Developments in finite element simulations of continuous casting

peer reviewedTwo complementary approaches of steel continuous casting modelling using the finite element code LAGAMINE have been developed in the M&S Department. We propose here a description of the context in which the study started, then a description of both macroscopic and mesoscopic approaches. The first one describes the whole continuous casting process, from the free surface in the mould and through the entire machine, including thermal and mechanical behaviour of the steel. The second approach focuses on the prediction of cracks and is developed at the grain scale. Some results are also presented for both models

Prediction of distortion during cooling of steel rolled rings using thermal-mechanical-metallurgical finite element model

peer reviewedThis work takes place in the framework of a CRAFT European project gathering three universities, three companies who produce rings through the ring rolling process and a manufacturer of temperature and dimension measurement devices. The final goal of the project is to develop and set up a system, integrated in the industrial process, capable of predicting the geometrical characteristics of final pieces just after the ring rolling stage and to allow the rolling process to avoid dimensional defects through online adaption. In fact, ring rolling production does not imply only the rolling process, but also the cooling and quench stages of steel rings. During all these phases, the dimensions of the pieces change dramatically. In particular, due to the lack of symmetry in the cooling conditions, ring distortions include contraction and rotation of the ring section. The modeling of the cooling phase requires taking into account a large number of phenomena resulting from the coupling of thermal, mechanical and metallurgical effects. A numerical model has been implemented in the non-linear finite element code LAGAMINE, developed by the University of Liège. Such a model can help to better understand the evolution of the geometry during the cooling phase and also the effects of each physical and microstructural parameter implemented in the model on the ring final shape. Effectively, several parameters can affect the ring distortions and the model should take them into account; in particular, the mechanical and thermal behavior of each phase present in the material (metastable austenite, ferrite, pearlite, bainite and martensite). Phase transformation modeling implies the integration of a wide data base of material properties (thermo-physical and mechanical properties of the phases, TTT and CCT diagrams, enthalpy and strain of phase transformation, strain of transformation plasticity…) but only a few of these data are available in literature. Some of them have been found for the reference material (42CrMo4 steel), but additional laboratory experiments have been performed at the Universities of Padua and Liège in order to characterize thermal, mechanical and plastic behaviour of phases. Finally, this paper presents the model validation on an industrial case (measurements of temperature and dimensions of rings have been provided by the manufacturer). Then, some applications are presented, demonstrating the importance of some factors such as some material properties, the shape of the rings, the type of cooling (and the cooling rate) or the symmetry of the cooling scheme on final ring distortion

Continuum mechanics in finite deformation: Proposing constitutive laws in finite deformation

Maste

Continuum mechanics in finite deformation: Proposing constitutive laws in finite deformation

Maste

Asynchronous interface between a finite element commercial software ABAQUS and an academic research code HEREZH++

WOSInternational audienceThe aim of this paper is to describe an efficient method to connect two independent softwares so as to jointly use best qualities of each software around a complex problem solved by the finite element method (FEM). This connection makes it possible to extend quickly and easily the applicability of new models developed in academic softwares, by their simultaneous use with commercial softwares. This is particularly interesting when these models are very difficult to implement directly in commercial softwares. Most of the commercial FEM applications allow users to add additional features, physical models or boundary conditions via a programming interface. Within these user routines, access to internal data structures is possible, either through subroutine parameters and global variables, or via internal modules for reading and storing data. We use these capabilities to link the commercial software ABAQUS and an academic object-oriented C++ software HEREZH++, via the user-defined mechanical material behaviour (Umat). In this interface, HEREZH++ computes the mechanical behaviour of material and the code coupling performs a communication procedure between ABAQUS and HEREZH++. This paper describes this architecture which allows to implement easily original behaviour law in the commercial ABAQUS code. The asynchronous code coupling is made with a named piped interprocess communication method and an interface written in c/C++. Several test samples are presented to show the efficiency and accuracy of the proposed implementations concerning the computational time. In particular, an industrial test is carried out with an original behaviour model of elasto–viscohysteresis which would have been very difficult to implement directly in ABAQUS. 2008 Elsevier Ltd. All rights reserved

Caractérisation du comportement cyclique d'un matériau tissé en traction ondulée

Colloque avec actes et comité de lecture. Internationale.International audienceDes résultats expérimentaux sur un matériau tissé en fils de polyamide 6-6 (PA66) sont présentés. Les essais ont été effectués d'une part en traction monotone à différentes vitesses de déformation et d'autre part en sollicitations cycliques sophistiqués de type traction ondulée avec des séquences de fluage ou de relaxation

Strain-space multi-surface Saint-Venant model to describe multiaxial elastic-plastic cyclic behavior

International audienc

An original flow rule for strain-space multi-surface Saint-Venant plasticity model

International audienceThe one-dimensional Saint-Venant model can reproduce the elastic-plastic uniaxial behavior of metallic materials. A three-dimensional extension of this model is proposed, to simulate the cyclic elastic-plastic multiaxial behavior for complex loading paths. A multi-surface model is obtained and an original flow rule, defined in the strain space, is considered. This model has been implemented in a commercial finite element code. The model response is investigated for different loadings and compared to experimental data from the literature. The model showed accurate response in the multiaxial case of tension-torsion experiments

Shooting the breeze

International audienc

Instrumented micro-hardness used to describe the gradients of mechanical constitutive behaviour

International audienc