Title: A Failure Criteria for Honeycomb Core

Authors: Patrick O'Callaghan

DOI:

Abstract: Honeycomb sandwich structures have widespread use in structural engineering due to their high specific strength and high specific stiffness. Honeycomb core that reacts transverse shear load in sandwich structures can fail either under static or fatigue loading. This paper examines how to predict static and fatigue loading under multiaxial loading and how to determine the critical angle for loading of the core. This is supported by testing performed on specimens manufactured with three different aramid fabric cores dipped in phenolic resins. The specimens include two hexagonal cores of different densities and one over expanded core. The results of the testing used to substantiate the conclusions are presented. This paper describes the results of tests and analysis performed to determine failure criteria for representative phenolic coated paper cores used in aircraft structures. These tests involve both static and fatigue tests carried out in the material L and W direction as well as at intermediate angles. Static and fatigue testing was performed using the ASTM C273 test protocol. Static testing was performed at room temperature, at -100°F and on saturated specimens at 120°F. This testing was performed in the ribbon and normal to the ribbon (L and W) directions and points in between. Fatigue testing was performed on representative core at room temperature. The results of this testing are presented and failure criteria for the representative cores under biaxial loading presented. Using the results from these tests, a failure criterion is proposed for these cores. It is shown that the minimum shear strength is lower than either the design L or W directions. The minimum shear strength is determined for the cores examined. One explanation for the reported results is given, based on FE (finite element) analysis performed by the European Space Agency and recommendations made for additional research.

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Conference: SAMPE 2026

Publication Date: 2026/04/27

SKU: 171

Pages: 17

Price: $34.00