Today, peen forming is performed through a step by step peening operation with partial coverage a... more Today, peen forming is performed through a step by step peening operation with partial coverage and partial automation. It requires time, experience, controls and correction operations. There is definitely a need for automatic manufacturing of large shaped components such as: wing skin, spar, wing panels... By coupling the existing knowledge of experts, numerical results, and experimental data, with special automatic learning and optimization techniques, CADLM thanks to its Advanced Intelligent Design of Structures System can provides a solution for a fully automatic peen forming process where instructions given to the robot would directly lead to the final required shape. The paper first reports experimental works with ceramic beads on material to built a data base of elementary cases to allow capitalising results and generating rules. Different parameters have been studied such as bead size and velocity and panel thickness. Then reverse problem has been studied: bigger flat panels...
<jats:title>Abstract</jats:title> <jats:p>By the coupling of the existing knowl... more <jats:title>Abstract</jats:title> <jats:p>By the coupling of the existing knowledge of experts, the numerical results and the experimental data with the help of some special automatic learning and optimization techniques, it is now possible to propose a very simple tool to design materials. The purpose of this paper is to show its particular application to the very difficult design of woven composites where it is necessary to adjust the mechanical properties, the electromagnetic properties and taking care of the price too.</jats:p>
<jats:title>Abstract</jats:title> <jats:p>We consider the optimal design of a b... more <jats:title>Abstract</jats:title> <jats:p>We consider the optimal design of a beam. To improve the safety of a car during the crash, it is needed to dissipate the maximum of energy within a limited displacement but with a limited acceleration at the level of the driver/passengers. The beam may have different complex cells linked with continuous or spot solders. In a special office, they have to design a beam. In Germany, in United Kingdom, and also inside all the automotive industries, dedicated centers to test such beams were created. Other centers have developped numerical simulations. Usually, for each family of beams, a Design of Experiments is performed.</jats:p> <jats:p>It is necessary to find its optimal design. Until now, this was not possible, as the CRASH is a very complex problem and the tests or numerical simulations are too expensive to allow the succssive iterations.</jats:p>
<jats:title>Abstract</jats:title> <jats:p>During inelastic analysis, actually, ... more <jats:title>Abstract</jats:title> <jats:p>During inelastic analysis, actually, only estimations of the errors are made what is not sufficient. Very often, even if these estimators are very small, this does not imply that the errors i.e. the difference between the exact solution of any field (stress, strain, energy ...) and the approximated solution of the field obtained with the numerical simulation, is small!</jats:p> <jats:p>Sometimes, Engineers will perform the numerical simulations, then they will reduce the mesh according some rules, and if the new solution is not too far from the previous one, they will take it as a good one. This is very expensive and this is not efficient. Indeed, a lot of expertise is needed during the numerical simulations with also experimental correlations.</jats:p> <jats:p>It is practically important to have a method where, when the range of the error (that will never be known in principle) is required, it is possible to indicate a priori the minimum cost (or Number of Degrees of Freedom or number of nodes) and to draw the optimal mesh (i.e. with this minimal number) to reach this error.</jats:p> <jats:p>We shown, with automatic learning, that it is possible to extract some useful rules.</jats:p> <jats:p>The main difficulty is that only a few examples of EXACT INELASTIC SOLUTIONS are known (cylinder, sphere with symmetrical loadings!) and in order to perform any automatic learning, it is necessary to have a data base of representative examples which contains several elastoplastic structures, their discretizations and for each of them the known errors!!</jats:p>
The engineers have to face very important problems in the design, the test, the survey and the ma... more The engineers have to face very important problems in the design, the test, the survey and the maintenance of their structures. These problems did not yet get full answer even from the best people in the world. Usually in these problems (such as no satisfactory constitutive modeling of materials, no real control of the accuracy of the numerical simulations, no real definition of the initial state and/or the effective loading of the structure), there is no solution and the experts do not understand the problem in its whole. Moreover, the available data may be not statistically representative (i.e. are in limited number), fuzzy, qualitative and missing in part. We propose a practical solution the «Intelligent Optimal Design of Materials and Structures» where the actual best knowledges of the researchers/experts are intelligently mixed to the results of experiments or real returns. Several examples of applications are given in this serial set of papers to explain the real meaning and p...
