Which materials are used in facings and core materials for bonded honeycomb structures?

In bonded honeycomb structures, the core materials typically comprise lightweight and strong materials that offer excellent strength-to-weight ratios, which is crucial in aerospace applications. Stainless steel, titanium, magnesium, and glass are all suitable for use in facings and cores because they provide the necessary mechanical properties and can withstand various environmental challenges.

Stainless steel and titanium are particularly notable for their high strength and corrosion resistance, making them ideal for structural components that need to endure significant stress and fatigue. Magnesium, being one of the lightest structural metals, contributes to reducing the overall weight of the assembly, which is a critical factor in aviation. Glass, often used in the form of fiberglass, enhances the toughness and rigidity of the honeycomb structure.

While other materials listed in the other choices have specific applications, they do not align as closely with the requirements for facings and cores in bonded honeycomb structures. For instance, wood and cardboard are not suitable due to their weight and structural properties in this context, while rubber and copper do not provide the necessary structural integrity and corrosion resistance.