Surfacing Help: Style Surface Boundary Conditions

Forum|Forum|11 years ago
August 21, 2014
2 replies
8899 views

I've been working more on this shroud (http://communities.ptc.com/thread/56128) and now I'm trying to figure out how to control the boundary conditions of a style surface.

The boundary conditions at my edges where I have control curves are good (i.e. they are curvature continuous and normal to the plane, but in between control curves the surface does not keep that condition.

This becomes obvious when I thicken the surface with a normal offset. If the surface were normal, the part of the edge would be coincident with the horizontal red line (surface edge).

All of my edged except for those on the inner circle have edge control arrows. Why don't the arcs?

Surfacing

Best answer by Dan_Harlan

Ok, making progress.

First thing I found (and my first mistake) was thinking that the wireframe curves would be sufficient for defining the curvature was wrong.

Second, I found that the surfaces (even if the part won't actually have those physical surfaces) adjacent to the smooth (G2) surfaces must be defined. In my case, these were the two cylindrical surfaces that represent the final smooth airflow direction and the 'rim' type surfaces perpendicular to the airflow.

With those surfaces, I could then go and define the end points of my styles curves to be Continous.

Then I could go and make connections between the style surfaces and my reference continuos surfaces by selecting the broken line indicators.

If more than one surface was possible, then you would get a prompt like this (asking if the red surface was the correct surface to connect to).

Once those connections were made, then I could set those connections to be surface continous (they defaulted to tangent).

Still have some investigation to do and cleanup, but this looks like a solid solution.

J

James62

1-Visitor

Hi,

Use cylindrical surface instead of the arc curve to be able to set the boundary condition for the compound surface you are making.

If your curves don't have curvature continuous connections with the adjanced surfaces then the surface you are making won't be curvature continuous either.

D

Dan_Harlan

Author

1-Visitor

Not quite sure what you are meaning. I've attached the file so you can take a look.

The center circle is just that, a circle. The guide curves are style curves; planar, 3rd order, two points only with end point conditions of either horizontal or vertical.

1_shroud01-prt-15.zip

D

Dan_Harlan

AuthorAnswer

1-Visitor

Ok, making progress.

First thing I found (and my first mistake) was thinking that the wireframe curves would be sufficient for defining the curvature was wrong.

Second, I found that the surfaces (even if the part won't actually have those physical surfaces) adjacent to the smooth (G2) surfaces must be defined. In my case, these were the two cylindrical surfaces that represent the final smooth airflow direction and the 'rim' type surfaces perpendicular to the airflow.

With those surfaces, I could then go and define the end points of my styles curves to be Continous.

Then I could go and make connections between the style surfaces and my reference continuos surfaces by selecting the broken line indicators.

If more than one surface was possible, then you would get a prompt like this (asking if the red surface was the correct surface to connect to).

Once those connections were made, then I could set those connections to be surface continous (they defaulted to tangent).

Still have some investigation to do and cleanup, but this looks like a solid solution.

T

TomD.inPDX

17-Peridot

Be careful with mirrors. I am seeing some interpretation going on when you mirror with some assumptions. not every feature truly mirrors! I noticed this when I used curvature analysis but it was clear with the knot analysis...