The engineers have to face very important problems in the design, the test, the survey and the ma... more The engineers have to face very important problems in the design, the test, the survey and the maintenance of their structures. These problems did not yet get full answer even from the best people in the world. Usually in these problems (such as no satisfactory constitutive modeling of materials, no real control of the accuracy of the numerical simulations, no real definition of the initial state and/or the effective loading of the structure), there is no solution and the experts do not understand the problem in its whole. Moreover, the available data may be not statistically representative (i.e. are in limited number), fuzzy, qualitative and missing in part. We propose a practical solution the «Intelligent Optimal Design of Materials and Structures» where the actual best knowledges of the researchers/experts are intelligently mixed to the results of experiments or real returns.
Our objective in this paper is to show how to reach a real physical approach of the multiaxial ra... more Our objective in this paper is to show how to reach a real physical approach of the multiaxial random loadings which is very easy to perform and which allows the optimal reliability of a structure. The main idea of the approach is to find an Equivalence rule between two complex loadings relative to "Damage" which may be used as a "Quantification" or norm of any loading relative to one particular material. This rule must have the physical meaning of "damage" and allows for the construction of simple and practical cyclic radial loadings and tools for fatigue analysis or accelerated fatigue tests. A new framework for fatigue analysis and reliability of structures has been built which, based on a multi-scale analysis, allows the analyis to be reduced to the analysis on a 2-D window with a Characterized radial cyclic loading. Here, it is given one description for the smooth specimen and any general structure with any loading conditions. Simplified analysis o...
Large Deformations of Solids: Physical Basis and Mathematical Modelling, 1987
Session I: General Concepts.- 1. Sur Quelques Concepts Fondamentaux de la Mecanique.- 2. The Stat... more Session I: General Concepts.- 1. Sur Quelques Concepts Fondamentaux de la Mecanique.- 2. The Statistical Basis of Polycrystal Plasticity.- 3. Modelling of Finite Deformations of Anisotropic Materials.- 4. Microlocal Aspects of Finite Deformations in the Light of Nonstandard Analysis.- Session II: Metals-Physical Point of View.- 5. Deformations Finies des Agregats Metaux: Aspects Physiques et Metallurgiques.- 6. The Effect of Partial Reversibility of Dislocation Motion.- 7. Effective-cluster Simulation of Polycrystal Plasticity.- 8. Pseudoelasticity and Shape Memory.- 9. A Unified Elastic-Viscoplastic Theory with Large Deformations.- Session III: Metals-Continuum Point of View.- 10. Interaction between Physical Mechanisms and the Structure of Continuum Theories.- 11. Microstructure and Phenomenological Models for Metals.- 12. Study of the Constitutive Law for a Polycrystal and Analysis of Rate Boundary Value Problem in Finite Elastoplasticity.- 13. Thermodynamique et Viscoplasticite du Monocristal Metallique: Comparaison et Synthese de Modeles a Variables Internes.- 14. Some Applications of the Self-consistent Scheme in the Field of Plasticity and Texture of Metallic Polycrystals.- 15. Fundamental Considerations in Micromechanical Modeling of Polycrystalline Metals at Finite Strain.- Session IV: Rocks and Composites.- 16. Generalization of the Mandel-Spencer Double-Slip Model.- 17. On the Structure of Single Slip and its Implications for Inelasticity.- 18. Kinematics in Plastically Deformed Rocks.- 19. A Theory for Coupled Stress and Fluid Flow Analysis in Jointed Rock Masses.- Session V: Soils.- 20. L'Effet de la Formation des Surfaces de Glissement dans les Milieux Continus.- 21. On Large Deformations of Rock-type Transversely Isotropic Materials.- 22. Physical Bases for the Thermo-Hygro-Rheological Behaviours of Wood in Finite Deformations.- 23. Bifurcation par Localisation de la Deformation: Etude Experimentale et Theorique a L'Essai Biaxial sur Sable.- 24. A Mechanical Description of Saturated Soils.- 25. Some Macroscopic Consequences of the Granular Structure of Sand.
