Pressure load is in the wrong direction

[shoyt4LEEN]

I am trying to preform a FEA analysis on a shelf assembly. The actual shelf itself is a sheet metal part so I had to use the "Find Thin Bodies" to convert the part to a shell in order to simulate. After that the pressure load comes up with an error, so I edit it and reapply it to the top surface of my shelf. At this point it only lets me select the bottom surface of the shelf, not the top and there is to option to switch directions for a pressure loading. 

Is there any way to apply the pressure to the top surface of the shelf instead of the bottom?

Pretty lost, any help would be appreciated. 

@Anonymous 

[JDMather · Accepted solution]

I do not see an Pressure Load (or any analysis for that matter) in the assembly that you Attached?

The logical question, what if you change the direction with a minus (-) sign on the value?

Q2. If you apply a Pressure of 1psi how much Force are you applying?

[shoyt4LEEN]

Yep. Definitely that simple.

Is my thinking correct in if I wanted to find the force that 1 psi would apply to the shelf, I would need to find the surface area of the top of the shelf, then multiply that by 1 psi, to find the force? This would be the same logic for any pressure applied on any geometry, find the area of the face the pressure is applied to and multiply that area by the pressure to find the force? 

Much appreciated. 

[JDMather]

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@shoyt4LEEN wrote:

Is my thinking correct in if I wanted to find the force that 1 psi would apply to the shelf, I would need to find the surface area of the top of the shelf, then multiply that by 1 psi, to find the force?

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Yes.

Not sure why you were using Pressure instead of Force in this case.