###### Abstract  
Simulation of fracture in fiber-reinforced plastics (FRP) and hybrid composites is a challenging task. This paper investigates the potential of combining the extended finite element method (xFEM) and cohesive zone method (CZM), available through LS-DYNA commercial finite element software, for effectively modeling delamination buckling and crack propagation in fiber metal laminates (FML). The investigation includes modeling the response of the standard double cantilever beam test specimen, and delamination-buckling of a 3D-FML under axial impact loading. It is shown that the adopted approach could effectively simulate the complex state of crack propagation in such materials, which involves crack propagation within the adhesive layer along the interface, and its diversion from one interface to the other. The corroboration of the numerical predictions and actual experimental observations is also demonstrated. In addition, the limitations of these numerical methodologies are discussed. delamination; extended finite element method; cohesive zone modeling; fiber-metal laminates; LS-DYNA +
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CZM is a relatively easy method to implement [2]; however, it requires a priori knowledge of the crack path, unless coupled with an advanced re-meshing technique [3,4]. The technique has been used in a variety of applications [5; 6; 7], because it is especially suitable for modeling interfaces in hybrid material systems; it also works well under large deformation conditions. Moreover, CZM can also be used to account for thermal [8] and moisture [9] effects, and also fatigue [10; 11]. For instance, [PERSON] et al. [12] used CZM to model the low-velocity impact of a vehicle's sub-structure constituted of various bonded components. Accurate results were obtained when the mesh discretizing the cohesive zone was significantly fine. Moreover, the suitability of the method for large-scale simulations was also demonstrated. [PERSON] et al. [13] showed another application of CZM, when it was used to assess the performance of bonded joints mating composite components in a ship, obtaining close an agreement between the numerical results and experimental data. [PERSON] et al. [14] used cohesive elements and tiebreak contact in LS-DYNA to simulate delamination between plies of fiber-reinforced polymers (note that tiebreak contact is also based on a cohesive zone algorithm). They obtained excellent results compared to their experimental results. In that study, each composite ply was modeled separately with either thin or thick shell elements, and the elements were then mated using cohesive elements or tiebreak contact. The xFEM approach involves \"enriching\" the finite element formulation to account for the presence of a discontinuity, without the need for creating an actual discontinuity between the elements, thus removing the need for remeshing [15; 16; 17]. A detailed explanation of the method's implementation in LS-DYNA can be found in [18]. The use of xFEM would be most effective when the crack path is unknown, or in cases where a crack is suspected to kink or bifurcate. This method has been recently utilized by several researchers to simulate crack initiation and propagation in various media. For instance, [PERSON] et al. [19] analyzed the failure of a biaxially loaded cruciform specimen made of quasi-isotropic chopped strand mat-reinforced composite using xFEM and showed that no prior knowledge of the onset location of the crack was necessary to obtain an accurate prediction of crack initiation and propagation. This is a significant advantage of xFEM compared to CZM. [PERSON] and [PERSON] [20] used xFEM to model delamination in composites and showed that the interfacial failure of the plies and cracking of the laminate could be simulated with virtually no-mesh dependency. [PERSON] et al.