Strutturale, Oct 3, 2016

Numerical simulation by plastic deformation of the shaping processes currently has a large indust... more Numerical simulation by plastic deformation of the shaping processes currently has a large industrial interest. It allows you to shorten the time of design and construction related products and tools to analyze and to optimize processes. An essential part of simulation tools is the constitutive law used to describe the material used. The activity of characterization and modeling of material behavior of the plastic deformation shaping remains a very important research field of activity; the objective of proposing laws of behavior used in computer codes, essentially based on finite element is sufficiently to represent the real behavior of materials. Considering the nature of the materials used and the stresses they experience the behavior laws account for several requirements which make them increasingly complicated. Among these requirements, we cite in particular plastic anisotropy, the great transformations, the complexity and diversity of loads, etc. The complexity of these laws makes them more difficult to implement and in particular to identify: the classic tests are no longer sufficient for identification. The objective of this work is based on two essential points: Suggest a construction strategy, particularly of identifying laws elastoplastic behavior anisotropic operational for the numerical simulation of plastic deformation shaping processes with particular attention to sheet metal magnesium. Magnesium sheet metal manufacturing process involves rolling operation. In a cost-cutting goal, this operation now takes place cold, implying a very marked anisotropy of the material at the output of the mill.

Research paper thumbnail of Experimental and numerical study on mechanical properties of aluminum alloy under uniaxial tensile test

Fracture and Structural Integrity, 2016

The main objective is to model the behavior of 7075 aluminum alloy and built an experimental data... more The main objective is to model the behavior of 7075 aluminum alloy and built an experimental database to identify the model parameters. The first part of the paper presents an experimental database on 7075 aluminum alloy. Thus, uniaxial tensile tests are carried in three loading directions relative to the rolling direction, knowing that the fatigue of aircraft structures is traditionally managed based on the assumption of uniaxial loads. From experimental database, the mechanical properties are extracted, particularly the various fractures owing to pronounced anisotropy relating to material. In second part, plastic anisotropy is then modeled using the identification strategy which depends on yield criteria, hardening law and evolution law. In third part, a comparison with experimental data shows that behavior model can successfully describe the anisotropy of the Lankford coefficient.

Research paper thumbnail of Evolution of Mechanical Behavior of Aluminum Alloy Al 7075 during Maturation Time

The Aluminum 7075 (Al 7075) alloy is a precipitation hardening material instead of a strain harde... more The Aluminum 7075 (Al 7075) alloy is a precipitation hardening material instead of a strain hardening material. These mechanical properties are of a particular microstructure obtained by thermo-mechanical treatments. Among other things, this is a complicated microstructure which is responsible for the mechanical performance. The evolution of the mechanical properties of aluminum alloys is dependent on aging time parameters after heat treatment. In this study, the material has undergone a tempering heat treatment followed by a series of tensile tests. The experimental data (tensile curves in three directions during maturation time) is used to describe the evolution of the mechanical characteristics in terms of loading directions and maturation time, denoted respectively as: Ψ and t. The tensile curves are the source of data to begin the problem of identifying the behavior law of studied material using Barlat’s model and Hollomon’s isotropic hardening law. Thus, from the identified pa...

Research paper thumbnail of Isotropic and Kinematic Hardening Laws: Plastic Behavior of Mild Steel Under Shear Tests

Advances in Mechanical Engineering and Mechanics II

Research paper thumbnail of Modeling of TA6V Titanium Alloy by an Identification Strategy: Biomechanical Application

Advances in Mechanical Engineering and Mechanics II

Research paper thumbnail of Mechanical behavior of materials with a compact hexagonal structure obtained by an advanced identification strategy of HCP material, AZ31B-H24

Frattura ed Integrità Strutturale

Research paper thumbnail of Identification strategy of anisotropic behavior laws: application to thin sheets of Aluminium A5

Journal of Theoretical and Applied Mechanics

Numerical simulation provides a valuable assistance in the controlling of forming processes. The ... more Numerical simulation provides a valuable assistance in the controlling of forming processes. The elasto-plastic orthotropic constitutive law is based on the choice of an equivalent stress, a hardening law and a plastic potential. An identification of the model parameters from an experimental database is developed. This database consists in hardening curves and Lankford coefficients of specimens subjected to off-axis tensile tests. The proposed identification strategy is applied to aluminum sheets. The behavior of this material is studied under several solicitations. The anisotropic behavior of the aluminum plate is modeled using the Barlat criterionand the hardening law. The obtained Lankford coefficients are compared to those which are identified by a different strategy.

Research paper thumbnail of Experimental Study on Mechanical Properties of Aluminum Alloys under Uniaxial Tensile Tests

International Journal of Technology

Research paper thumbnail of Evolution of Mechanical Behavior of Aluminum Alloy Al 7075 during Maturation Time

International Journal of Technology, 2016

The Aluminum 7075 (Al 7075) alloy is a precipitation hardening material instead of a strain harde... more The Aluminum 7075 (Al 7075) alloy is a precipitation hardening material instead of a strain hardening material. These mechanical properties are of a particular microstructure obtained by thermo-mechanical treatments. Among other things, this is a complicated microstructure which is responsible for the mechanical performance. The evolution of the mechanical properties of aluminum alloys is dependent on aging time parameters after heat treatment. In this study, the material has undergone a tempering heat treatment followed by a series of tensile tests. The experimental data (tensile curves in three directions during maturation time) is used to describe the evolution of the mechanical characteristics in terms of loading directions and maturation time, denoted respectively as: Ψ and t. The tensile curves are the source of data to begin the problem of identifying the behavior law of studied material using Barlat's model and Hollomon's isotropic hardening law. Thus, from the identified parameters (anisotropy coefficients and hardening coefficients), the evolution of the Lankford coefficient, deformation rate and load surfaces during the maturation time for three load directions (0°: rolling direction, 45° and 90°) are described. This study allows optimizing the response of the aluminum alloy to plastic strains, resulting from forming processes measured against the best time during maturation and the best load direction.

Research paper thumbnail of Identification strategy of anisotropic behavior laws: application to thin sheets of Aluminium A5

Journal of Theoretical and Applied Mechanics

Numerical simulation provides a valuable assistance in the controlling of forming processes. The ... more Numerical simulation provides a valuable assistance in the controlling of forming processes. The elasto-plastic orthotropic constitutive law is based on the choice of an equivalent stress, a hardening law and a plastic potential. An identification of the model parameters from an experimental database is developed. This database consists in hardening curves and Lankford coefficients of specimens subjected to off-axis tensile tests. The proposed identification strategy is applied to aluminum sheets. The behavior of this material is studied under several solicitations. The anisotropic behavior of the aluminum plate is modeled using the Barlat criterionand the hardening law. The obtained Lankford coefficients are compared to those which are identified by a different strategy.