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saspinall1-Visitor
1-Visitor
September 8, 2016
Question

Volume of Free Space in Assembly

  • September 8, 2016
  • 5 replies
  • 5909 views

Hello

Does anyone know of a way to determine the volume of the free space left inside an assembly.  We design connectors which are constructed of several sub components/assemblies.  To determine the volume of oil required to fill the connector, we have made a solid component, which is then assembled into the connector, then used the Component > Cutout feature to individually cutout each connector component which ,when every sub component/assy has been used to cut away the solid component, will leave a component which can the determine the volume with.

Surely there must be a quicker and easier way than this, in this day and age.  Someone thought that they has seen a similar thing done in Behavioural Modelling, but I can't find anything to view etc.

Does anyone have any good suggestions of how to achieve this...and to make it associative, like adding the mass properties to the footer so that the mass is always calculated each time a feature is modified/added.

Thanks in advance

Stuart


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5 replies

D
dschenken1-Visitor
1-Visitor
September 9, 2016

None so far. It's not as easy a problem to solve as one imagines because while it is easy to see if a point is inside a solid it is harder to determine if a point is both inside a solid boundary but outside the solid.

If a solid is tesselated (smooth surface replaced by triangles, as required for OpenGL)  then each triangle can be projected onto a plane and that projection used to calculate the volume between it and the original one. If the triangle faces up, the volume is added to all the others; if the triangle faces towards the plane, the volume is subtracted.

Since Creo can guarantee the triangles face outward from the solid, this method works to determine the volume inside a solid.

But it can't tell a void in the solid from a hollow.

It seems pretty obvious for a balloon, but what about a bucket?

Behavioral modeling is good for goal seeking. If there is a volume required than an input to control it, Behavioral Modeling can close the loop.

Cutout is the easy way.

S
saspinall1-VisitorAuthor
1-Visitor
September 9, 2016

Thanks David....answer as i thought...cutout only real answer

Stu

D
danderson1-Visitor
1-Visitor
September 9, 2016

What about inserting a mass properties feature at a point in the connector model when the connectors completely solid to get initial volume and then add another mass property feature at the end of the modle tree to get volume of the connector hollowed out. Subtract this with a relation and feed to a pameter. Not this with simmalar volumes for all of the other connector pieces can be rolled up at the assembly level in a repeat region to give you the oli volume.

Hope this helps,

Don Anderson

S
saspinall1-VisitorAuthor
1-Visitor
September 9, 2016

Thanks Don

Interesting suggestion, it would work, although I think needs to be setup at initial design stage of the component parts, maybe a bit more work to do if trying to accomplish after the Xth revision of the assembly.

Stu

J
jthomas-21-Visitor
1-Visitor
September 9, 2016

I don't know if this is any easier but here is a method I use for finding oil volume in brake assemblies.  Assemble a new component in the assembly which will be the oil volume.  In the assembly select the oil bounding surfaces of the first component and hit CTRL+C to copy them.  Activate the oil volume component in the model tree and hit CTRL+V to paste.  Activate the assembly again.  Individually do this for each component in the assembly.  After all oil bounding surfaces have been copied to the oil volume component merge the surfaces then solidify.  The oil volume can then be analyzed.

J
JonathanHodgson13-Aquamarine
13-Aquamarine
September 12, 2016

A possible speed-up for a one-time calculation is to make a shrinkwrap of the assembly and cut that away from the volume, rather than cutting each component individually.  Don't know whether this can be made parametric though - you may have to do it each time.

    H
    habdul1-Visitor
    1-Visitor
    September 19, 2016

    Another way is using simp reps. In each connector, you'd have a simp rep named "no_cutout" (for example) where the cutout feature is excluded. In the assembly, you'd have a simp rep also "no_cutouts" (for example) where all connector parts are substituted by their respective "no_cutout" rep. Then you can get the mass for the master rep (as is) and the "no_cutouts" rep (complete solid) in the assembly and subtract the results.

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