Abstract :
[en] Localization in a quasi brittle material is studied using a local second gradient model. Since localization takes place in a medium assumed to be initially homogeneous, non uniqueness of the solutions of an initial boundary value problem is then also studied. Using enhanced models implies to generalize the classical localization analysis, especially it is necessary to study
solutions more continuous (i.e., continuous up to the degree one) than the ones used in analysis involving classical constitutive equations. Within the assumptions done, it appears that localization is possible in the second gradient model if it is possible in the underlying classical model. Then the study of non uniqueness is conducted for the numerical problem, using different first guesses in the full Newton-Raphson procedure solving the incremental non
linear equations. It turns out ¯nally that we are able thanks to this method to reproduce qualitatively the non reproducibility of usual experiment in the post peak regime.
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