NASTRAN Modelling of Honeycomb Sandwich Panels Subjected to Picture Frame Shear

The objective of this study was to model honey­comb sandwich panels under in-plane shear load­ing. It was desired to develop a method using relatively simple and easy to generate models, which would accurately represent test panels under load in a picture frame fixture. As part of this method, a fairly detailed model of the test fixture was made. It included the external boundary conditions and forces as well as the panel attach­ment bolts. Several models were made, represent­ing different configurations of the sandwich panel. These were easily interchanged in the frame model, thereby maintaining an accurate and consistent representation of the panel boundary conditions from run to run. These various finite element models were generated in support of an ongoing Boeing Model 360 damage tolerance study. The experimental portion of this study subjected a number of composite sandwich panels to in-plane shear loading in a picture frame fixture. The test specimens, representative of typical Model 360 fuselage structure, included panels with woven graphite facesheets or woven Kevlar facesheets over Nomex honeycomb core in one of two densi­ties. An existing picture frame fixture was used for the testing phase to allow for direct comparison with previous phases of the experimental work. The model results and the experimental data were generally found to be in good agreement. In addition, the finite element analysis highlighted certain drawbacks of the test fixture design, reflecting the results of earlier studies found in the literature. This paper describes the modelling process and compares the finite element results with test data.