Ligament size effect in largely cracked tensile structures

The influence of the ligament size on the brittle failure behaviour of largely cracked elements is analysed. To this aim, the following tensile infinite geometries are taken into account: (i) a double edge cracked plate; (ii) a cylindrical bar with an external circular crack. These configurations can be considered as complementary to the Griffith crack and the Penny shaped crack, respectively. The failure size effect is investigated through a semi-analytical approach by two different methods: the coupled Finite Fracture Mechanics (FFM) criterion and the Cohesive Crack Model (CCM) implementing a Dugdale type cohesive law. Theoretical predictions are compared with each other and with experimental data obtained by tensile testing PMMA samples containing two collinear cracks. Strength estimations reveal accurate.