Hi,

I'm sizing a wing structure with corrugated panels. I use HyperFEA, and after a set of iterations, I update all the bounds, then re-run HyperFEA. When I update the bounds (based on the found result and Margin of safety), for some components, I get 'INVLD GEOM'.

I found out that I get rid of it if I increase the Y span panel buckling. So, I guess this INVLD GEOM is due to the violation of the Geometry Rule 40, i.e. 'Panel Width to Stiffener Spacing [Min # of stiffeners]'. Is that right ? (note that the analysis finishes without any error).

Therefore, I would like to know what would be the best (realistic & clever) way to solve this issue, knowing that I can't increase the panel buckling, since it is fixed by the position of ribs/spars ?

Should I just impose a maximum value when I'm updating the bounds, so that the stiffener spacing is not higher than 1/3rd of the panel buckling (to get at least 3 stiffeners) ?

If yes, I should also impose maximum values for other properties since this spacing should also be higher than the sum of all the parts between two stiffeners (e.g. flanges)... And therefore, what should I do if all these upper bounds are hit by HyperSizer during the analysis ?

PS: I also had a similar problem when sizing uniaxial stiffened panels.

Thanks for your help,

Regards