Some numerical analyses of elastoplastic structures requires enormous computational efforts when ... more Some numerical analyses of elastoplastic structures requires enormous computational efforts when dealing with classical methods.
The scientific work of Jean Mandel has been exceptionally rich in the area of the mechanics of so... more The scientific work of Jean Mandel has been exceptionally rich in the area of the mechanics of solids; the subjects which he has treated have been extremely diverse, from the theory of plasticity, buckling, soil mechanics, visco-elasticity, the theory of reduced models, and thermo dynamics, to percolation in porous media. But throughout this com prehensive work Jean Mandel has always maintained his interest in forming connections between the properties of materials (strength, deformability, viscosity) and the properties of their basic constituents. What is sometimes referred to in materials science as the transition from the microscopic to the macroscopic has for him been a very constant direction of research, which he never ceased to encourage in the Laboratoire de Mecanique des Solides of which he was the director. It is known that in the plasticity of metals permanent deformations must be sought in intercrystalline slip and more generally in disloca tions and the various microstr...
... Titre du document / Document title. Optimal design of woven composite materials. Auteur(s) / ... more ... Titre du document / Document title. Optimal design of woven composite materials. Auteur(s) / Author(s). ZARKA J. (1) ; DOUX T. (2) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). (1) Laboratoire de Mécanique des Solides ...
International Journal of Solids and Structures, 1977
... Printed in Girat Briuin ELASTIC CONTACT BETWEEN A SPHERE AND A SEMI INFINITE TRANSVERSELY ISO... more ... Printed in Girat Briuin ELASTIC CONTACT BETWEEN A SPHERE AND A SEMI INFINITE TRANSVERSELY ISOTROPIC BODY MARC DAHAN and JOSEPH ZARKA Laboratoire de M ... po/sinaf cosaA Cs,(ds,lc)+Ds^ds^-c)=^^-J^-}, C(a's,^-l)+D(a's-^l-)=0. F_ po/smat cosaA pi ...
Today, peen forming is performed through a step by step peening operation with partial coverage a... more Today, peen forming is performed through a step by step peening operation with partial coverage and partial automation. It requires time, experience, controls and correction operations. There is definitely a need for automatic manufacturing of large shaped components such as: wing skin, spar, wing panels... By coupling the existing knowledge of experts, numerical results, and experimental data, with special automatic learning and optimization techniques, CADLM thanks to its Advanced Intelligent Design of Structures System can provides a solution for a fully automatic peen forming process where instructions given to the robot would directly lead to the final required shape. The paper first reports experimental works with ceramic beads on material to built a data base of elementary cases to allow capitalising results and generating rules. Different parameters have been studied such as bead size and velocity and panel thickness. Then reverse problem has been studied: bigger flat panels...
<jats:title>Abstract</jats:title> <jats:p>By the coupling of the existing knowl... more <jats:title>Abstract</jats:title> <jats:p>By the coupling of the existing knowledge of experts, the numerical results and the experimental data with the help of some special automatic learning and optimization techniques, it is now possible to propose a very simple tool to design materials. The purpose of this paper is to show its particular application to the very difficult design of woven composites where it is necessary to adjust the mechanical properties, the electromagnetic properties and taking care of the price too.</jats:p>
<jats:title>Abstract</jats:title> <jats:p>We consider the optimal design of a b... more <jats:title>Abstract</jats:title> <jats:p>We consider the optimal design of a beam. To improve the safety of a car during the crash, it is needed to dissipate the maximum of energy within a limited displacement but with a limited acceleration at the level of the driver/passengers. The beam may have different complex cells linked with continuous or spot solders. In a special office, they have to design a beam. In Germany, in United Kingdom, and also inside all the automotive industries, dedicated centers to test such beams were created. Other centers have developped numerical simulations. Usually, for each family of beams, a Design of Experiments is performed.</jats:p> <jats:p>It is necessary to find its optimal design. Until now, this was not possible, as the CRASH is a very complex problem and the tests or numerical simulations are too expensive to allow the succssive iterations.</jats:p>
