Analysis methodology for the assessment of unvented honeycomb sandwich structures subject to in-plane and pressure loads

As an aircraft or spacecraft ascends, the atmospheric pressure drops. If the internal pressure is not released, a pressure differential develops on the facesheet. With an in-plane load from vehicle acceleration as well, the pressure and in-plane load may cause failure. Vented sandwich structures are strongly preferred since they release the internal pressure; however, special cases still require an unvented design. This paper provides an analysis and test methodology for unvented sandwich structures. Parametric studies of facesheet-core debonding and buckling were conducted via finite element analysis, considering geometric, material, and load parameters. Design curves based on the key nondimensional parameters were tuned to the data from the parametric study, providing a tool to predict facesheet-core debond failure. Examples of how to use the design curves in practical applications are provided.