Issue 47

M.F. Funari et alii, Frattura ed Integrità Strutturale, 47 (2019) 277-293; DOI: 10.3221/IGF-ESIS.47.21 285 (a) (b) Figure 5 : Load – midspan vertical displacement relationship and DIC strain maps: (a) SCB specimen; (b) ASCB specimen. Divinycell H100 1c K [MPa m 0.5 ] 2 c K [MPa m 0.5 ] 1 max P [N] 2 max P [N] 0.222±0.001 0.116±0.002 334±1 628±5 Table 1 : Experimental results in terms SIFs and maximum load reached. S IMULATION OF THE INTERFACIAL DEBONDING n this section, the capability of the proposed model to predict the debonding failure mechanism in sandwich panels at the skin/core interface is verified by means of comparisons with numerical and experimental results available in literature. Structures featuring aluminum or glass/polyester face-sheets and different type of foam cores are taken in consideration. In detail, the static behavior of interfacial crack propagation at the upper interface between face-sheet and core is investigated on classical Double Cantilever Beam (DCB) and Mixed Mode Bending (MMB) loading schemes. Subsequently, the dynamic behavior is analyzed with the aim to identify the influence of inertial effects produced by different levels of loading rate and by different core typologies. Double Cantilever Beam As a first case study, the DCB loading scheme studied by Odessa et al. [32] is investigated. Fig. 6(a) illustrates the geometry of the specimen, as well as loading and boundary conditions, whereas mechanical properties assumed for the skins, core and interfaces, are summarized in Tab.2., according to data reported in [32]. Fig. 6(b) shows the dimensionless values of the opening force   c F G B and nominal crack tip position   T X L in function of the opening displacement, with reference to two different core thickness configurations, i.e. 15 20 mm c h   . The opening force values obtained are compared to both experimental [33] and numerical [32] results retrieved from literature, showing excellent agreement and demonstrating the capability of the model to efficiently simulate a mode I debonding phenomenon. It is also worth noting how an increment in the core thickness does not produce significant variations in the loading curve, due to the high deformability of the foam compared to the skin layers. I