Issue 41

M.F. Funari et alii, Frattura ed Integrità Strutturale, 41 (2017) 524-535; DOI: 10.3221/IGF-ESIS.41.63 534 particular, in order to satisfy the solution accuracy, the numerical model arising from [18] is based on a discretization with 560 and 320 elements for the steel and FRP strip layer, respectively. Moreover, the discretization of the 2D adhesive layer presents a uniform length equal to 0.5. As a consequence, the total number of DOFs is approximately 7100. Contrarily, by using the proposed approach, in which also the adhesive layer is simulated by means the shear deformable beam elements, the number of variables is strongly reduced. In particular, the proposed model has been discretized by means a uniform mesh length equal to 1 mm for the laminate and 1 mm for the interface involving 3018 DOFs. Therefore, a computational saving approximately equal to 60% is achieved. Figure 9 : Comparisons in terms of interfacial tractions across the two cohesive interfaces for different positions of debonding front: X =0mm as T (a) ; X =25mm as T (b) ; X =50mm as T (c) ; X =75mm as T (d) . C ONCLUSIONS he proposed model is developed with the purpose to study the delamination processes in layered structures. The work flow is based on two different stages solved simultaneously, which are devoted to identify onset crack position along the interfaces and the corresponding evolution. Compared with existing formulations available from literature, this model presents lower computational efforts and complexities in the governing equations. As a matter of fact, the use of debonding length concept coupled with a moving mesh approach based on ALE formulation strongly reduces the computational complexities, since the mesh discretization is concentrated on a small portion coinciding to the process zone or the characteristic fracture length of the laminate. Finally, the numerical approach is quite general since it does not depend from TSL or the structural formulation and can be easily implemented in conventional FE software. In order to validate the proposed model comparisons with numerical results obtained by pure cohesive approach are reported. Finally, some parametric studies have been developed in terms of geometric characteristics of the layered structures for FRP strengthened steel beams, which reveal a good agreement with existing results available from the literature. T