Question about modeling practices in GSD

[VN1981]

I wanted to get some tips on good modeling practices in Catia V5 (or 3DExperience as well)...

Let me ask my question through an issue I am facing. Firstly, I am using mainly Generative Shape Design and some part design workbenches to accomplish my model. Trying to model some custom gills like openings on fuselage. I need to place same gills on bottom of the fuselage in one config & on top of the fuselage in another config.

Here is an overview of my workflow:
1. Create an offset plane at the bottom of the fuselage and use that as Sketch support plane.
1a.Design the profile in Sketch
2. Project the profile on to the skin
3. Use Multiple Extracts to get specific sides of the closed profile
4. On the multiple extracts, perform other operations like split, extrude etc.
5. Perform more operations to get my final design.

I was hoping for the 2nd config i.e. on the top, all I would do was change the position of the sketch support plane and everything would update automatically. Of course, Catia did not share my sentiments. I had to do some rework, especially with multiple extracts and so on...I know Catia somehow renames the edges & other objects internally and one has to re-select (Brep object moved or not found error) again but just wondering if there is a way to accomplish the above in Catia? i.e. just change the sketch position & things would update automatically with little rework!

Also, which operations in GSD are better stability wise? i.e. Catia won't ask to re-select over & over again for certain changes? Would appreciate some help.

 

[LWolf]

the key is to avoid using sub-elements... i.e. do not click on the 3D geometrie's edges, vertices or faces... Try to use the tree to select your input data. Which means you have to "design" your inputs in a stable/secured way...
This takes a few more steps, but pays off in terms of stability and updates... An example: rather than selecting edge from a surface, create a boundary feature. But you need to be consistent, i.e the boundary cannot be referring to vertices--sooo you need to find a stable way of creating those points that will serve as boundary limits. If the geometry does not change (too much...) between revisions then perhaps an extremum point feature will suffice...
An extract is almost always a sub-element based feature (except when you extract the skin of a solid, and you select the solid from the tree).

regards,
LWolf

 

[VN1981]

Hi LWolf,
Thanks for your reply. Let me repeat my question with an example

Lets say that I have sketched the above rectangle and have projected it on to a support. And I want to select/extract the two sides (pointed by arrows). How do I go about it? Because Project does not contain any sub-entities (at least not displayed in the tree).

 

[IanStupid]

There are several ways to avoid this B-rep problem and have reliable updates.
One is to create 4 GSD lines and project them separately. Keeping 4 distinct objects that will never get lost.
Or, in your sketch you could create 4 output features of the 4 sketch lines you created. These can be projected separately too.
Or there are clever ways using KWA knowledgeware commands to stabilise b-reps if you have the License, the knowledge, and the time.

 

[VN1981]

^^Thanks for your reply. It was definitely helpful. Need to explore option #3... We have a couple of full Catia license and so that is certainly not an issue...knowledge & time...now those are different aspects. Are there any good & easy tutorials you'd recommend to get started on KWA Knowledgeware?