Issue 31

J.A.F.O. Correia et alii, Frattura ed Integrità Strutturale, 31 (2015) 80-96; DOI: 10.3221/IGF-ESIS.31.07 89 model). Besides the symmetry boundary conditions, the pilot node controlling the pin displacement was restricted along the loading direction. Finally, the load was applied directly to the pilot node. It is interesting to note that the crack was modelled with a tip radius of ρ* , according the assumptions of Fig. 1b. The mesh size at crack tip was calibrated using a convergence study taking into account the elastic stresses along the crack plane ( σ x : crack plane direction; σ y : crack plane normal direction). Fig. 10 illustrates the crack tip meshes considered in this convergence study and mesh 2 was the one adopted for the numerical simulations. Tab. 3 presents the maximum elastic stresses ( σ x and σ y ) ahead of the crack tip, resulting from distinct mesh densities, for the S355 steel. The results are compared between the adopted reference mesh 2 and the other tested meshes. Mesh 2 gives a good compromise between computational cost and stability of the solution. 0 100 200 300 400 500 600 700 0.00E+00 1.00E‐02 2.00E‐02 3.00E‐02 4.00E‐02 5.00E‐02 Strain [‐] Stress [MPa] Ramberg‐Osgood FEM ‐ Multilinear Figure 9: Cyclic curve of the S355 steel. Mesh 5 Mesh 4 Mesh 1 Mesh 2 Mesh 3 Figure 10: Finite element meshes used in the convergence study for the S355 steel ( ρ* =55µm).

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