Issue 41

A. Mardaliazad et alii, Frattura ed Integrità Strutturale, 41 (2017) 504-523; DOI: 10.3221/IGF-ESIS.41.62 518 Simulation of the four-point bending test Replication of the Flexural test was obtained by means of two numerical models that consists of rollers, compressive platens, steel blocks and the specimen. Due to the high computing time required for the KCC, and by help of the symmetric nature of the test, only one-quarter of the test was modelled in LS-DYNA (see Fig. 12a). Since the ghost particle methods (which is explained below) is not yet available in ABAQUS, the numerical model replicated in this software consists of the full model (see Fig. 12b). In all the models, the conversion to SPH particles is only considered for the rock specimen. The axes of rollers are fixed in the XY plane, while the displacement-controlled compressive loading is applied by the upper platens. The lower platens are limited to zero degree of freedom to represent the bed of the testing machine. The mechanical properties of these components are reported in Tab. 8. Figure 11 : The post-yield stress-strain diagram in compression. Figure 12 : The numerical models of Flexural test replicated in; (a) LS-DYNA, (b) ABAQUS. Rollers Platens Steel blocks Section Solid Shell Solid Material model Elastic Rigid Elastic Density [ton/mm 3 ] 7.85 e-9 7.85 e-9 7.85 e-9 Elastic modulus [MPa] 1.9 e5 2.1 e5 2.1 e5 Poisson ratio 0.3 0.3 0.3 Table 8 : The mechanical properties of the rollers, platens and steel blocks. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 p [mm/mm] 10 -3 0 10 20 30 40 50 60 70 [MPa] (a) (b)