keeping curve length

[Mloew]

This sounds like a good application for BMX. Use an optimization feature that minimizes absolute value of an error function (abs(actual_length - desired_length)) by adjusting other control points.

 

[trillicomm]

One point has to be fixed permanently

Or

All three points must vary at the same time?

Are there any space constraints for these points in terms of 2D plane

 

[trillicomm]

The combination of pnt 0 and 2 for no-space-contraints is endless.

Because the pattern can be an arc (like an eclipse) or a sine wave.

One thing is certain that the segments going into point 1 (middle) is tangent.

thinking..

 

[trillicomm]

Question:

The blue curve, is it a guided rail for the point 0 and 2 to follow Along?

In other words, the slope of the two curves is unchanged or not?

 

[slashct]

You can use the perimeter function in sketcher to keep the length of the curves one but you need a dimension that you can vary. In this case you can create the curves than the distance between where the points are would be your varying dimension.
When I get to work I will open this up and modify it as an example.

 

[jeff4136]

I didn't bother to download your file 'cause I figured
I wouldn't be able to open it with WF2. Was I correct?


Will2008-02-10_142753_const_len_crv--wf2--.prt.ziphelp any
or are you trying to do a curve in 3D space?

 

[slashct]

You can use the perimeter function on your part since everything is on one plane and as long as you keep it that way. When you use this you need to tell ProE how to vary the curve as there can be more material, and if there is less it will fail, so you need to define this carefully on the situation.


To use it create a sketch and in your case I think you would want to use two conics through the 3 points. When done select the 2 conics, edit, convert to perimeter and than select a dimension you can vary. You will than see a perimeter dimension which is the length of the entire curve you selected. This you can set to a value and the other will change.


This is the idea,


2008-02-10_202447_curve.prt.zip


Depending on how you vary the point you might need to put a relation in to vary one of the other values, I am not sure what your trying to accomplish but this will work on what you show.

 

[slashct]

How are the ends allowed to move? is there a plane that is common to them and the distance is varied in only two directions?

If they are on one common plane, use a sketch to define the curve, I would do 2 straight sections coming out of the fittings, than use curves etc to define the transition, and than use the perimeter to drive the curve.

 

[andysuth]

I'm wondering if you can import datum points from excel and use either a goal seek through excel calcs alone (varying just one of the dimensions on a middle point) or a goal seek with an export of parameters from ProE.





-AS