In-Plane Thermal Characterization of Fiberglass/Phenolic Honeycomb Core through an Experimental-Numerical Approach

In the present study, a series of in-plane quasi-static tensile and compressive tests are carried out on a commercial Fiberglass/Phenolic hexagonal cell honeycomb core at elevated temperatures to investigate the high temperature mechanical responses of the bulk core under large deformations. Dynamic Mechanical Analysis (DMA) testing is also conducted on the core cell walls to determine the temperature dependence of the mechanical properties of the constituents of the core. A 3D non-linear finite element model (FEM) with large displacements of the repetitive unit cell is employed in which the cell walls, node bond adhesive layers and adhesive fillets at the intersections of the cell walls are modeled based on the measured geometry of a commercial Fiberglass/Phenolic honeycomb core. The homogenized stress-strain curves obtained from test data for uniaxial tension and compression loadings along the ribbon and transverse directions at different temperatures are compared with finite element predictions. It is shown that, by increasing the temperature, the honeycomb core responses to applied displacements become softer in both the ribbon and transverse directions, which are attributed to the degradation of phenolic resin used in the cell wall matrix and node bond adhesive. The predictions of the finite element model are in good agreement with the test data.