Reference : Damage to crack transition for ductile materials using a cohesive-band /discontinuous...
Scientific congresses and symposiums : Unpublished conference/Abstract
Engineering, computing & technology : Materials science & engineering
Engineering, computing & technology : Mechanical engineering
http://hdl.handle.net/2268/233781
Damage to crack transition for ductile materials using a cohesive-band /discontinuous Galerkin framework
English
Leclerc, Julien mailto [Université de Liège - ULiège > Département d'aérospatiale et mécanique > Computational & Multiscale Mechanics of Materials (CM3) >]
Nguyen, Van Dung mailto [Université de Liège - ULiège > Département d'aérospatiale et mécanique > Computational & Multiscale Mechanics of Materials (CM3) >]
Wu, Ling mailto [Université de Liège - ULiège > Département d'aérospatiale et mécanique > Computational & Multiscale Mechanics of Materials (CM3) >]
Noels, Ludovic mailto [Université de Liège - ULiège > Département d'aérospatiale et mécanique > Computational & Multiscale Mechanics of Materials (CM3) >]
13-Mar-2019
No
Yes
International
Colloquium 600 New challenges in finite element technology – from the perspective of mechanics and mathematics
12-14 March 2019
Euromech 600
Aachen
Germany
[en] Damage ; Gurson ; Thomason ; Cohesive Band ; Crack
[en] Numerical predictions of the ductile failure process are still challenging. Indeed, such failure combines a diffuse damage stage followed by damage localisation and crack initiation/propagation. On the one hand, continuous damage models are suited for the diffuse damage stage but not for the description of physical discontinuities.
On the other hand, discontinuous approaches, such as cohesive zone models, can reproduce crack initiation and propagation, but not the diffuse damage stage.
In this work, we present a numerical scheme combining both approaches in a discontinuous Galerkin finite element framework. First, a non-local implicit damage model computes the initial diffuse damage stage beyond the softening point without mesh-dependency. Second, a crack is introduced using a cohesive band [1,2]. Contrarily to classical cohesive models, a 3D state is recreated at the crack interface by considering a small, but finite, fictitious cohesive thickness allowing a strain tensor to be evaluated from the cohesive jump and the neighbouring bulk deformation gradient. A stress tensor at the interface, from which the cohesive forces are deduced, is computed using an appropriate local damage law.
The ductile failure is thus modelled by a combination of the Gurson and the Thomason evolution laws [3]. First, the initial diffuse void growth phase is modelled by the (non-local) Gurson model [4] accounting for shear effects [5]. Second, a crack is introduced when the coalescence is reached and the behaviour of the cohesive law is computed from the Thomason model [3]. The framework capabilities are demonstrated by reproducing the slanted and the cup-cone failure respectively of a plane strain specimen and a round bar.

Ack.: The research has been funded by the Walloon Region under the agreement no.7581-MRIPF in the context of the 16th MECATECH call.

REFERENCES
[1] J.J.C. Remmers, R. de Borst., C.V. Verhoosel and A. Needleman. “The cohesive band model: a cohesive surface formulation with stress triaxiality”, Int. J. Fract. 181 (2013).
[2] J. Leclerc, L. Wu, V.D. Nguyen and L. Noels, “Cohesive band model: a cohesive model with triaxiality for crack transition in a coupled non-local implicit discontinuous Galerkin/extrinsic cohesive law framework”, Int. J. for Num. Methods in Eng. (2018)
[3] A.A. Benzerga, J.-B. Leblond, A. Needleman, V. Tvergaard. Ductile failure modelling. Int J Fract 201 (2016).
[4] F. Reusch, B. Svendsen and D. Klingbeil. A non-local extension of Gurson-based ductile damage modelling. Comp. Mat. Sci. 26 (2003).
[5] K. Nahshon and J.W. Hutchinson, “Modification of the Gurson Model for shear failure”, European Journal of Mechanics A/Solids 27 (2008).
A&M
Service public de Wallonie : Direction générale opérationnelle de l'économie, de l'emploi et de la recherche - DG06
The research has been funded by the Walloon Region under the agreement no.7581-MRIPF in the context of the 16th MECATECH call.
Researchers ; Professionals ; Students
http://hdl.handle.net/2268/233781

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