O.P. Søvik

Bio: O.P. Søvik is an academic researcher. The author has contributed to research in topics: Damage mechanics & Nucleation. The author has an hindex of 1, co-authored 1 publications receiving 7 citations.

Experimental and Numerical Investigation of Void Nucleation in an AlMgSi Alloy

Abstract: The nucleation of microvoids from second phase particles in an AlMgSi alloy has been investigated. The work has comprised detailed stress analyses of elastic particles situated in an elastic-plastic matrix as well as damage mechanics analyses of the ductile fracture behaviour of smooth and notched axisymmetric tensile specimens. Based on the micromechanical analyses of isolated particles, general expressions relating local stresses in the particles to the stresses on a mesoscopic (continuum) level have been derived. These relationships have been incorporated into the classical Gurson model. Combined with a failure criterion based on a physical coalescence mechanism, a calibration with experimental results enabled the establishment of a set of micromechanical parameters which are transferable between different stress triaxialities.

Continuum mesomechanical finite element modeling in materials development: A state-of-the-art review *

Abstract: Advanced finite element techniques for the simulation of materials behavior under mechanical loading are reviewed. Advantages, limitations and perspectives of different approaches are analyzed for the simulation of deformation, damage and fracture of mate

Simulation physique des conditions thermomécaniques de forgeage et d'usinage : caractérisation et modélisation de la rhéologie et de l'endommagement

Abstract: Au cours des procedes de forgeage et d'usinage, le materiau subit des deformations rapides et importantes provoquant des echauffements localises, des changements microstructuraux et de l'endommagement La modelisation de tels phenomenes necessite la connaissance precise des lois de comportement et d'endommagement sur une tres large gamme de deformations, vitesses de deformation, et temperatures Des essais de compression conduits en utilisant le simulateur thermomecanique GLEEBLE et le banc d'Hopkinson sur deux aciers, 42CrMo4 et 100Cr6, et un alliage d'aluminium 2017-T4, permettent de distinguer trois domaines de comportement : a froid, a mi-chaud et a chaud Les phenomenes microstructuraux rencontres dans chaque domaine sont analyses et relies au comportement rheologique observe Apres une comparaison de differents modeles de la litterature, un modele empirique est propose Il rend efficacement compte de la competition entre l'ecrouissage et l'adoucissement et permet de refleter, via un couplage, les effets de temperature et de vitesse de deformation Une caracterisation des mecanismes d'endommagement est conduite, a froid, a l'aide d'essais de traction in situ dans un Microscope Electronique a Balayage et de la methode de correlation d'images numeriques En temperature, des essais de traction sur eprouvettes axisymetriques entaillees sont utilises Deux modeles d'endommagement sont identifies et analyses, le critere de rupture decouple de Johnson-Cook et le modele micromecanique couple de Gurson-Tvergaard-Needleman Les differents modeles de comportement etudies sont enfin utilises et discutes dans le cadre de simulations Elements Finis de la coupe orthogonale, du cisaillement sur eprouvette " chapeau " et du bipoinconnement

Caractérisation à la rupture de matériaux ductiles par approche locale

Abstract: This thesis is a contribution to the study of the ductile fracture phenomenon of porous materials. Firstly, a review on the ductile fracture divided in two main parts is presented. The first part concerns the elastic plastic fracture mechanics that is represented by the J-Integral. The other part is dedicated to the micromechanical approach of the ductile fracture. A numerical and experimental study of the AISI 304L thin sheets is proposed. Firstly, the ductile fracture phenomenon is simulated using the GTN and Rousselier models. An hybrid approach combining experimental tests on CT specimens and simulations using the GTN model in order to assess the fracture toughness is proposed. The EWF method is also used with a numerical validation using a cohesive zone modeling. In the third chapter, an identification method for the GTN model parameters identification is proposed. The method is based on the hierarchy of the void volume fraction parameters evolution until the final fracture. In the fourth chapter, the mechanical response of porous materials is studied using the numerical homogenization. The GTN model is extended to take into account a wide range of porous materials. Finally, an experimental validation is proposed.