Panel Structure vs. Solid Rod Structure

[blixxa]

Hi Everyone,

I have a question about panel vs. solid rod structures.

Assume a two cubes of equal dimension and weight.

Cube 1 is made of panels, ie. a hollow cube.

Cube 2 is made with solid rod

Material is linear elastic


Which would be stiffer?

I think the panel structure would be the stiffer structure because each panel is supported by another resisting bending. In the rod structure, the rod is only supported at the ends.

Any input would be greatly appreciated

Cheers.

 

[blixxa]

Futher to this,

I have forgotten a lot from my engineering degree,

How would you work out the deformation of the cube under a vertical load?

I think I can do it for the rod structure but not the panel structure.

Cheers

 

[xxChrisxx]

As with all things, it depends on the exact materiel and construction.

It appears you are describing a monocoque vs spaceframe. The stressed skin has the potential to have much higher stiffness to weight ratio.
If it's just a box, with 12 structural members along the edges, the proper hollow box will be stiffer. This is because a cube would need to be cross braced.The 'resisting bending' idea is the right concept but wrong direction. For a stiff structure you ideally want no member experiencing any bending, so any 'bending' is eventually taken by a member in tension or compression.