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1. Ship structure steel plate failure under near-field air-blast loading: Numerical simulations vs experiment

Author

Patrice Longère, André Dragon, Bruno Leblé, Anne-Gaëlle Geffroy-Grèze, Institut Clément Ader (ICA), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-IMT École nationale supérieure des Mines d'Albi-Carmaux (IMT Mines Albi), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), DCNS, Institut Pprime (PPRIME), ENSMA-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers, Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-IMT École nationale supérieure des Mines d'Albi-Carmaux (IMT Mines Albi), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), and Université de Poitiers-ENSMA-Centre National de la Recherche Scientifique (CNRS)

Subjects
Engineering, Explosive material, Constitutive equation, Structural failure, Structure (category theory), Aerospace Engineering, 020101 civil engineering, Ocean Engineering, Near and far field, 02 engineering and technology, 0201 civil engineering, law.invention, [SPI]Engineering Sciences [physics], 0203 mechanical engineering, law, Safety, Risk, Reliability and Quality, ComputingMilieux_MISCELLANEOUS, Civil and Structural Engineering, Computer simulation, business.industry, Mechanical Engineering, Structural engineering, 020303 mechanical engineering & transports, Mechanics of Materials, Automotive Engineering, Hourglass, business, Air blast
Abstract

This paper deals with the numerical simulation of the dynamic failure of a ship structure steel plate under near-field air-blast loading. Various energetic levels of air-blast loading, involving variable explosive mass and charge-plate distance, were tested leading to the bulge of the loaded plate for the lowest energy level and to the failure of the loaded plate for the highest level. A modified version of the Gurson–Tvergaard–Needleman potential was used to reproduce the response of the material along the damage-plasticity process at stake. The 3D constitutive equations were implemented as user material in the engineering finite element computation code ABAQUS ® , and numerical simulations were conducted and compared with experiments considering air-blast loaded plates. Several crucial numerical issues are addressed concerning notably the use of ABAQUS ® conwep function, the hourglass control and the influence of the model constants. Numerical results clearly show the interest of the adopted modelling for the description of salient stages of dynamic structural failure.

Published
2013

2. Experimental and numerical aspects of ship structure failure under airblast loading

Author

Bruno Leblé, Anne-Gaëlle Geffroy, Patrice Longère, Institut Clément Ader (ICA), Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-IMT École nationale supérieure des Mines d'Albi-Carmaux (IMT Mines Albi), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), DCNS Group [Lorient] (DCNS-Lorient), DCNS group, Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-IMT École nationale supérieure des Mines d'Albi-Carmaux (IMT Mines Albi), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO)

Subjects
Physics, Void (astronomy), Viscoplasticity, business.industry, QC1-999, Constitutive equation, Interaction model, Model parameters, 02 engineering and technology, Structural engineering, Strain rate, Strain hardening exponent, 021001 nanoscience & nanotechnology, 020303 mechanical engineering & transports, 0203 mechanical engineering, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], 0210 nano-technology, business, ComputingMilieux_MISCELLANEOUS, Thermal softening
Abstract

This work aims at studying experimentally and reproducing numerically the failure mechanisms of a ship structure material when submitted to severe conditions of strain and strain rate. Laboratory tests and airblast experiments were accordingly carried out and a constitutive model has been built describing the salient effects of strain hardening, thermal softening, viscoplasticity and void growth induced damage. Numerical simulations were conducted considering plates subjected to various airblast loading conditions. The numerical results show clearly the influence of the damage and further fracture related model parameters, as well as the limitation of the fluid/structure interaction model used in the present work.

Published
2012

3. Modeling the Transition between Dense Metal and Damaged (Microporous) Metal Viscoplasticity

Author

Anne-Gaëlle Geffroy, Bruno Leblé, André Dragon, Patrice Longère, Institut Clément Ader (ICA), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-IMT École nationale supérieure des Mines d'Albi-Carmaux (IMT Mines Albi), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), DCNS, Institut Pprime (PPRIME), ENSMA-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers, Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-IMT École nationale supérieure des Mines d'Albi-Carmaux (IMT Mines Albi), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), and Université de Poitiers-ENSMA-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Viscoplasticity, Mechanical Engineering, Constitutive equation, Computational Mechanics, 02 engineering and technology, Microporous material, Plasticity, 021001 nanoscience & nanotechnology, Metal, [SPI]Engineering Sciences [physics], 020303 mechanical engineering & transports, 0203 mechanical engineering, Mechanics of Materials, visual_art, visual_art.visual_art_medium, General Materials Science, Composite material, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract

