VDT microplane model with anisotropic effectiveness and plasticity

Abstract

L'état de l'ouverture et de la fermeture des microfissures est un phénomène cinématique généralement modélisé à l'aide de variables d'effectivité de l'endommagement, qui conduit à une élasticité différente pour un même niveau de dommage. Dans ce travail, le modèle microplan avec une décomposition Volumétrique, Déviatorique et Tangentiel (VDT), est sélectionné et modifié en introduisant l'effet d'ouverture-fermeture des microfissures dans l'énergie libre. Une loi d'évolution de l'endommagement est écrite pour mieux prendre en compte l'influence de la pression sur l'endommagement. Afin de mieux illustrer les mécanismes introduits dans le modèle, des rosettes de dommage pour un niveau de déformation donné sont présentées. Le modèle est validé en comparant les simulations aux résultats expérimentaux pour des essais monotones et cycliques de traction et compression avec différents niveaux de confinement. Abstract:The opening-closing state of the microcracks is a kinematic phenomenon usually modeled using a set of damage effectiveness variables, which results in different elastic responses for the same damage level. In this work, the microplane model with volumetric, deviatoric and tangential decomposition denoted V-D-T is modified. The influence of the confining pressure is taken into account in the damage variables evolution laws. For a better understanding of the mechanisms introduced into the model, the damage rosettes are presented for a strain given level. The model is confirmed through comparisons of the simulations with the experimental results of monotonic, and cyclic tensile and compressive testing with different levels of confining pressure.

Quasistatic mechanical behavior of HMX- and TATB-based plastic-bonded explosives

“…With this formulation, the crack growth rate c depends only on the deviatoric stress and therefore is pressure-independent, unlike in the SCRAM model (previous equations (8) and (9)).…”

“…Taking up the cyclic tests on M1, Benelfellah and coworkers (Benelfellah, 2013;Benelfellah et al, 2014Benelfellah et al, , 2017Picart et al, 2014) were interested in the induced anisotropy of the material highlighted by these tests. The authors determined longitudinal and transversal elastic moduli for each loading cycle.…”

“…The model coupled a damage-induced anisotropy (Benelfellah, 2013;Benelfellah et al, 2014Benelfellah et al, , 2017Picart et al, 2014) with the plasticity model proposed by Le et al (2010), denoting ℂ d the damaged stiffness:…”

“…To describe the anisotropy of the damaged stiffness tensor, Benelfellah et al have chosen a microplane approach (Benelfellah et al, 2014(Benelfellah et al, , 2017. In this model, each microplane is defined by its normal n and the elastic strains tensor is split in three components (volumetric, deviatoric and tangential) as follows (Carol and Bazant, 1997): Let us note that the volumetric projection V is not dependent on the microplane.…”

“…Zubelevicz et al (2013) have introduced different damage rates in tension and compression coupled with viscoplasticity. Lastly, a microplane model with anisotropic damage added to non-associated plasticity with isotropic hardening was proposed by Benelfellah et al (Benelfellah, 2013;Benelfellah et al, 2014Benelfellah et al, , 2017Picart et al, 2014).…”