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Discrete Element method, a tool to investigate contacts in materialformingI. Iordanoff 1 , D. Richard 2 , S. Tcherniaieff 11 ARTS ET METIER PARITECH, LAMEFIP – Esplanade des ARTS et Metiers, Talence, FRANCEURL: www.lamef.bordeaux.ensam.fre-mail: ivan.iordanoff@lamef.bordeaux.ensam.fr; Serge.tcherniaeff@bordeaux.ensam.fr2 INSA de LYON, LAMCOS – 18-20 Rue des Sciences, 69621 Villeurbanne Cedex, FRANCEURL: lamcos.insa-lyon.fre-mail:david.richard@insa-lyon.fr;ABSTRACT: This paper is devoted to the description of a numerical tool that allows the local study ofcontacts in material forming: Discrete Element Method (DEM). Discrete Element Methods allow the study oflocal properties (cohesion, thermal generation, fractures) on process behavior. This tool is used as moleculardynamics but allows the simulation of much representative volumes. Discrete element method is applied as atool to understand/propose/confirm, physical scenario involved in the contact zone. It is shown in this paperhow such numerical simulations can be used as a complementary tool for forming processes study. Examplesare given on thermal study in cutting process, subsurface damages analysis in abrasion process and weldingjoint characterization in Friction Stir welding.Key words: Discrete Element Method, Abrasion process, Friction Stir welding, Tool Machining.1 INTRODUCTIONDiscrete element method has been widely developedfor rheological study of true discrete materials likesand, powder and granular materials [1]. In the pastten years, their fields of applications have beenextended to heterogeneous materials like concrete,biological materials or foams. Their ability tosimulate multi body behavior is used for problemswhere:- A great number of dissociated elements mustbe taken into account,- A great number of default is encounteredThe main recent fields of applications are multifracturesproblems, where detached elements mustbe taken into account (wear in tribology [2],avalanches in geophysic, milling, grinding …).In material forming or cutting, the contact zonebetween the tool and the working piece is often verydifficult to analyze because:- The affected area has little dimension,- High mechanical, rheological, thermalgradient are involved,- Physical phenomena are highly dynamic.To analyze the contact behavior Godet developedthe third body concept [3]. This included adescription of the formation and movement offragmented particles in the interface region. Tostudy the behavior of the third body inside andoutside the contact, Berthier proposed [4] thetribological circuit which allows the study of masstransfers inside the contact. Based on thistribological circuit and coupling Discrete Elementmodels (DEM) to experimental, but simplified, wearstudies, Fillot et al [5] proposed a set of equationsthat allows a qualitative modeling of wear as a massbalance in the contact area. Iordanoff et al. [6]showed how abrasion process can be studied as aparticular and controlled wear process.This paper first presents the Discrete ElementMethods developed in the special case of materialforming. Then, three examples are given to illustratehow this numerical tool can be used to study localproperties in material forming: investigation of SubSurface Damage in abrasion process, welding jointcharacterization in Friction Stir welding and thermalinvestigation of the tool-chip contact during cuttingoperation.