Datum curves from file , how can i create it?? 1

[LiquidDesign]

Hi
I got a curiosity , i want to know how to create a curve from file, the file extension must be .ibl
Tanks in advance
bye

 

[cadcamguy]

LiquidDesign,

if you want to get a look at ibl format then ;

from insert datum curve.. bring in a small iges file instead

then select curve from model tree

edit definition <redefine> / curves / edit file

it will be in ibl format

 

[Olebole]

Hi,
I am new to this thread and have found it very informative. I am trying to loft a windturbine blade and want to import a bunch of loft-lines as datum curves from a spreadsheet. I have created a macro that writes the .ibl files, but I need to have a tangency condtion at the end of the curves (in the z direction) to smoothly blend into my root barrel. I tried creating a spline with tangency, saving as IGES and then re-opening and editing as IBL, but the tangency gets lost. Does anyone know how to code this into the IBL format?

 

[jeff4136]

> ... tangency ...
> Does anyone know how to code
> this into the IBL format?

No can do.

A curve is defined by Control Vertices and Knots. The IBL is the knot coordinates. The CV coordinates will be defined by the system. The curve end point tangent directions are defined by the position of the second CV on each end. There are ways to, directly or indirectly, manipulate the position of the CV but to do so may open a can of worms leaving you with an inferior or, ultimately, unacceptable approximation of the desired curve.

Creating a spline with tangency is not necessarily a good test. Depends on how the curve was defined. The IBL you created by IGES out, IGES in, Edit File extracts the curve knot coords which won't resemble your spreadsheet generated point distribution and density unless you created your test spline with that in mind.

I'd simply try (as you probably have by now) reading in spreadsheet generated curves and evaluating tangent directions using appropriate Analysis tools to start with. The IBL point distribution and density should be such that the curve tangent direction will be within your desired tolerance without additional manipulation. If it's not, trimming and blending surfaces may be preferable to manipulating curves.

There are alternatives that you might also investigate...

_ Create datum curves from equation vs. (and preferable to uniform point distribution) spreadsheet calculations.

_ Format the IBL for CSys Offset Datum Point read in. Create datum curve thru points (whole array). You can then define curve end constraints.

_ Manually fit bezier or b-spline curves (would be appropriate if you desired swept rather than blended / lofted surfaces).

_ Read or copy geometry into an Import / Independent Geometry / Style feature. There are a few different manipulation options that can be experimented with in that environment.

(Note: there are sample IBL files for curve and surface in Help. A Global Search for .ibl should turn up links or leads.)


-Jeff Howard (wf2)
Sure it's true. I saw it on the internet.

 

[gb420917]

I use ibl files all the time for turbine blade geometry, the geometry is broken in to section heights with each section split into four curves, there are generally 120 points per section, 10 for the leading edge and trailing edge radii and 50 points for the pressure and suction surfaces stopping at the tangency points. Specifing the tangency points is important and should be the start and end of each curve. The end of on e curve is the start of the next
The ibl file can be read in several ways not only to create a set of datum curves but a blended surface also. The blending into the barrel I presume this is the hub, surely this be done with pro/e and leave the ibl to carry the aerodynamic form only. I can upload an example section if this will help

 

[kimocal]

gb420917 please do. I have recently started to look at wind turbine blades and would like to see how it done.

Cheers,
KimoCal

 

[LiquidDesign]

Hi gb420917
If you can upload an example you will be so helpfull
Tanks a lot!!!
Bye

 

[Olebole]

Thanks for the suggestions!
At this point, I imported just the airfoils, and then used the style loft to control tangencies etc. My approach earlier was to also create loft-lines (strag lines) through the airfoils, but it seems Pro/E does a good job with a style loft so that loft lines are not necessary.