How do I calculate the moment of inertia of a hollow hexagon. The hexagon is 0.87" flat to flat. The wall thickness is 0.200" thick.

I am trying to see if the hollow hex will be better then a solid hex in a beam calculation.

Material is 6063 T5 alluminum

Rule:

The moment of inertia (MI) for a hexagon is given on the website -

http://en.wikipedia.org/wiki/List_o...of_inertia

For a hollow hexagonal beam you need to subtract the hollow space from the outer shape.

Since you have a lower MI the hollow will not be as stiff as the solid beam, but if you use stiffness or strength to weight ratio the hollow will have a higher value.

Niel Leon
Engineering.com