E. Massoni - Academia.edu (original) (raw)

Papers by E. Massoni

This paper deals with the use of mixte 3D F.E. to simulate heat treatment processes. A complete t... more This paper deals with the use of mixte 3D F.E. to simulate heat treatment processes. A complete thermo-elasto-visco-plastic THEVP constitutive equation is chosen to cover a large domain of deformation (Colonna et al.), from purely viscoplastic at high temperature to elastic at the end of the heat treatment process, with non linear kinematic/isotropic hardening laws. A 3D mixte finite element (velocity/pressure) is used with the same interpolation for mechanical and thermal discretisation. This formulation is based on the mini-element formulation for linear and non linear cases, with stabilized element in order to satisfy the compatibility conditions (Arnold et al.).

AIP Conference Proceedings, 2004

Hemming is a mechanical joining method that is typically used to connect two sheet metal componen... more Hemming is a mechanical joining method that is typically used to connect two sheet metal components, such as inner and outer panels of automobile doors or hoods. Hemming generates defects like outer sheet size reduction (called roll-in), cracks and sheet metal springback. This affects the final dimensions of the hemmed part and can cause problems in the assembly stage or

Computer Methods in Applied Mechanics and Engineering, 2016

We propose in this work an adaptive variational multiscale method for two-fluid flows with surfac... more We propose in this work an adaptive variational multiscale method for two-fluid flows with surface tension. A level set function is used to provide a precise position of the interfaces. The implementation of the surface tension in the context of the Continuum Surface Force is proposed to circumvent the capillary time step restriction. The obtained system is then solved using a new derived Variational Multiscale stabilized finite element method designed to handle the abrupt changes at the interface and large density and viscosity ratios. Combined with an a posteriori error estimator, we show that anisotropic mesh adaptation provides highly stretched elements at the interfaces and thus yield an accurate modeling framework for two-phase incompressible isothermal flows. Stable and accurate results are obtained for all two-and three-dimensional numerical examples. To the best of our knowledge, these are the first simulation results for representative time-dependent three-dimensional two-fluid flow problems using an implicit treatment of the surface tension and a dynamic unstructured anisotropic mesh adaptation.

A mathematical and numerical model to design an industrial software solution able to handle real ... more A mathematical and numerical model to design an industrial software solution able to handle real complex furnaces con gurations in terms of geometries, atmospheres, parts positioning, heat generators and physical thermal phenomena has been developed. A three dimensional algorithm based on stabilized nite element methods (SFEM) for solving the momentum [1], energy, turbulence and radiation equations is presented. An immersed volume method for thermal coupling of fuids and solids is introduced. It consists in considering a single 3D grid of the furnace and solving one set of equations for both uid and solid with di erent thermal properties which can reduce the computational costs. A level set function enables to de ne precisely the position and the interface of any objects inside the furnace and to provide homogeneous physical and thermodynamic properties for each subdomain. Furthermore, in order to ensure an accurate capture of the discontinuities that characterize the strongly heterogeneous domain, we resort to an anisotropic mesh adaptation algorithm based on the variations of the level set function. The proposed method demonstrates the capability of the model to simulate an unsteady three dimensional heat transfers and turbulent fows in an industrial furnace with the presence of conducting solids

Key Engineering Materials, 2014

The design of processes like magnetic pulse forming and electrohydraulic forming involves multiph... more The design of processes like magnetic pulse forming and electrohydraulic forming involves multiphysical couplings that require numerical simulation, and knowledge on dynamic behaviour of metals. The forming process is completed in about 100 μs, so that the workpiece material deforms at strain-rates between 100 and 10 000 s-1. In this range, the mechanical behaviour can be significantly different than that in quasi-static conditions. It is often noticed that the strength and the formability are higher. The main goal of this study is to use an electromagnetically driven test on tubes or sheets to identify the constitutive behaviour of the workpiece material. In the case of tube, an industrial helix coil is used as inductor. Simulations with the code LS-Dyna® permit to find a configuration where the tube deforms homogeneously enough to allow axisymmetric modelling of the setup. The coil current is measured and used as an input for the simulations. The radial expansion velocity is measu...

Advanced Technology of Plasticity 1987, 1987

Engineering Computations, 1995

A complete thermo‐mechanical model for the simulation of the inertia welding process of two simil... more A complete thermo‐mechanical model for the simulation of the inertia welding process of two similar parts is described. The material behaviour is represented by an incompressible viscoplastic Norton—Hoff law in which the rheological parameters are dependent on temperature. The friction law was determined experimentally and depends on the prescribed pressure and the relative rotating velocity between the two parts. The mechanical problem is solved considering the virtual work principle including inertia terms. The computation of the three components of the velocity field such as radial, longitudinal and rotational velocity, in an axisymmetric approximation allows to take into account the torsional effects. The domain is updated based on a Lagrangian formulation. The non‐linear heat transfer equation with boundary conditions (convection, radiation and friction flux) is solved separately for each time step. Error estimators on mechanical and thermal computation are devised to adapt the...

