Degree of freedom analysis

[moto748]

In Inventor 2011. Such a good idea, you can check after completing an assembly/weldment that all parts are correctly constrained, but is it just me, or is it a bit rubbish? It appears to give a lot of false negatives, and often seems to say that parts are under-constrained when they are not.

For one thing, it seems unable to cope with patterns. I could live with that, but it's not just patterns. On one weldment I created recently in particular, it claimed nearly every part was under-constrained. One reason I can think of is that the bulk of this weldment was created in Frame Generator, with additional parts added in later with conventional constraints.

Any comments, guys?

[JDMather]

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@moto748 wrote:

Any comments, guys?

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I know when my parts are properly constrained without asking the software if I am doing my job.

[moto748]

And a Happy Christmas to you too, JD!

[JDMather]

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@moto748 wrote:

And a Happy Christmas to you too, JD!

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I suspect that many of the "automatic" tools they put in Inventor are "pretty wrapped presents" for canned VAR presentations that no one (with experience) actually tries to use in production.  Autodesk isn't alone in this, I see the same kind of thing in other CAD SoftWare applications.

If you really want this to work I recommend you post actual examples to illustrate your point and participate in Beta http://beta.autodesk.com keyword Brunel

also,

http://usa.autodesk.com/adsk/servlet/index?siteID=123112&id=1109794

[Julianortegaic]

an initial componetn in an assambly have 6 DOF, how could i do to constrain a degree of freedom, I need that my component only have 5 DOF ( 3 rotational and 2 translational).

Thanks

[JDMather]

Attach your assembly here if you can't figure it out.

If you Mate a point on the part to one of the origin planes (or a planar face of another part)  the point cannot leave the plane but can translate in 2 DOF of the plane.  The rotational 3 DOF are retained.

[Julianortegaic]

I havent the assembly in this moment, so i cant attach it, I will do it later.

the thing that i have to do is don't let that the component will have vertical displacement ( axis Z) but I need that the component could rotate around the 3 axis and could move it in X and Y plane.  ¿is that possible? 

[JDMather]

Check attached.

[Julianortegaic]

Hi, I saw the Attached File and ist exactly waht I need, could you helpme to explain how a made a Mate with the component and a plane, I am attaching the assembly , there is 4 frame conected to a "joints" with a mate and tangent constrain, but I need that the joints stay in the same plane that be the grounded one, but able to rotate in the 3 axis and move in the other 2 planes.

Thanks 

[JDMather]

Did you figure this out?

[AndyWallace]

Moto748, I continue to see false positves also. Turning on Degrees of Freedom in the View...Visibility pane does the same thing. Here, I've got a simple test assembly with a screw that is in reality fully constrained. I cannot move it yet DOF analysis shows it can move up and down. Time and time again I've been fooled.

JD, your point about doing your job and not needing the tool is true. But behavior like this in a tool, when you may need to depend on it, is unpleasant.

Here's a screencap. Inventor 2014.

I know Autodesk probably can't copy the Solidwork idea of showing (-)PART in the tree when a part is not fully mated/constrained, but it sure would be nice.

Andy