PhD thesis : "Transition from a nonlocal damage model to a cohesive zone model within the framework of quasi-brittle failure"

Sam Cuvilliez defend his PhD thesis on the subject "Transition from a nonlocal damage model to a cohesive zone model within the framework of quasi-brittle failure The" Wednesday, January 1st 2012 at 14:00, room L109, at l’École des Mines de Paris, 60 boulevard Saint-Michel, Paris.

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Abstract : The present work deals with the study and the improvement of regularized (non local) damage models. It aims to study the transition from a continuous damage field distributed on a structure to a discontinuous macroscopic failure model. First, an analytical one-dimensional study is carried out (on a bar submitted to tensile loading) in order to identify a set of interface laws that enable to switch from an inhomogeneous solution obtained with a continuous gradient damage model to a cohesive zone model. This continuous / discontinuous transition is constructed so that the energetic equivalence between both models remains ensured whatever the damage level reached when switching This strategy is then extended to the bi-dimensional (and tri-dimensional) case of rectilinear (and plane) crack propagation under mode I loading conditions, in a finite element framework. An explicit approach based on a critical damage criterion that allows coupling both continuous and discontinuous approaches is then proposed. Finally, results of several simulations led with this coupled approach are presented.

Keywords : Nonlocal damage model, cohesive zone model, energetic equivalence, finite element method.