Initiation and propagation of complex 3D networks of cracks in heterogeneous quasi-brittle materials: Direct comparison between in situ testing-microCT experiments and phase field simulations

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• 作者：T.T. Nguyen^a ; ^b ; J. Yvonnet^a ; ^{julien.yvonnet@univ-paris-est.fr" class="auth_mail" title="E-mail the corresponding author} ; M. Bornert^b ; C. Chateau^b
• 关键词：Micro cracking ; Quasi-brittle ; Heterogeneous material ; Phase-field method ; Gradient damage model ; Voxel-based models ; In situ testing ; X-ray microtomography ; Digital volume correlation
• 刊名：Journal of the Mechanics and Physics of Solids
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：95
• 期：Complete
• 页码：320-350
• 全文大小：11479 K

文摘

We provide the first direct comparisons, to our knowledge, of complex 3D micro cracking initiation and propagation in heterogeneous quasi-brittle materials modelled by the phase field numerical method and observed in X-ray microtomography images recorded during in situ mechanical testing. Some material parameters of the damage model, including the process zone (internal) length, are identified by an inverse approach combining experimental data and 3D simulations. A new technique is developed to study the micro cracking at a finer scale by prescribing the local displacements measured by digital volume correlation over the boundary of a small sub-volume inside the sample during the numerical simulations. The comparisons, performed on several samples of lightweight plaster and concrete, show a remarkable quantitative agreement between the 3D crack morphology obtained by the model and by the experiments, without any a priori knowledge about the location of the initiation of the cracks in the numerical model. The results indicate that the crack paths can be predicted in a fully deterministic way in spite of the highly random geometry of the microstructure and the brittle nature of its constituents.