Damage Mechanics Modelling of the shear nonlinear behavior of Nomex honeycomb core. Application to sandwich beams

Abstract

In this work, a modelling strategy based on damage mechanics is presented for Nomex honeycomb core. The proposed approach is based on the experimental analysis presented by the authors in [1] and consists of the decoupled modelling of the buckling and collapse of cells for the HRH-78 Nomex honeycomb core with two damage parameters. The proposed approach shows good agreement with the experimental tests. The computational cost is low, proving the efficacy of this technique. This strategy may avoid using full 3D models that mimic the real shape and is a step toward a full compression/shear nonlinear model for honeycomb core.

Insert of sandwich panels sizing through a failure mode map

“…This model is not as detailed as the models developed by Roy et al in [20], Seeman et al in [14,31] or Slimane et al in [32]. Instead, several simplifications proposed by ESA in [10] and the ideas and results presented previously in [27,33] are considered. These simplifications reduce the development and Fig.…”

“…As for the types of elements, only brick elements are used to represent the materials, including the skins, the honeycomb core, the potting and the fastener. For the core, this allowed the CDM approach presented in [33] to be implemented, providing a good alternative to include the shear nonlinear behavior of the core at low computational cost.…”

“…11-b). Finally, for the Nomex honeycomb core, the CDM approach presented in [33] is implemented. This method uses two different variables to consider, first, the effect of the elastic reversible buckling of the cells and, second, the permanent damage of the collapsing cells.…”

“…This approach is used to simulate the shear nonlinear behavior of the cells near and far from the insert. The coefficients of Table 2 refer to the approach presented in [33]. The nonlinear behavior of cells starts at γ b0 and they collapse at γ c0 .…”

“…For the meshing, the skins are composed of two layers and therefore they have two elements of thickness each. The core is meshed with only one element as explained in [33] and, for the rest of the parts, the size can vary according to the accuracy desired. Symmetry is considered and only one quarter of the specimen is modeled.…”