Failed round: self intersecting geometry

[tbraxton]

Creo 7.09; I am not able to provide the model for inspection.

Can anyone offer any insight into how to get this round to regenerate? The solid surfaces involved are all planar or cylindrical. I am hoping someone can suggest what to look for when this is happening.

The model has no geometry checks and has absolute accuracy set. Rolling ball and spinal options fail, variable round fails. Surface round will regenerate but cannot be solidified and has transitions that are not consistent with the solid geometry needed. The surface round produces the same error when attempting to solidify the quilt.

You can see below in the image that it is curling back on itself and not following the edge selected for round to be applied to.

[MartinHanak]

Hi,

please publish also picture of surface round. What happens when you use smaller value eg. 0.25 ?

[tbraxton]

The previous picture posted is using the surface option in the round. The yellow spiral is the surface created by the feature. I have tried values as low as 0.05 mm radius with the same issue.

[kdirth]

I appears Creo is having problems with following the tangency.  Have you tried making a second set beyond the tangency for Creo to follow.

[tbraxton]

I determined the root cause of this. It is related to another round feature upstream in the order. If I change the order of the "problem" round feature, then I can get this one to regenerate. The problem round feature does not intersect this round that fails to regenerate which is odd. It does intersect one of the planar surfaces that is a reference to this failed round.

This problem feature is somehow causing Creo to not regenerate two downstream rounds properly. Unusual behavior. PTC support will probably argue it is unique to this model. I think otherwise but do not have the time to prove them wrong on that at this time.

I have "fixed" this by reordering the problem round to after the failed regeneration rounds and the model regenerates fully without geometry checks.

[tbraxton · Accepted solution]

The problem is caused by a surface intersection in the solid. It creates an unstable geometry condition with the surfaces in the geometry kernel but does not throw a geometry check. Any children of this surface intersection result can be unstable. Unpredictable regeneration without any feature or geometry errors generated.

This is the area that is causing the issue. Note that it does not interface directly with the rounds that are failing as a result. Which are outside the view here. The failed rounds reference one of the surfaces (planar) involved in this intersection of solid geometry.

Zoomed in on the corners above.

Modifying the surface intersection to that shown below results in all features regenerating without any errors.