This article presents a physically motivated approach, which has been developed in order to describe the transition of behavior between dense metal plasticity and microporous metal plasticity in the context of dynamic plasticity and adiabatic conditions. Considering that void germination requires a certain amount of plastic deformation, a ‘primary’ hole nucleation criterion as well as a statistical law governing the ‘secondary’ hole formation kinetics has been proposed. In a consistent way, the hole nucleation criterion accounts for the accelerating effects of stress triaxiality and the delaying effects of temperature and strain rate. In addition, a modification of the GTN model was proposed, allowing for describing cavity growth under shear loading. The 3D constitutive equations were implemented as user material in the engineering finite element computation code Abaqus®. Numerical simulations were conducted considering a single finite element under uniaxial tensile loading and simple shear then notched cylindrical samples under remote uniaxial tensile loading. The numerical results clearly show the influence of the hole nucleation criteria on the ductile damage and failure.

Published
2011

4. Fracture analysis and constitutive modelling of ship structure steel behaviour regarding explosion

Author

Anne-Gaëlle Geffroy, Patrice Longère, Bruno Leblé, Institut Clément Ader (ICA), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-IMT École nationale supérieure des Mines d'Albi-Carmaux (IMT Mines Albi), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), Laboratoire d'Ingénierie des Matériaux de Bretagne (LIMATB), Université de Bretagne Sud (UBS)-Institut Brestois du Numérique et des Mathématiques (IBNM), Université de Brest (UBO)-Université de Brest (UBO)-Université de Brest (UBO), DCNS, Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-IMT École nationale supérieure des Mines d'Albi-Carmaux (IMT Mines Albi), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Brestois du Numérique et des Mathématiques (IBNM), and Université de Brest (UBO)-Université de Brest (UBO)

Subjects
Structural material, Materials science, General Engineering, 02 engineering and technology, Strain rate, 021001 nanoscience & nanotechnology, Finite element method, Cracking, [SPI]Engineering Sciences [physics], 020303 mechanical engineering & transports, 0203 mechanical engineering, Hardening (metallurgy), Ultimate failure, General Materials Science, Composite material, Pearlite, 0210 nano-technology, Underwater explosion, ComputingMilieux_MISCELLANEOUS
Abstract

Consistent constitutive modelling of material behaviour and further reliable numerical prediction of the response of structures under severe loading necessitate the knowledge of the microstructural mechanisms at the origin of failure. The present work deals notably with the identification of the microstructural damage mechanisms of a high purity (ferritic–pearlitic) mild steel employed as structural material in military ship building. With this aim in view, an extensive campaign of experiments has been carried out, including interrupted and until fracture tests on smooth and notched, axisymmetric and plane specimens. Initial and post-mortem microstructures of the samples have been observed using a scanning electron microscope (SEM) in order to reveal the damage mechanism. The latter is double: quasi spherical cavity nucleation and growth inside the soft ferritic matrix and microcracking at the (soft)ferrite–(hard)pearlite interphase. Conditions for initiation and evolution of these two kinds of damage appear as being different as expected. The various steps of diffuse damage, microcracking and macro cracking yielding ultimate failure are also observed. Fractographies obtained from tensile tested samples and explosion loaded plates are also compared. Moreover, the material behaviour has been modelled, describing the salient effects observed experimentally, namely strain and strain rate hardening, and thermal and damage softening. The parameters identification was accomplished using an inverse method based methodology. Finite element numerical simulations involving far-field underwater explosion loading implemented as user subroutine in the FE computation code ABAQUS has also been performed, leading to a satisfying agreement between experimental and numerical results.

Published
2011

5. Les DRMs : entre protection légale et protection technique des biens culturels à l'ère numérique

Author

Anne-Gaëlle Geffroy

Subjects
jel:L88, jel:L86, ComputingMilieux_LEGALASPECTSOFCOMPUTING, jel:L51, jel:L63, General Economics, Econometrics and Finance
Abstract

The protection offered by the exclusive copyright is based on two distinct and complementary pillars: legal protection and technical protection through private measures. Copyright law in the digital environment has modified the balance of this system by putting in place a legal protection of the technical measures of protection. What is the economic rationale behind this modification? What are the consequences on the organization of cultural industries? The article addresses these two questions. JEL code – L51, L63, L86, L88, 034.

Published
2006

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