A COMPARISON OF HONEYCOMB-CORE AND FOAM-CORE CARBON-FIBER EPOXY SANDWICH PANELS

Cellular core sandwich panels of carbon-fibre/epoxy fabric laminate skins, simulating the construction of an aircraft flap, were cured and bonded in a single-step autoclave operation. Nomex honeycomb and Rohacell WF foam of different densities were employed as the core material. The panels were examined to identify voids in the laminate skins and cell collapse and coalescence in the foam core. Test-pieces were subjected to low-energy impact and the induced damage was determined by ultrasonic C-scan. The maximum damage area in the face-skin was comparable to the projectile cross-sectional area. Residual compressive capacity showed an asymptotic decrease with increasing impact levels, most panels gave similar values but the modes of failure were different depending on the type of core. The resistance of the separate panel components to full impact puncture was assessed using instrumented impact load-deflection traces. © 1990.