References of "Lequesne, Cédric"
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See detailExperimental and numerical study of an AlMgSc sheet formed by an incremental process
Bouffioux, Chantal ULg; Lequesne, Cédric ULg; Vanhove, H. et al

in Journal of Materials Processing Technology (2011), 211(11), 1684-1693

A recently developed AlMgSc alloy is studied since this material, which is well adapted to the aeronautic domain, is poorly known. The first objective is to reach a better knowledge of this alloy to ... [more ▼]

A recently developed AlMgSc alloy is studied since this material, which is well adapted to the aeronautic domain, is poorly known. The first objective is to reach a better knowledge of this alloy to provide the missing useful information to the aeronautic industry and to help research institutes who want to simulate sheet forming processes by Finite Element (FE) simulations. A set of experimental tests has been performed on the as-received sheets, material laws have been chosen and the corresponding material parameters have been adjusted to correctly describe the material behaviour. The second objective is to study the applicability of the Single Point Incremental Forming process (SPIF) on this material. Truncated cones with different geometries were formed and the maximum forming angle was determined. A numerical model was developed and proved to be able to predict both the force evolution during the process and the final geometrical shape. Moreover, the model helps reaching a better understanding of the process. The characterisation method described in this research and applied on the AlMgSc alloy can be extended to other alloys. In addition, the numerical simplified model, able to accurately describe the SPIF process with a reduced computation time, can be used to study more complex geometries. [less ▲]

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See detailRoller Pressure Quench Process of Steel Plate Modelling
Lequesne, Cédric ULg; Pensis, O.; Renard, M. et al

in Proceedings of Esaform 2011 (2011)

In this study, the roller pressure quench process is applied on a low-alloy steel plate with significant thickness. The aim is to obtain martensitic high strength steel without modifying the flatness. In ... [more ▼]

In this study, the roller pressure quench process is applied on a low-alloy steel plate with significant thickness. The aim is to obtain martensitic high strength steel without modifying the flatness. In order to optimize the process parameters, a finite element model is developed. The analysis couples the mechanical, thermal and metallurgical fields. This model provides results about the final microstructure, the residual stresses and the flatness at the end of the cooling process. It has been noticed that a two dimensional plane strain simulation is not accurate because it does not predict physical transversal residual stresses. A three dimensional simulation improves the results and enables to compute the thickness variation of the plate at the end of the quench process. [less ▲]

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See detailModeling of Crack Propagation in Weld Beam-to-Column Connection Submitted to Cyclic Loading with Cohesive Zone Model
Lequesne, Cédric ULg; Plumier, André ULg; Duchene, Laurent ULg et al

in Journal of ASTM International (2010), 7(5),

During the earthquakes in Japan and California in the 1990s, cracks appeared in some weld beam-to-column connections of heavy rigid frame steel buildings. This prompted the necessary assessment of the ... [more ▼]

During the earthquakes in Japan and California in the 1990s, cracks appeared in some weld beam-to-column connections of heavy rigid frame steel buildings. This prompted the necessary assessment of the performance of weld connections in terms of rotation capacity and crack propagation. In the present study, experimental tests were performed where weld connections were submitted to cyclic loadings with increasing amplitude until a macro crack event was reached. However the crack phenomenon depends on many parameters: the geometry, the material, the welding process…. For this reason, it was interesting to develop a finite element modeling of these connections in order to complete these experiments and perform a parametric study. This paper describes the finite element model development, its material parameter identification and its comparison with experimental results. The weld connections were modeled by using three-dimensional mixed solid elements. The constitutive laws applied were elastoplastic with isotropic hardening identified for the base metal and the weld metal. Crack propagation was modeled by a cohesive zone model. The parameters of this cohesive zone model were identified by an inverse method with the modeling of three point bending tests of precracked samples performed on the base and weld metals. The fatigue damage generated by the cyclic loading was computed by the fatigue continuum damage model of Lemaitre and Chaboche, which was coupled with the cohesive zone model. [less ▲]

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See detailBehavior of heavy sections welded moment connections
Plumier, André ULg; Lequesne, Cédric ULg; Degée, Hervé ULg et al

in Proceedings of the STESSA 2009 Conference (2009)

Test results on moment connections of heavy sections are presented. Flange thickness are up to 32 mm in beams and up to 97 mm in columns. Different beam to column moment ratios, shear panel design, method ... [more ▼]

Test results on moment connections of heavy sections are presented. Flange thickness are up to 32 mm in beams and up to 97 mm in columns. Different beam to column moment ratios, shear panel design, method of connecting shear tab, welding methods and consumables are considered. Fracture of the welds, cracking of the shear tab weld, ductile tearing from weld access holes and buckling of the beam flange are ob-served. Practical conclusions are derived. [less ▲]

