Removal of pressure loading - panel sizing vs substructure

[MattA]

I gather that the recommendation is to comment out pressure loading for flat panels, prior to running an FEA, and then uncomment in order to import the pressure loads into HS, and let HS take care of pressure on panels. (ref https://hypersizer.com/forum/index.php/topic,357.0.html)

How does this work (if at all) for carrying that pressure loading into the substructure.  For instance, with a wing structure, if you remove pressure loading on the wingbox, the wing is then unloaded, so spars etc will not have load in them in order to size them.

Is the solution to convert pressure loading on the panel to nodal loading at the panel edge in order to capture the substructure loading due to pressure?  Or is there a better way of doing this within Hypersizer?

Thanks,

Matt

[Stephen]

Hi Matt,

I think that the post you referenced might be a bit out of date with how we typically recommend users handle this in the more recent versions of HyperSizer.

Our best practice in general is to use the "Zero Out FEA Moments" option on the sizing form for flat panels with FEM pressure loads, and enable "Panel Pressure" in the same section. This will ignore the moments in the results file, and turn on our offline pressure calculation to determine bending moments and transverse shear loads due to pressure on a flat panel. This offline pressure calculation reads the PLOAD cards in your FEM to determine the pressure applied.

This process usually works pretty well for aerospace, since most acreage panels see relatively small bending moments due to mechanical loading, so ignoring those from the FEM and calculating what they should be due to pressure is usually fine. Note that we don't recommend this for curved panels, as it would generally be very conservative to treat it as flat, and FEA does a pretty good job of getting hoop tension, bending moments, and transverse shear for curved panels with a reasonably well-refined mesh.

Thanks,
Stephen

[MattA]

That makes sense!  Thank you Stephen.