IntermediateTopic 50 of 100Materials & Chemical
Sandwich structures
Light cores between stiff skins give high bending stiffness.
In depth
Two thin stiff faces separated by a light thick core (foam, honeycomb, balsa) give very high bending stiffness and strength per weight, as I increases with core thickness. Failure modes: face yielding, wrinkling, core shear, indentation, debonding.
Key points
- Core shear stress
- Panel bending stiffness D≈E_f t d²/2
- Moisture ingress in honeycomb
ExampleAircraft floors and wind-turbine blades use sandwich panels.
Sandwich structures give high bending stiffness with low weight, which is why they are used in aircraft, boats and wind turbine blades.
What is Sandwich structures?
Light cores between stiff skins give high bending stiffness.
Why is it important to understand sandwich structures?
Sandwich structures give high bending stiffness with low weight, which is why they are used in aircraft, boats and wind turbine blades.
Why does a sandwich panel stiffen so much?
The skins carry bending stress far from the neutral axis, and the core keeps the skins apart, which raises the second moment of area.
What is the core material for?
It resists shear and holds the skins apart, so the core must be stiff enough in shear and stable under the operating conditions.
How is Sandwich structures used in practice?
Typical applications include building a lightweight floor panel with a honeycomb core, making a boat hull with a foam core between two composite skins and designing a wind turbine blade shell with a sandwich panel.
What should I learn before Sandwich structures?
Study "Laminates" first (topic 49 of 100 in Materials & Chemical). It covers the groundwork this topic builds on.
What are the key points of Sandwich structures?
Core shear stress. Panel bending stiffness D≈E_f t d²/2. Moisture ingress in honeycomb.
Can you give an example of Sandwich structures?
Aircraft floors and wind-turbine blades use sandwich panels.
What comes after Sandwich structures?
The next topic is "Biomaterials", which builds directly on this one.
How difficult is Sandwich structures?
It is classed as Intermediate in Materials & Chemical (topic 50 of 100). It is an intermediate topic. Work through the beginner topics in Materials & Chemical first.