Publications de Jean-Marie Drezet

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A three-dimensional (3-D) granular model which simulates fluid flow within solidifying alloys with a globular microstructure, such as that found in grain refined Al alloys, is presented. The model geometry within a representative volume element (RVE) consi ...

The biomedical industry shows increasing interest in the joining of dissimilar metals, especially with the aim of developing devices that combine different mechanical and corrosive properties. As an example, nickel titanium shape memory alloys joined to st ...

Hot tearing, a severe defect occurring during solidification is the conjunction of tensile stresses which are transmitted to the mushy zone by the coherent solid underneath and of insufficient liquid feeding to compensate for the volumetric change. The RDG ...

Epitaxial Laser Metal Forming (E-LMF) consists in impinging a jet of metallic powder onto a molten pool formed by controlled laser heating and thereby, generating epitaxially a single crystal deposit onto a single crystal substrate. It is a near net-shape process for rapid prototyping or repair engineering of single crystal high pressure/high temperature gas turbines blades. Single crystal repair using E-LMF requires controlled solidification conditions in order to prevent the nucleation and growth of cryst

A new criterion for the appearance of hot tears in metallic alloys is proposed. Based upon a mass balance performed over the liquid and solid phases, it accounts for the tensile deformation of the solid skeleton perpendicular to the growing dendrites and for the induced interdendritic liquid feeding. This model introduces a critical deformation rate beyond which cavitation, i.e. nucleation of a first void, occurs. As should be expected, this critical value is an increasing function of the thermal gradient a

Modelling represents an important tool in modern material processing which no longer follows the traditional trial and error route but rather represents what may be termed a right first time technology [1]. To successfully model technological solidification processes, thermodynamic and kinetic data are required. But mechanical aspects are important as well [2]: during solidification, temperature gradients or mechanical constraints imposed by the mold result in solidification stresses. These stresses must be

Residual stresses are investigated for the first time in a dissimilar AA1050-DP450 steel magnetic pulse weld using neutron diffraction. Close to the joint interface, tensile residual stresses are observed in the Al sheet and compressive residual stresses a ...

The tolerances of semi-continuously cast products of aluminium alloys are very critical if the scalping of the ingot faces is to be minimised before rolling. In the steady state regime of casting, the dimensions of the section of the solidified ingot are lower than those of the mould in the Direct Chill Casting (DCC) or of the inductor in the Electromagnetic Casting (EMC). The contraction of the section, several percents, is larger than the value associated with the thermal contraction of the solid and is a

The mechanical behavior of partially solidified Al-Cu alloys is investigated to assess the influence of mushy zone deformation on hot tearing. For this purpose, the results of a semi-solid tensile test conducted in situ using X-ray microtomography are comp ...

A new 3D coupled hydro-mechanical granular model that simulates hot tearing formation in metallic alloys is presented. The hydro-mechanical model consists of four separate 3D modules. (I) The Solidification Module (SM) is used for generating the initial so ...

The deformation-induced macrosegregation in continuous casting of steel has been simulated using a finite-volume scheme. For that purpose, a two-dimensional heat-flow computation was first performed in a Eulerian reference frame attached to the mold, assuming a unique solidification path, i.e., a unique relationship between temperature and enthalpy. This gave the stationary enthalpy field in the longitudinal section of the slab. On the other hand, bulging of the slab between two rolls was calculated in the

During casting of aluminum alloys, the partially solidified material is submitted to thermally induced strains that can lead to severe casting defects, such as hot tearing. In this work, carried out in the frame of the European project VIR[CAST], the rheol ...

The rigidity temperature of a solidifying alloy is the temperature at which the solid plus liquid phases are sufficiently coalesced to transmit long range tensile strains and stresses. It determines the point at which thermally induced deformations start t ...

