Weighted links - co-linear points

[346gnu]

Hi,

Why can't we have co-linear points on the independent side of a weighted link?

It's easy to get the warning message

'The independent geometric entities must not form co-linear points'

by selecting any 2 points for the dependent side (must form a straight line),

This is CREO2.0 M030 (I don't have any other versions with me to check)

Thanks

Thanks

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[echan]

Hi Charles:

The independent side of a weighted link can't have collinear geometries (points or curves) because mathematically, the displacements and rotations of the dependent point are tied to the displacements of the independent geometries. If the geometries of the independent side are collinear, one or more of the dofs on the dependent point won't be tied correctly.

Eduardo

[346gnu]

Eduardo,

I don't understand yet, Can you explain a bit more?

Thanks

[TadDoxsee]

Hi Charles,

Eduardo is on vacation, so I'll answer for him.

The motion of the independent side of a weighted link must be able to define a rigid body motion. The motion of just two points (or a set of colinear points) cannot define the rotation about an axis passing through those points. Therefore, the independent side of a weighted link must consist of at least three non-colinear points.

Tad Doxsee

PTC

[346gnu]

got it, Thanks