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See detailAdaptive remeshing for incremental forming simulation
Lequesne, Cédric ULg; Henrard, Christophe ULg; Bouffioux, Chantal ULg et al

in Pavel, H. (Ed.) Proceedings of the 7th International Conference and Workshop on Numerical Simulation od 3D Sheet Metal Forming Processes (NUMISHEET 2008) (2008)

Incremental forming of aluminium sheets has been modelled by finite element simulations. However the computation time was prohibitive because the tool deforms every part of the sheet and the mesh along ... [more ▼]

Incremental forming of aluminium sheets has been modelled by finite element simulations. However the computation time was prohibitive because the tool deforms every part of the sheet and the mesh along the tool path must be very fine. Therefore, an adaptive remeshing method has been developed. The elements that are close to the tool are divided into smaller elements in order to have a fine mesh where high deformations occur. Consequently, some new nodes become inconsistent with the non-refined neighbouring elements. To overcome that problem, their displacements are constrained, i.e. dependent on their master nodes displacements. The data concerning these new nodes and elements are stored in a linked list, which is a fundamental data structure. It consists of a sequence of cells, each containing data fields and a pointer towards the next cell. The goal of this article is to explain the developments performed in the finite element code, to validate the adaptive remeshing technique and to measure its efficiency using the line test simulation. During this test, which is a simple incremental forming test, a clamped sheet is deformed by a spherical tool moving along a linear path. [less ▲]

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See detailNumerical study of the fatigue crack in welded beam-to-column connection using cohesive zone model
Lequesne, Cédric ULg; Plumier, André ULg; Degée, Hervé ULg et al

in Proceedings of the International Conference on Fracture and Damage Mechanics V (2006)

The fatigue behaviour of the welded beam-to-column connections of steel moment resisting frame in seismic area must be evaluated. The cohesive zone model is an efficient solution to study such connections ... [more ▼]

The fatigue behaviour of the welded beam-to-column connections of steel moment resisting frame in seismic area must be evaluated. The cohesive zone model is an efficient solution to study such connections by finite elements. It respects the energetic conservation and avoids numerical issues. A three-dimensional cohesive zone model element has been implemented in the home made finite element code Lagamine [1]. It is coupled with the fatigue continuum damage model of Lemaître and Chaboche [2]. The cohesive parameters are identified by the inverse method applied on a three points bending test modelling. [less ▲]

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See detailModeling of the fatigue cracks in welded beam-to-column connection of steel moment frame buildings submitted to earthquake
Lequesne, Cédric ULg; Gerday, Anne-Françoise ULg; Plumier, André ULg et al

in Aliabadi, M. H.; Planas, J.; Buchholz, F.-G. (Eds.) et al Proceedings of the 4th International Conference on Fracture and Damage Mechanics (2005)

Fatigue cracks in welded connections of steel moment frame buildings submitted to earthquakes are studied. The connections of beams with thick flanges designed to resist to seismic phenomena by plastic ... [more ▼]

Fatigue cracks in welded connections of steel moment frame buildings submitted to earthquakes are studied. The connections of beams with thick flanges designed to resist to seismic phenomena by plastic dissipation are presented. The structural components, the materials and the crack mechanics are described. To predict the crack initiation, the knowledge of residual internal stresses, generated by the welding process, is required. So these stresses are assessed by a FEM thermo-mechanical analysis. The potential sites of crack locations are detected by using an FEM model of the connection with the continuum damage model of Lemaître and Chaboche. After these FEM analyses, new meshes with specific elements located at the potential crack locations are defined. A cohesive zone law is used to model the crack propagation. This model describes the crack growth by analyzing the energy released by the generation of the new surfaces and damage micro-phenomena behind the crack tip. A constitutive tension-separation law computes this energy. In these cases of low cycle fatigue, the damage and the cyclic loading conditions are taken into account. [less ▲]

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See detailModélisation de la fissuration par fatigue des connexions poutres-colonnes de grands bâtiments en armature en acier lors de tremblements de terre
Lequesne, Cédric ULg; Plumier, André ULg; Habraken, Anne ULg

in Proceedings of the XVIIème congrès français de mécanique (CFM 2005) (2005)

Many steel frame buildings have cracked in beam-to-column connections during earthquakes. To determine the place and the moment of the crack initiation, a model of continuous damage is used in a finite ... [more ▼]

Many steel frame buildings have cracked in beam-to-column connections during earthquakes. To determine the place and the moment of the crack initiation, a model of continuous damage is used in a finite element computation. Cohesive zones model predicts the propagation. The residual stresses are evaluated before. [less ▲]

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