Issue 41

M.F. Funari et alii, Frattura ed Integrità Strutturale, 41 (2017) 524-535; DOI: 10.3221/IGF-ESIS.41.63 531 IC G [N/mm] c n T [MPa] 0 n Δ [mm] n Δ c [mm] IIC G [N/mm] c T t [MPa] 0 Δ t [mm] Δ c t [mm] 0.26 30 0.00173 0.0173 1.02 60 0.00334 0.0334 Table 2 : Interface properties of the laminate. In Fig. 5a, results in terms of resistance curve are reported. The loading curve, obtained by the proposed model, is in agreement with the results obtained by using refined CZM approach. Moreover, in the case of a very low mesh element number (M1), the prediction in terms of resistance curve is not affected by a divergent behavior, but it is always very close to enriched one, namely PC1. In Fig. 5b, the evolution between crack tip and applied displacements for two different mesh discretizations are considered. The results show that the proposed model is quite stable, since the predictions in terms of crack tip displacements coincide with that of the PC1 solution. However, it should be noted that in the case of a pure cohesive approach, the crack tip position is taken as the point where the fracture function of the cohesive interface tends to zero, whereas, in the proposed model, an explicit movement of ALE region is identified, since it corresponds to a variable which enters in the computation. Figure 5 : Comparisons in terms of loading curve with pure cohesive approach (a) ; Comparisons in terms of cracks tip position with pure cohesive approach (b) . Figure 6 : Steel beam configuration and loading scheme. FRP strengthened steel beam specimen The analyses are developed with reference to loading schemes based on the 4-point bending, in which the dynamic effects are considered from both onset and evolution mechanisms. The loading, the boundary conditions and the geometry are illustrated in in Fig. 6, whereas the mechanical properties assumed for the steel, the adhesive, the FRP strip and those