Comparison between experimental and numerical results of mixed-mode crack propagation in concrete: Influence of boundary conditions choice

International audienceno abstrac

Phase-field simulation of interactive mixed-mode fracture tests on cement mortar with full-field displacement boundary conditions

International audiencePhase-field modeling is an elegant approach to simulate complicated fracture processes, including crack initiation, propagation, merging and branching in a unified framework without the need for ad-hoc criteria and on a fixed mesh. These capabilities can only be fully validated through the comparison with experiments featuring crack development histories and patterns of sufficient complexity. As opposed to conventional mixed-mode fracture tests with predefined loading, interactive tests with multiaxial loading which are controlled during the propagation of the cracks can create more complex and stable crack propagation patterns. Moreover, the development of measurement techniques such as digital image correlation (DIC) provides the possibility to quantitatively characterize the full-field kinematics during the tests. In this work, full-field displacements measured by DIC during interactive mixed-mode fracture tests on cement mortar specimens are adopted as boundary conditions for phase-field numerical simulations. Qualitative and quantitative comparisons are illustrated, demonstrating the capability of the phase-field approach to predict complex mixed-mode fracture phenomena in cement mortar and suggesting possible further developments

Digital image correlation & Fracture mechanics: Brittle Fracture of Ceramics and Refractories

International audienc

A complex mixed-mode crack propagation test performed with a 6-axis testing machine and full-field measurements propagation

International audienceA new type of mixed mode crack propagation test is proposed. A single crack is initiated and propagates in a stable way up to complete failure. A combination of tensile, shear and in-plane rotation performed by a 6-axis testing machine is prescribed. The rotation creates a tension/compression gradient in the sample ensuring the stability, while the shear direction is closely related to the orientation of the crack and the tensile load is responsible for the actual propagation. The experiment is performed in an interactive manner, namely, depending on the crack tip position estimated by Digital Image Correlation (DIC) during the test, the loading is changed to bifurcate the crack. The displacements of the sample surfaces are assessed using multiple DIC measurements and displacement sensors. The displacement fields on each face of the sample give access to the crack pattern, and also to the actual boundary conditions that are crucial for a faithful numerical analysis of the test. Last, the 6 load components are recorded enabling for a complete description of the 3D mechanical behavior of the specimen