My latest project contains a retractable roof (www.villo.nl
Now it is an interesting question what the z-displacement is just before it is supported by the mast. The roof will be made of an aluminum frame covered with aluminum sheeting.
First I did a Scan and Solve test as if it is a solid piece of aluminum and specified a scalar force for the gravity. Then the question raised; what's the difference with a hollow structure made of frames, stiffeners and sheeting? So I set up a simple test to find out.
To keep it simple I modeled a simplified geometry both hollow and solid. One constraint of SNS is however that I can only select a single solid. When modeling the structure, several solids are created which are not connected. I tackled this issue by adding a small rectangular pipe connecting the outer shell with inner cavities. Thus creating an open cell structure.
Furthermore I didn't use the gravity option but simply added a scalar load representing gravity.
The results for the z-displacement were:
- Solid: -9.5 mm
- Hollow structure: -19 mm
This seems a big difference, but wall thicknesses are small and I only used one internal stiffener.
Attached is the test file.
As I am not a specialist in FEM, I am interested in your comments.Please find a full report about Villo roof analysis over here