Failure mode maps for honeycomb sandwich panels

Failure modes for sandwich beams of GFRP laminate skins and Nomex honeycomb core are investigated. Theoretical models using honeycomb mechanics and cl assical beam theory are described. A failure mode map for loading under 3-p oint bending is constructed, showing the dependence of failure mode and loa d on the ratio of skin thickness to span length and honeycomb relative dens ity. Beam specimens are tested in 3-point bending. The experimental data ag ree satisfactorily with the theoretical predictions. The effect of honeycom b direction is also examined. The concept of a failure mode map is extended to give a useful design tool for sandwich panels manufacturers and their c ustomers. (C) 1999 Elsevier Science Ltd. All rights reserved.