PSI - Issue 66

Gabriele Cricrì et al. / Procedia Structural Integrity 66 (2024) 82–86 Author name / Structural Integrity Procedia 00 (2025) 000–000 the two equations (9) are decoupled since the second one only depends on and can be solved first to get the incremental crack vector that allows computing the load ∆ upon substitution into the first equation. As shown later on in the numerical example, the magnitude of the predefined crack increment ∆ strongly affects the crack path at solution. Clearly, for the ideal homogeneous brittle case the converged solution is obtained in the limit for vanishing ∆ ; however, should the material strength be characterized by a microstructure, the crack extension increment ∆ to be used in calculations had better be related to the small-scale characteristic length. 4. Numerical example We study the L-shaped concrete panel depicted in Figure 1. Experimental results are available from Winkler (2001) for this well-known mixed-mode problem, which has been used as a benchmark by a number of authors to assess the ability of damage models to capture curved crack paths. 85 4

Fig. 1. L-shaped panel. Model problem (left) and experimental crack paths (right). All dimensions in mm.

The specimen is fully clamped at the bottom edge; loading is applied by prescribing an upward vertical displacement on the lower horizontal leg at a distance of 30 mm from the right edge and the corresponding reaction force is recorded. Material parameters are taken as follows: Young modulus = 20 GPa, Poisson ratio = 0.18, tensile strength � =2.70 MPa and critical fracture energy � = 0.095 N/mm. The structure has been analyzed under plane stress conditions using a non-uniform unstructured mesh made of quadrilateral elements.

Fig. 2. L-shaped panel. Computed VS experimental crack paths.