Set normal vectors on surface boundaries 3

[jones274]

Hello,
I'm struggling to solve this problem but I need some help because I don't know how to go on.
The problem regards the construction of a couple of surfaces, sharing one edge (in form of a spline curve).
Is it possible to impose the normal vectors of the two surfaces along their boundaries (in particular along the shared edge) on some arbitrary points near the edge?
Thanks in advance!

jones274

 

[JohnRBaker]

When you say "impose the normal vectors of the two surfaces . . . on some arbitrary points" what exactly do you mean and what is it that you're attempting to accomplish? Could you perhaps provide at least an image of what you're attempting to do?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
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[jones274]

Hello and thanks for your reply.
In particular, I want to take a set of arbitrary points along the edge shared between two surfaces and then, for each of these selected points, I wanto to set the surface normals for each surface, forcing them to respect those imposed boundary condition (the normal vectors).
I hope I made myself clear.

Here's an image

Thanks again

jones274

 

[JohnRBaker]

First off, what version of NX are you using?

Second, are you talking about making these 'vectors' parallel to each other, in other words, are trying to make these surface 'tangent' to each other? If so, have you looked at the 'Match Edge' function?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[jones274]

I use NX 10 for Windows and yes, I want exactly to set the tangency between the two surfaces, but only one some selected points along the shared edge. In some other points I'd like for instance to set a fixed angle between the two normals.

 

[jones274]

Is it possible to do this kind of "selective tangency" operation?

 

[JohnRBaker]

Not interactively with any existing NX function, at least none that I'm aware of. Perhaps a custom application could be written using NX Open that would accomplish that.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[jones274]

Thank you, this is exactly what I was afraid of

 

[jones274]

Hello again,
I tried to step back and watch my problem from a different angle, maybe by rethinking the basis of the problem itself.
Since my goal is to find a logic to reconstruct two surfaces, which may be tangent and/or not-tangent along their shared edge, first I have to understand how those kind of surfaces are modeled via the modeler/cad.

In particular, how are the surfaces containing this sort of "fading out" edge (crease) generally modeled in NX by a designer?
To better explain what I'm asking I think it will be useful to post a couple of examples.

Thanks again!

P.S.: I tried also to ask this in another section, since I'd like to understand the generic procedure (valid for various CAD environments) but they had suggested to ask the specific software sub-forums.

 

[Xwheelguy]

Here's a pretty simple version of transitional surfaces similar to what you've circled above (built in NX9). NX's Edge Blend has a nice option called 'Special Blend At Convex/Concave Y' that allows the blend to flatten out to an infinite value. You should be able to find it in the attached model.

The above examples are variations of my example, however, they are all going to be curvature continuous and would probably be a bit more difficult than my example to build due to both the shape of the larger surfaces and the higher level continuity (curvature continuous or G2) - however, the concept of transition is not much different.

Transition.prt

Tim Flater
NX Designer
NX 9.0.3.4 Win7 Pro x64 SP1
Intel Xeon 2.53 GHz 6GB RAM
NVIDIA Quadro 4000 2GB

 

[CNSZU]

jones274, if all you want to do is a transition and can accept G1 continuity, then Tim's suggestion is excellent. However, the examples you showed are A-class surfaces, which require G2 and G3 continuity. These surfaces require a lot of work. I suggest you go to the website of Autodesk's Alias software and read their excellent introduction and tutorials on A-class surfaces, and try to figure out how to do it in NX. Unfortunately, there is not much learning material on A-class specifically for NX, but most the principals on surface construction can be applied to most high end CAD software.

NX10.0 Win8.1 64bit i7-3770K 16GB QuadroK2200

 

[CNSZU]

John Baker, since Daimler switched to NX, do you know what software they use for the styling surfaces? NX, Catia ICEM Surf (seems like they were doing) or outsourced to freelancers?

NX10.0 Win8.1 64bit i7-3770K 16GB QuadroK2200

 

[JohnRBaker]

When I was at Daimler in Stuttgart last fall virtually all of my time was spent with people from the drive-train group so I have no direct knowledge of what the Body-in-White groups are using. I guess I could ask around and see what I can learn. The only issue is that this sort of information really shouldn't be shared on a public website.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[jones274]

Ok, this is much clearer now.
The thing I want to do is to understand the common workflow followed by the designers in these type of modeling (creased surfaces, preferrably made with A-class surfs). I've got an educational license for NX so I'm asking in this section: I honestly don't know if NX is the best tool for this kind of surfaces, maybe I've to ask some Alias users.
Meanwhile I whish to thank everybody for the help, this is much appreciated.

