Issue 30

D. Tumino et alii, Frattura ed Integrità Strutturale, 30 (2014) 317-326; DOI: 10.3221/IGF-ESIS.30.39 320 At this stage, an analytical homogenized formulation of the transversal shear stiffness has not been obtained yet. For this reason, case studies here analyzed will concern applications where the shear deformation can be neglected (for example because of the presence of a PVC filler in the corrugation). Figure 1 : Axonometric view of the sandwich (left), definition of geometric parameters of the transversal section (middle), homogenised unit cell (right). N UMERICAL ANALYSES Validation of the analytical model he analytical model of homogenization has been validated with 3D Finite Element analyses on the unit cell subjected to simple load systems. In Fig. 2 loads and boundary constrains used to evaluate entities in eq (1-3) are shown. In particular, in each case a displacement field has been applied to the free section of the unit cell in order to reproduce the deformation occurring by applying a rotation in x or in y or in xy. Then, the total reaction force was calculated in correspondence of the constrained section and the stiffness obtained dividing the reaction by the imposed rotation. Figure 2 : Load and constraint schemes to evaluate out of plane stiffness of the sandwich. The model used for simulations is depicted in Fig. 3: a mapped mesh is obtained with Solid hexaedral elements in APDL Ansys [39]. The material model used is linear orthotropic and elastic constants of the material used are summarized in Tab. 1, together with main dimensions of the unit cell. Figure 3 : FEM model used to validate the analytical formulation. T