Multi-section surface, area control

[hoover33]

I'm learning CATIA V5 after years using Pro/E. As a test for myself, I'm trying to re-create one of my toughest Pro/E designs in CATIA.

In Pro/E there is a feature called "swept blend" which is a blend (with as many intermediate sections as you need) swept along a center curve. The analog of this in CATIA seems to be the "Multi-sections Surface". There is only one problem. The surface I am creating is a duct and needs a specific relationship between cross-sectional area and position along the length of the duct. In Pro/E the swept blend feature can have an "area graph" associated with it which accomplishes this nicely. In CATIA I can find no such option.

Everybody says CATIA is better than Pro for surfacing... somebody please prove it and help me out here! ;-)

 

[jackk]

In CATIA V4 there was a surface option that used AREA as a parameter to sweep surfaces. Worked great for ducts, especially irregular shaped ones.

Unfortunately, I don't believe this capability is available in CATIA V5.

You'll have to figure out some other way to do it. Maybe build each cross section to have the required area?

Looks like Pro-E wins this one.

 

[hoover33]

I feared this.

Creating sections along the way would be very difficult. The shape is complex and it would be hard to define each cross-sectional profile (not to mention keeping the segment # the same as the end sections).

Any possible way to do it using "laws" or "formulas"? I haven't quite figured out either of these tools but am not sure if they're applicable to my dilemma.

Thanks.

 

[jackk]

I was thinking of using fomulas to "automate" the creation of the internal sections.

 

[nev99]

Hoover,

I think I have a solution for you.
But I don't see an option to upload a file.
I can mail solution to you if you give me an address.

Regards

Neville

 

[hoover33]

Neville,

Address is matt.b.hoover AT lmco DOT com.

I can't upload anything here because of sensitive nature of model.

Thanks!

 

[jackk]

Nev, how about at least sharing a description of your solution with the rest of us?

otherwise, please send me an email also: jack.knapp@bdk.com

 

[hoover33]

I agree Nev, post ideas here too please, if possible. Jackk, I haven't received any emails yet but I'll post my findings here, no matter what happens.

 

[nev99]

Jackk,

I wanted to post a possible solution but did not know how to upload the file. If there is a way to upload files please enlighten me.

Regards

Nev

 

[cadddict]

Nev99
check out this link

javascriptpenindex(450,450,'

http://www.tipmaster.com/includes/refinfo.cfm?w=450&h=450')

 

[jackk]

Nev, I'd just like to know how you solved the problem. You don't have to upload your solution if you don't want to.

 

[nev99]

Jakk,

Assuming the solution is valid

I built a guide curve.
Then added a parameter to extract its length(L).

I then built a direction line for the law of length L
I then added the area graph as a sketched spline starting at zero ending at L.

Then I added the direction and spline to the law

I did a sweep along a guide curve (circle option)
For the circle radius I selected the law option.

Regards

Nev

 

[hoover33]

Nev's solution sort of solves my problem, but not exactly in the way I was looking for. I wanted to use multi-section surface, which allows for intermediate sections (my section is much more complex than a circle). But MSS does not have a "use law" option. So somebody suggested I created every cross section where I want the areas controlled, but this would be impractical. I want a FEW intermediate sections, but not a bunch. Maybe I can get by with only end sections (sweep) if I use guide curves to help constrain the intermediate portions.

It is a shame laws cannot be applied to MSS, only to sweeps. Strange.

 

[PeterGuy]

are all the sections similar? i.e. do they have the same number of segments but varying in size & prehaps orientation. If so have a look at the adaptive sweep command.

 

[hoover33]

Peter, the two end sections are similar, one is a circle and the other is a sort of rounded trapezoid. They have the same number of sections. I like having the option to specify 1 or 2 sections in the middle (MSS) but not of being forced to specify all middle sections, it would be impossible to make it smooth.

I also lack "guide curves" that seem to be needed for sweeps... all I want to constrain it with is a "centerline" (spline).

I'll look into adaptive sweep and see what I can figure out, thanks.