Equivalent properties of composite sandwich panels with honeycomb-grid hybrid core

Combining the complementary properties of honeycomb cores and grid cores, a composite sandwich panel with honeycomb-grid hybrid core was proposed to enhance the structural performance of composite sandwich panels. However, important gaps remain in calculating the structural performance of the composite sandwich panels. In this paper, an equivalent stiffness model was proposed to analytically estimate the stiffness matrix of composite sandwich panels with honeycomb-grid hybrid core. The reliability and accuracy of the equivalent stiffness model were verified by experimental measurements from three-point bending tests. Furthermore, the effects of face-sheet thickness, core height, grid spacing, rib width and material properties on structural stiffness were investigated for the design of sandwich structures with hybrid core. The parameter studies demonstrated that core height had the most significant influence on the specific bending stiffness, while grid spacing was most important for specific in-plane stiffness of sandwich panels with carbon-fiber grid. Moreover, using carbon-fiber grid, although increases manufacturing cost, could further enhance the specific stiffness.