Journal of Materials Processing Technology, 2002

Forming process simulations require a precise knowledge of the input material parameters. These p... more Forming process simulations require a precise knowledge of the input material parameters. These parameters are usually estimated from mechanical tests. The classical analysis of these tests are usually based on a few assumptions: material flow homogeneity, isothermal conditions, etc. But in some cases with strain localisation or self-heating, these assumptions overestimate material strength. Analysis techniques using inverse methods are then good alternatives. This paper deals with the estimation of mechanical parameters using an inverse method. The direct model is a 3D forming process simulation software (FORGE3®). The numerical formulation is based on a mixed finite element method using two unknowns, the velocity and the pressure. The tetrahedron element is linear in velocity and pressure and the thermal problem is solved using a linear element. The inverse problem associated with the estimation of mechanical parameters is expressed as a least square problem. The aim is to obtain output of the direct model which fits experimental data measured during the mechanical test. The optimisation problem is solved using a Gauss–Newton algorithm. At the end of the optimisation, an estimation of confidence intervals is done. A Gauss–Newton algorithm requires the computation of the derivatives of the output with respect to the parameters to be identified. In this work, a semi-analytical differentiation is performed. The proposed method is first validated on artificial experimental data obtained from direct simulations of hot uniaxial compressions for a viscoplastic cylinder. The confidence interval is provided by the algorithm for different configurations with additional random noise. Finally a real steel compression test is analysed to provide parameters for the Norton–Hoff viscoplastic law.

Journal of Materials Processing Technology, 1992

... a CEMEF-Ecole des Mines de Paris-Sophia Antipolis, 06560 Valbonne, France. b Engineering Syst... more ... a CEMEF-Ecole des Mines de Paris-Sophia Antipolis, 06560 Valbonne, France. b Engineering System International, 20 rue Saarinen, Silic 270, 94578 Rungis-cédex, France. Available online 27 February 2003. Abstract. ... 10 Di. Pasquale, E. El:Khaldi, F. Haug, E. Aita, Proc. ...

Computer Methods in Applied Mechanics and Engineering, 1993

... EquWlent alf (MPa) Inonmnt no ; 1 RC V0N.DON 1 1 q16.00 gq E0.00 0 q E6.00 4 Mju 00.00 6 Q&am... more ... EquWlent alf (MPa) Inonmnt no ; 1 RC V0N.DON 1 1 q16.00 gq E0.00 0 q E6.00 4 Mju 00.00 6 Q&quot; x,00 e . 40.00 Men1* .4413E*02 Minl .482E08 Fut, my&quot;. ... [13] H. Gegel, Synthesis of atomistics and continuum modeling to describe microstructure, in: RJ Arsenault, JR Belles, Jr. ...

Les Cahiers de% heotogie, 1996

... et à identifier les nouveaux paramètres correspondants en utilisant la procédure automatique ... more ... et à identifier les nouveaux paramètres correspondants en utilisant la procédure automatique développée. ... différentes lois de comportement (avec au moins 6-8 paramètres testés jusqu&amp;#x27;à ... [13] GAVRUS A., MASSONI E., CHENOT JL,&amp;quot; Constitutive parameter identification using a ...

-Les composants pour la liaison au sol sont classiquement dimensionnés à la fatigue polycyclique.... more -Les composants pour la liaison au sol sont classiquement dimensionnés à la fatigue polycyclique. Le comportement du matériau est donc très simple à prédire car élastique. Néanmoins, la connaissance du comportement plastique ne peut être écartée pour deux raisons principales : tout d'abord, les pièces de liaison au sol sont mises en forme par déformation plastique (emboutissage), opération générant des états mécaniques locaux complexes qu'il est nécessaire de prendre en compte dans les étapes de dimensionnement ultérieures ; ensuite car le dimensionnement doit permettre d'assurer l'intégrité du composant lorsque celui-ci est soumis à des coups forts, pouvant générer localement de la plasticité. Dans ce contexte, les travaux exposés ici portent sur deux points. Dans un premier temps, nous nous sommes intéressés à l'identification de modèles élastoplastiques (isotrope, cinématique et mixte [3]) réalisée sur une base expérimentale constituée d'essais de pliage/dépliage sur tôle. Une attention toute particulière est portée à la compétition entre écrouissage cinématique et isotrope. Les essais sont réalisés sur un dispositif de flexion pure développé au CEMEF. L'identification est permise par un algorithme spécifique d'identification présenté en figure 2-b. Dans un second temps, les modèles identifiés sont testés sur une base expérimentale enrichie combinant des essais de pliage/dépliage cyclique à des mesures de contraintes résiduelles après relâchement. Un indicateur d'erreur est mis en place afin de hiérarchiser les capacités de prédiction des modèles. Celui-ci nous permet de conclure à la supériorité du modèle mixte. Keywords-modèles de comportement élastoplastique, mise en forme de tôle, prédiction de contraintes résiduelles.