<jats:title>Abstract</jats:title> <jats:p>During inelastic analysis, actually, ... more <jats:title>Abstract</jats:title> <jats:p>During inelastic analysis, actually, only estimations of the errors are made what is not sufficient. Very often, even if these estimators are very small, this does not imply that the errors i.e. the difference between the exact solution of any field (stress, strain, energy ...) and the approximated solution of the field obtained with the numerical simulation, is small!</jats:p> <jats:p>Sometimes, Engineers will perform the numerical simulations, then they will reduce the mesh according some rules, and if the new solution is not too far from the previous one, they will take it as a good one. This is very expensive and this is not efficient. Indeed, a lot of expertise is needed during the numerical simulations with also experimental correlations.</jats:p> <jats:p>It is practically important to have a method where, when the range of the error (that will never be known in principle) is required, it is possible to indicate a priori the minimum cost (or Number of Degrees of Freedom or number of nodes) and to draw the optimal mesh (i.e. with this minimal number) to reach this error.</jats:p> <jats:p>We shown, with automatic learning, that it is possible to extract some useful rules.</jats:p> <jats:p>The main difficulty is that only a few examples of EXACT INELASTIC SOLUTIONS are known (cylinder, sphere with symmetrical loadings!) and in order to perform any automatic learning, it is necessary to have a data base of representative examples which contains several elastoplastic structures, their discretizations and for each of them the known errors!!</jats:p>
The engineers have to face very important problems in the design, the test, the survey and the ma... more The engineers have to face very important problems in the design, the test, the survey and the maintenance of their structures. These problems did not yet get full answer even from the best people in the world. Usually in these problems (such as no satisfactory constitutive modeling of materials, no real control of the accuracy of the numerical simulations, no real definition of the initial state and/or the effective loading of the structure), there is no solution and the experts do not understand the problem in its whole. Moreover, the available data may be not statistically representative (i.e. are in limited number), fuzzy, qualitative and missing in part. We propose a practical solution the «Intelligent Optimal Design of Materials and Structures» where the actual best knowledges of the researchers/experts are intelligently mixed to the results of experiments or real returns. Several examples of applications are given in this serial set of papers to explain the real meaning and p...
The engineers have to face very important problems in the design, the test, the survey and the ma... more The engineers have to face very important problems in the design, the test, the survey and the maintenance of their structures. These problems did not yet get full answer even from the best people in the world. Usually in these problems (such as no satisfactory constitutive modeling of materials, no real control of the accuracy of the numerical simulations, no real definition of the initial state and/or the effective loading of the structure), there is no solution and the experts do not understand the problem in its whole. Moreover, the available data may be not statistically representative (i.e. are in limited number), fuzzy, qualitative and missing in part. We propose a practical solution the «Intelligent Optimal Design of Materials and Structures» where the actual best knowledges of the researchers/experts are intelligently mixed to the results of experiments or real returns.
Our objective in this paper is to show how to reach a real physical approach of the multiaxial ra... more Our objective in this paper is to show how to reach a real physical approach of the multiaxial random loadings which is very easy to perform and which allows the optimal reliability of a structure. The main idea of the approach is to find an Equivalence rule between two complex loadings relative to "Damage" which may be used as a "Quantification" or norm of any loading relative to one particular material. This rule must have the physical meaning of "damage" and allows for the construction of simple and practical cyclic radial loadings and tools for fatigue analysis or accelerated fatigue tests. A new framework for fatigue analysis and reliability of structures has been built which, based on a multi-scale analysis, allows the analyis to be reduced to the analysis on a 2-D window with a Characterized radial cyclic loading. Here, it is given one description for the smooth specimen and any general structure with any loading conditions. Simplified analysis o...
