Stiffening a Corrugated Sheet

[Doodler3D]

Hi,

What are some quick hand calcs to estimate the stiffening required for a corrugated panel? Traditionally, the general approach is to rib the hell out of the structure based on tribal knowledge, but I was hoping for a nudge in the right direction to optimize moment values for the stiffeners since the application is deflection-limited rather than stress. The 10' long, 1/4" thick panel is the base of a screw feeder. C/S for reference.

 

[le99]

You should ask the supplier for the manufacturer-supplied table for strength and deflection based on the orientation of the corrugation and span length.

 

[Doodler3D]

Overseas supplier (close to the installation site) is not willing to share design calcs, except that deflections are limited to 1/8". Currently exploring local fabricators to get this done, hoping that some basic reference calcs will help them out.

 

[le99]

See whether this article helps.

https://www.nj.gov/transportation/eng/structeval/pdf/LFRCorrugatedMetal.pdf

 

[SlideRuleEra]

What are some quick hand calcs to estimate the stiffening required for a corrugated panel?

Assuming the corrugated sheets are used flat (like your sketch), take the moment of inertia (I) of a stiffener (ignore the structural properties of the corrugated sheet) to calculate deflection. This will give a conservative answer. Each stiffener will have a tributary loading area based on stiffener spacing.

Four PSI (576 lb/ft[sup]2[/sup]) is significant loading. Don't be surprised if the stiffeners seem to be ridiculously large for 1/8" deflection over a long span.

 

[centondollar]

Use an orthotropic Kirchoff plate model that smears corrugation stiffness into the plate stiffness (google it; should be found in plate theory textbooks), suitable displacement trial function and Ritz method to solve for the corrugated plate deflection and internal forces.

 

[Doodler3D]

Centondollar, thank you for that, Timoshenko's Plate book is on my desk and I'm assuming you are eluding to sections 20 onward.

SlideRuleEra, you are correct, the stiffeners are rather thick.

 

[3DDave]

alluding, just FYI.

 

[3DDave]

Is there some reason it has to be corrugated? Seems like an unnecessary constraint. I'd make a box section with internal ribs - cut some slots to key with vertical strips and fusion weld. The stiffness:cost ratio is easily better if stiffness is paramount which is why this sort of construction is used most everywhere and simple corrugation is used when stiffness isn't so important.

 

[Doodler3D]

Dave, Its the base of a screw extruder and tight tolerances are to be maintained for the screw.
BTW, I put on my dunce cap for mixing words.

 

[3DDave]

I'm stuck then. I see no use for a corrugated part in a screw extruder so it must be a special design and I have no idea where that part could be.