What is the typical construction of a sandwich panel and what benefit does it provide?

• A. A honeycomb core between two facing sheets; low density, large bending stiffness
• B. A solid metal plate with high density
• C. A single thick polymer layer
• D. Four plies stacked with 0/45/0/45 degrees

Answer: (A)

Sandwich panels achieve high bending stiffness with minimal weight by placing thin, stiff facing sheets apart with a lightweight core. The separation of the faces increases the moment of inertia, so the panel resists bending much more strongly for a given material, while the core provides shear support to keep the faces from bulging or sliding relative to each other.

A honeycomb core between two facing sheets is a classic construction because it combines very low density with enough thickness and structural integrity to transfer shear between the faces. The facing sheets carry the primary bending stresses, while the core handles shear and helps keep the skins aligned, giving a large bending stiffness without a lot of added weight. This arrangement is especially advantageous for applications where you need rigid panels but want to minimize weight, such as in aerospace, automotive, or marine components.

Other options would either be much heavier (a solid high-density plate) or not provide the same out-of-plane stiffness per unit weight (a single thick polymer layer or a laminate without a thick core).