Large Deformations of Solids: Physical Basis and Mathematical Modelling, 1987
Session I: General Concepts.- 1. Sur Quelques Concepts Fondamentaux de la Mecanique.- 2. The Stat... more Session I: General Concepts.- 1. Sur Quelques Concepts Fondamentaux de la Mecanique.- 2. The Statistical Basis of Polycrystal Plasticity.- 3. Modelling of Finite Deformations of Anisotropic Materials.- 4. Microlocal Aspects of Finite Deformations in the Light of Nonstandard Analysis.- Session II: Metals-Physical Point of View.- 5. Deformations Finies des Agregats Metaux: Aspects Physiques et Metallurgiques.- 6. The Effect of Partial Reversibility of Dislocation Motion.- 7. Effective-cluster Simulation of Polycrystal Plasticity.- 8. Pseudoelasticity and Shape Memory.- 9. A Unified Elastic-Viscoplastic Theory with Large Deformations.- Session III: Metals-Continuum Point of View.- 10. Interaction between Physical Mechanisms and the Structure of Continuum Theories.- 11. Microstructure and Phenomenological Models for Metals.- 12. Study of the Constitutive Law for a Polycrystal and Analysis of Rate Boundary Value Problem in Finite Elastoplasticity.- 13. Thermodynamique et Viscoplasticite du Monocristal Metallique: Comparaison et Synthese de Modeles a Variables Internes.- 14. Some Applications of the Self-consistent Scheme in the Field of Plasticity and Texture of Metallic Polycrystals.- 15. Fundamental Considerations in Micromechanical Modeling of Polycrystalline Metals at Finite Strain.- Session IV: Rocks and Composites.- 16. Generalization of the Mandel-Spencer Double-Slip Model.- 17. On the Structure of Single Slip and its Implications for Inelasticity.- 18. Kinematics in Plastically Deformed Rocks.- 19. A Theory for Coupled Stress and Fluid Flow Analysis in Jointed Rock Masses.- Session V: Soils.- 20. L'Effet de la Formation des Surfaces de Glissement dans les Milieux Continus.- 21. On Large Deformations of Rock-type Transversely Isotropic Materials.- 22. Physical Bases for the Thermo-Hygro-Rheological Behaviours of Wood in Finite Deformations.- 23. Bifurcation par Localisation de la Deformation: Etude Experimentale et Theorique a L'Essai Biaxial sur Sable.- 24. A Mechanical Description of Saturated Soils.- 25. Some Macroscopic Consequences of the Granular Structure of Sand.
Some numerical analyses of elastoplastic structures requires enormous computational efforts when ... more Some numerical analyses of elastoplastic structures requires enormous computational efforts when dealing with classical methods.
The scientific work of Jean Mandel has been exceptionally rich in the area of the mechanics of so... more The scientific work of Jean Mandel has been exceptionally rich in the area of the mechanics of solids; the subjects which he has treated have been extremely diverse, from the theory of plasticity, buckling, soil mechanics, visco-elasticity, the theory of reduced models, and thermo dynamics, to percolation in porous media. But throughout this com prehensive work Jean Mandel has always maintained his interest in forming connections between the properties of materials (strength, deformability, viscosity) and the properties of their basic constituents. What is sometimes referred to in materials science as the transition from the microscopic to the macroscopic has for him been a very constant direction of research, which he never ceased to encourage in the Laboratoire de Mecanique des Solides of which he was the director. It is known that in the plasticity of metals permanent deformations must be sought in intercrystalline slip and more generally in disloca tions and the various microstr...
... Titre du document / Document title. Optimal design of woven composite materials. Auteur(s) / ... more ... Titre du document / Document title. Optimal design of woven composite materials. Auteur(s) / Author(s). ZARKA J. (1) ; DOUX T. (2) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). (1) Laboratoire de Mécanique des Solides ...
International Journal of Solids and Structures, 1977
... Printed in Girat Briuin ELASTIC CONTACT BETWEEN A SPHERE AND A SEMI INFINITE TRANSVERSELY ISO... more ... Printed in Girat Briuin ELASTIC CONTACT BETWEEN A SPHERE AND A SEMI INFINITE TRANSVERSELY ISOTROPIC BODY MARC DAHAN and JOSEPH ZARKA Laboratoire de M ... po/sinaf cosaA Cs,(ds,lc)+Ds^ds^-c)=^^-J^-}, C(a's,^-l)+D(a's-^l-)=0. F_ po/smat cosaA pi ...
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