Which of the following materials is not listed as a facing or core material for bonded honeycomb structures?

• A. Carbon fiber
• B. Stainless steel
• C. Glass
• D. Nylon

Answer: (A)

Bonded honeycomb panels rely on two facing sheets with a lightweight honeycomb core between them. The materials used for cores and faces are chosen for stiffness, weight, and environmental resistance. In the typical listings for facing or core materials, stainless steel, glass, and nylon appear as core or core-like materials because they can form or support the honeycomb structure in various environments. Carbon fiber, while widely used for face sheets in many composite skins, is not normally listed as a standard core or facing material for bonded honeycomb structures in the reference being used. It’s more commonly seen as the skin material in a carbon fiber reinforced sandwich rather than as part of the honeycomb core/facing combination described here. Therefore, carbon fiber is the best choice for not being listed in that context.