Any Idea How to Model "liquid" in Pro/E to determine CG 1

[sundevil98]

I'm wondering if there's an easy way to model some "liquid" in Pro/E.

For example, say I am modeling an airplane. Within the hull, there are a lot of nooks and crannies filled with some small assemblies. I'd like to be able to fill the body full of "fuel" so that it fills up all the empty space. Is there an easy way to do this?

Likewise, it'd be great if I could have the solid fuel model behave like a liquid in order to see how the pitch of the airplane and the sloshing of the fuel affects the CG of the airplane.

Is this at all possible? Does anyone know of any other sort of tool that I could use to accomplish this?

Thanks

 

[Hayden]

I can help with half of your question.

To model the fuel as if it were solid you could make a quilt of the inner surfaces of the tank and use Create/Protrusion/Use quilt. If you wanted to be clever you could put in a planar surface to indicate the fill level of the tank and include this as the top surface of your quilt.

To do this, Create a new part and with no geometry (fuel.prt) and assemble into your airplane. Usee modify/mod part (pick fuel.prt)/feature/surface/new/copy. Pick the inside surfaces of the fuel tank.

Open fuel.prt and use quilt to create a solid.

I hope this makes sense, some of the menu picks may not be spot on though. I used to use this for pouring concrete around reinforcing bar so I know it works.

Hayden

 

[noppenbd]

If you want to model the fuel tanks when they are not completely full, you will need to model a top surface for the fuel. You can do this by creating a global coordinate system which is rotated to reflect the pitch of the aircraft (Insert/Datum/Coord Sys/Offset). Then create a datum curve which goes from the top to the bottom of your tank. Create a Datum Point on this curve by length ratio. This will allow you to set the percentage of fill for your tank. Then create a datum plane which is parallel to your new coord sys and passes through the point. Create the datum curve and point for each tank. If you sketch a big flat surface on each of these planes and merge it with your tank inner surfaces, it will accurately reflect your partially full tanks with a top surface which will follow the new coord sys. I hope this helps!

 

[peglor]

The cut out option from advanced utilities will allow you to make a large solid which takes up the whole area of the fuel tank and then cut out the other parts which intersect this area where fuel is stored. This will leave you with a solid part modelling the area taken up by the fuel. Cutting the top off the shape you're left with, using the assembly as a datum from which the fuel level is measured will allow you to calculate the shape of the fuel for various fuel levels.

Changing the angle of the cut allows you to model the fuel position as the plane tilts during take-off/flight. Defining a three point plane using points referenced from datum curves defined by angles relative to the horizontal is probably the easiest way to make a datum to use to locate the cut.

setting analysis features to modify this level to give a certain volume of fuel can also be done if that is something that would be useful as the volume of the part can be easily calculated by ProE.

Hope this helps.

 

[sundevil98]

Thanks for all the replies. I'll give the cut out feature a try... I've never used that.

Peglor, are you saying it's possible to set a feature that will automatically set the cut so that there's only a certain volume of my fuel model? If that's the case, that'd be most helpful... How can I go about doing that?

 

[peglor]

I've built a very basic model with pictures at:

http://www.csn.ul.ie/~ceason/proeng/.

You'll note that the wing has dents in it. When the wing shape is cut out of the fuel there will be volumes left outside the boundary of the wing if there is no volume of another part intersecting the fuel part. These unfortunately have to be cut out manually. This is where using quilts of the inside of the tank for the cut could be more useful.

http://www.csn.ul.ie/~ceason/proeng/Wing_fuel_asm.jpg

shows the datum curves with points at their ends used to define the fuel angle. The fuel level is made by creating a plane offset from the fuel angle plane from which a cut is extruded.

An analysis feature can be set up in the fuel part to measure the volume of the part.

http://www.csn.ul.ie/~ceason/proeng/Analysis_feature.jpg

Volumes of individual parts can't be calculated in assembly mode as far as I can see.

By creating the cut using a plane generated on the fly offset from the Fuel angle plane (You'll need a plane normal to this to use as a orientation reference for the sketcher) you now have a dimension which you can vary in a feasibility study which varies the depth of the cut

http://www.csn.ul.ie/~ceason/proeng/Feasibility.jpg.

Hope this answers a few questions.

 

[sundevil98]

Very Helpful!!!

Thanks so much for showing me that. I've never used the Optimization/Feasibility function before.

That's exactly what I need. This is going to help me do some mass properties studies. Now instead of guessing and interpolating values of the dimensions for the cuts, I can pretty much do it in no time!

Thanks for all the help!