Have a merry christmas!

 

[CNSZU]

Jones, if you want to learn A-class surfacing techniques, Alias is the way to go, there is a huge amount of information available. However, in the realm of A-class or "technical surfacing" there is really no preset workflow to follow, it's mostly a black art and depends on each situation. The best way to learn about specific surfacing issues is search on Youtube, there are many videos from car body gurus who explain how they create certain surfaces using Alias. Then, having learnt the techniques, you can then port that knowledge to NX (where possible).

NX10.0 Win8.1 64bit i7-3770K 16GB QuadroK2200

 

[CNSZU]

John, I'm asking because I'm curious if the surfacing capabilities of NX can compete against ICEM Surf (or Alias) for commercial car body styling. If NX is not used for the styling, are there plans to increase the capability/functionality of NX so that it can be used for that purpose in the future? Has this factored in the decision of Daimler to switch to NX? Because if the styling can be done in NX, then that might lead to huge cost savings for Daimler since NX is all parametric and there is no need for translation of the surfaces.

NX10.0 Win8.1 64bit i7-3770K 16GB QuadroK2200

 

[Xwheelguy]

CNSZU,

I seriously doubt if Daimler will ditch their preferred styling/industrial design software in favor for NX. GM, FCA (Chrysler) and Nissan all use NX as their corporate CAD software, however all 3 still use Alias for their styling/ID needs.

In 20+ years I've yet to see an automotive company ditch Alias in favor of any of the 2 major softwares typically used as their corporate software. They still import from the ID software into NX. Can't speak for the CATIA side as I've only dealt with Honda and they also import Alias surfaces into CATIA, or at least they did less than 5 years ago.

NX can create Class A surfaces. The issue in doing so is similar to Alias - you've got to understand how to utilize the tools available to properly create the required curves and surfaces as well as how to analyze the results. That's for what the NX Shape Studio product is used.

Tim Flater
NX Designer
NX 9.0.3.4 Win7 Pro x64 SP1
Intel Xeon 2.53 GHz 6GB RAM
NVIDIA Quadro 4000 2GB

 

[CNSZU]

Thanks Tim, that's very interesting. Do you know why the styling departments prefer to stick with Alias? You'd expect the upper management folks to not be very happy at having a separate software for the styling, they usually prefer conformity. Is Alias that much better or is it simply a case of old habits die hard, stubbornness, and the notion that "we are creative, so we have to be different and use our "own" software" on the part of the stylists?

NX10.0 Win8.1 64bit i7-3770K 16GB QuadroK2200

 

[JohnRBaker]

There are many issues at play here. For one thing, even in a company like GM or Daimler, the number of Alias seats is relatively small compared to the mainline CAD system used throughout the rest of the company.

Another issue is that the 'Art' schools where most automotive designers are trained almost all use Alias in their curriculums. Granted, we've done a good job of getting NX and our CAE and CAM software into universities here in the US and around world, including many of them who have traditionally supplied engineers to the auto industry, however the designers attend very different and specialized schools.

Now outside of the automotive world, there are a lot of places where NX is being used for ID (Industrial Design), so the basic tools are there, it's just sometimes tradition is a hard act to overcome.

Now some asked whether NX can compete against products like ICEM and Alias, and while we think we can, we have to also choose our battles. While it may not appear that we've had a lot of success competing for the limited number of seats in the various auto studios, we feel that we can offer a viable solution for the small to medium sized companies, or even some larger ones, who are looking to add ID capability to their organizations who are already using NX for CAD/CAE/CAM but who have not used any dedicated styling software in the past like ICEM or Alias. Potentially there are a larger number of seats available to for us to win than what is currently in use by the automotive OEM's. This is the market that we've positioned products like NX Shape Studio with it's new 'Realize Shape' tool as well as the work that we did in rendering for NX 10.0 and what we're continuing to do in NX 11.0.

To learn more about what I've commented on above, please go to:

http://www.plm.automation.siemens.com/en_us/products/nx/for-design/industrial-design/index.shtml

And please check-out the list of 'Case Studies'.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[CNSZU]

Thank you John for the explanation!

NX10.0 Win8.1 64bit i7-3770K 16GB QuadroK2200