Hydrostatic Pressure To Wall

[n.s.kouros]

Hey there! 

I have a huge confusion for like 3 days now. I have a part designed in mm. Assume it is a wall. All units in mm.

I want to check if it can withstand a pressure of a liquid. Assume sea water.

After calculations the pressure applied needs to be 150 kN/m^2. 

I go to the FEA Environment in Inventor, apply my fixed constraints and press the Pressure Button. MPa appears. 

1Pascal = 1N/m^2. 

150kN/m^2 = 0.150 MPa.     (MPa = MN/m^2)

but my design is at mm. 

What value should I input in the MPa box. Does the program recognize the mm and convert or should I convert MN/m^2 --->MN/mm^2.

Thanks!! 🙂 

[JDMather]

Attach your file(s) here.

Is this a submerged vessel or is it a vessel containing liquid?

In nearly all Inventor dialogs you can enter equation and then if you hit Tab you will see the converted results.

If the equation is valid - it will turn black.  If it is not valid - it will be red.

[blair]

Nastran InCad will do hydrostatic out of the box. For the standard FEA within Inventor, you would need to use the Split-Face command to create strips along the "wall" to apply a predetermined force to each band along the wall as the load will increase down the wall.

[JDMather · Accepted solution]

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@blair wrote:

... you would need to use the Split-Face command to create strips along the "wall" to apply a predetermined force to each band along the wall as the load will increase down the wall.

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[n.s.kouros]

These are pretty much known. I have seen the video, thank you very much. 

The wall examined is Mild Steel Plate th=11mm. 

It is the one of 5 sides of a container. 

My question is on the units. I am designing always in mm, and the Pressure units include area in the denominator. F/A.

I am worried if I type 150 (whatever) / m^2 in inventor, while having the model in mm, the program misunderstands and place this force over mm, instead of m, causing very high stresses. 

@Anonymous: You are correct. The proper study to hydrostatic is to go from lower values (on top of tank) to higher, but when you design with regualations, you take the worst case scenario (higher force acting in low), as acting everywhere. 

[JDMather · Accepted solution]

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@n.s.kouros wrote:

I am worried if I type 150 (whatever) / m^2 in inventor, while having the model in mm, the program misunderstands and place this force over mm, instead of m, causing very high stresses. 

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Inventor is "units aware", it will take care of this for you.

If you don't trust it (trust but verify) you can very easily set up a simple verification study.

[n.s.kouros]

I did a new simpler model, designing in m, instead of mm, so to check about the input dimensions. 

Seems like, inventor does the job for us! 

Thanks all, for your time!