Journal of Engineering Materials and Technology, 2003

In this paper, a constitutive equation for superplasticity, which is based on the microstructural... more In this paper, a constitutive equation for superplasticity, which is based on the microstructural mechanism of superplastic deformation taking into account the effects of deformation damage, is incorporated into the finite element method to simulate the superplastic forming process. The effects of strain rate sensitivity, cavity growth and imposed hydrostatic pressure on the strain limit are studied. The predicted results are validated through the comparison with the existing experimental data. It is found that the present model produces accurate results in all cases.

ABSTRACT Numerical modeling of processes and experimental measurements now make it possible to op... more ABSTRACT Numerical modeling of processes and experimental measurements now make it possible to optimise the sheet forming parameters. In this paper, two criteria for the detection of localised necking during stamping of sheets are introduced and used for orthotropic and Barlat's anisotropic laws. The first approach uses perturbation techniques to calculate how the stability of the local mechanical equilibrium can be violated locally. The second criterion is based on the study of diffuse necking. It assumes that the material in the localisation band tends to a plane strain deformation mode and the maximum force for this local configuration is calculated. Both criteria are used with 3D finite element analysis of Nakazima and cross die stamping tests. Numerical predictions are compared to experimental results. A 3D strain measurement system based on correlation of images is used to determine the strain field on sheets, specifically in the area of localisation or fracture.

The thermal analysis using standard linear tetrahedral finite elements may be affected by spuriou... more The thermal analysis using standard linear tetrahedral finite elements may be affected by spurious local extrema in the regions affected by thermal shocks, in such a severe way to discourage the use of these elements. The present work proposes a mixed continuous temperature/heat flux formulation to solve the unsteady thermal problem. This new numerical model should allow to improve the thermomechanical coupling effects during the simulation of 3D forming processes (for example during hot or cold forging processes and during heat treatment. The spatial model is based on the Galerkin approach with the linear tetrahedral P1/P1 mixed finite elements. Time integration is based on an implicit scheme. The performance of this method is evaluated by means of test case with analytical solution, as well as an industrial application, for which a well-behaved numerical solution is available, and by comparisons with two discontinuous Galerkin : the explicit Taylor Discontinuous Galerkin scheme, DTG (P0/P0 interpolation and third degree Taylor time integration) and the implicit Discontinuous Galerkin model, IMPGD (P0/P0+ interpolation with implicit Euler scheme). For this study, the 3D finite element FORGE3® software is required.

In this paper, the behaviour of the tantalum subjected to a complex range of thermomechanical sol... more In this paper, the behaviour of the tantalum subjected to a complex range of thermomechanical solicitations is studied and modelled. The objective of this work is the prediction of microstructure evolution of a tantalum part that is cold flow-formed, then stress-relieved and softened by heat treatments. Flow forming is a cold chipless process that elongates and thins the wall of a tubular part by applying a free rotating roller on the wall of the rotating part. (See Figure 1) This process leads to large strain up to 5 and one material point may be deformed at a fluctuating strain rate. To model this process, it is thus recommended to use a constitutive law that takes into account the history of the material. Microstructure evolution is controlled through the whole process by monitoring the state variable, that is, the dislocation density, within a FEM code. The 3D FEM software FORGE2007® is used to model the entire process. The code is enhanced with physical constitutive laws relative to the tantalum and derived from works of Klepaczko and Buy et al. [1,2,3]. The formalism of Klepaczko and Buy et al. is useful since it is based on laws regulating physical mechanisms of dislocations multiplication, annihilation and kinetics of glide depending on strain rate and thermal activation. Static recovery is modelled subsequently with an incremental approach where the softening is related to the dislocation density evolution. A set of thermomechanical experiments and treatments are done to identify the constitutive law and associated microstructure evolution. Compression, dynamic and static torsion tests covering a wide range of strain rates are used to fit the mechanical constitutive law and the dislocation density evolution law both inspired from Klepaczko and Buy et al. works. The same samples are then annealed with variable temperatures and times. Microstructure of annealed samples is characterized by means of micro-hardness. They give information to evaluate the dislocation density evolution. The data is used to model static recovery.0.

Successful emergency management requires effective communication between the civil defence agenci... more Successful emergency management requires effective communication between the civil defence agencies and the community to provide and receive timely and accurate information, and identify needs and resources. Religious communities encompass a wide cross-section of social classes, socioeconomic indicators, ethnic groups and ages, and have their own internal communication structures. In this study, clergy in different Christian denominations were asked about their roles in the Canterbury earthquake sequence (CES), the needs of their congregations and the possibilities and obstacles to deeper collaboration with Civil Defence and Emergency Management (CDEM) authorities. Results show a lack of communication between CDEM and religious communities prior to and during the CES, and record suggestions from the participants on how links between organised religion and CDEM can be strengthened to build resilience for future disasters.