Hydrocephalus is a cerebral disease where brain ventricles enlarge and compress the brain parenchyma towards the skull leading to symptoms like dementia, walking disorder and incontinence. The origin of normal pressure hydrocephalus is still obscure. In order to study this disease, a finite element model is built using the geometries of the ventricles and the skull measured by magnetic resonance imaging. The brain parenchyma is modelled as a porous medium fully saturated with cerebrospinal fluid (CSF) using

Inverse methods can be used in solidification and related processes for the estimation of boundary conditions or physical properties of materials. For heat flow problems, these methods are based upon a minimisation of the errors between calculated and measured temperatures at given locations and times of the space-time domain, the calculated values being obtained from a numerical solution of the heat flow equation. In the present case, a maximum a posteriori technique has been implemented into a finite elem

By means of a Gleeble machine, the flow stress at steady-state creep in an AA3103 aluminium alloy has been measured for temperatures and strain rates relevant for thermally induced deformations in DC casting. The strain rate has been determined by measuring the global radial strain rate at the specimen center by an extensometer, and the stress has been set equal to the force in the axial direction divided by the cross-section area. The parameters of Garofalo’ s equation have been fitted to the resulting ste

The rigidity temperature of a solidifying alloy is the temperature at which the solid phase is sufficiently coalesced to transmit tensile stress. It is a major input parameter in numerical modeling of solidification processes as it defines the point at whi ...

A comprehensive three-dimensional mathematical model based upon the Abaqus software has been developed for the computation of the thermomechanical state of the solidifying strand during direct chill (DC) casting of rolling sheet ingots and during subsequent cooling. Based upon a finite element formulation, the model determines the temperature distribution, the stresses and the associated deformations in the metal. For that purpose, the thermomechanical properties of the alloy have been measured up to the co

A three-dimensional (3-D) coupled hydromechanical granular model has been developed and validated to directly predict, for the first time, hot tear formation and stress strain behavior in metallic alloys during solidification. This granular model consists ...

This paper presents a 3D thermo-mechanical model of arc-welding applied to tubular K-joints susceptible to fatigue cracking. The 3D torch trajectory is reproduced to simulate both temperatures and stresses during welding and ultimately the 3D residual stress distribution after cooling. The influence of latent heat, of the increase of thermal conductivity to simulate the fluid convection within the weld pool, the activation of finite elements to simulate the use of filler wire and the number of passes on as-

Jean-Marie Drezet

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Three-dimensional granular model of semi-solid metallic alloys undergoing solidification: Fluid flow and localization of feeding

Mechanical and microstructural integrity of nickel-titanium and stainless steel laser joined wires

Application of the Rappaz-Drezet-Gremaud Hot Tearing Criterion to Welding of Aluminium Alloys

Marangoni Convection and Fragmentation in Laser Heat Treatment

A New Hot-Tearing Criterion

High Apparent Creep Activation Energies in Mushy Zone Microstructures

Investigation of residual stresses in planar dissimilar magnetic pulse welds by neutron diffraction

Direct chill and electromagnetic casting of aluminium alloys: Thermomechanical effects and solidification aspects

3-D granular modeling and in situ X-ray tomographic imaging: A comparative study of hot tearing formation and semi-solid deformation in Al-Cu alloys

A 3D coupled hydro-mechanical granular model for the prediction of hot tearing formation

Numerical simulation of deformation-induced segregation in continuous casting of steel

Rheological behavior of a commercial AA5182 aluminum alloy during solidification

In situ Neutron Diffraction during Casting: Determination of Rigidity Point in Grain Refined Al-Cu Alloys

Finite element analysis of normal pressure hydrocephalus: influence of CSF content and anisotropy in permeability

Application of Inverse Methods to the Estimation of Boundary Conditions and Properties

GLEEBLE MACHINE DETERMINATION OF CREEP LAW PARAMETERS FOR THERMALLY INDUCED DEFORMATIONS IN ALUMINIUM DC CASTING

Determination of Coherency and Rigidity Temperatures in Al-Cu Alloys Using In Situ Neutron Diffraction During Casting

Modeling of ingot distortions during direct chill casting of aluminum alloys

A 3-D coupled hydromechanical granular model for simulating the constitutive behavior of metallic alloys during solidification

Simulation of welding stresses for fatigue design of welded tubular connections