PSI - Issue 33

Umberto De Maio et al. / Procedia Structural Integrity 33 (2021) 954–965 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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approach is almost superposed to that obtained via the reference model. The overestimation of the load-carrying capacity predicted by the DIM respect to the ECM model is due to the toughness increment induced by the random distribution of the cohesive interface elements in which the crack is forced to propagate. The crack patterns, reported in Fig. 5, predicted by the two models at simulation steps A and B, highlighted in loading curve of Fig. 4, are globally in a good agreement with that obtained by the reference numerical model. However, the DIM model predicts a notably jagged path respect to that obtained by the ECM model due to the fact that the crack develops along the interelement boundaries of the adopted unstructured mesh.

Fig. 5. Comparison between the numerically predicted main crack path obtained by plotting the damage variable along the interface and within the solid elements for DIM and ECM, respectively.

3.2. Mixed-mode crack propagation analysis Here, to assess the capabilities of the two adopted models to analyze the cracking behavior under general loading conditions, where the crack path is not a priori known, the simulation of a mixed mode fracture test, involving the L shaped panel made of plain concrete already analyzed experimentally in (Winkler, 2001), have been performed. The geometric configuration and boundary conditions of the simulated test are illustrated in Fig. 6. The Young’s modulus and Poisson’s ratio of the elastic bulk material have been set equal to 25,850 MPa and 0.18, respectively. The inelastic parameters, required by the traction separation laws adopted by the DIM and ECM models, are listed in Table 2.

Fig. 6. L-shaped concrete specimen: (a) geometric configuration and boundary conditions (all dimensions are expressed in mm); (b) the unstructured and (c) structured tessellations performed in the damage zone for the DIM and ECM simulations, respectively.