The in-plane stiffnesses of a honeycomb core including the thickness effect

Summary The subject of the consideration is the contribution of a regular honeycomb core to the effective in-plane stiffnesses of a sandwich structure. Due to the coupling of the core displacements with those of the sandwich face sheets, the stiffness contribution of the core is not proportional to its total thickness, as could be expected. The corresponding thickness effect is investigated by means of an appropriate closed-form approach. In doing so, the total elastic core strain energy is calculated based on an adequately chosen displacement representation. Further on, the resultant effective stiffnesses are derived as a function of the total core thickness. A comparative computation of the effective stiffnesses by finite element analysis gives good agreement. Received 5 August 1997; accepted for publication 23 October 1997