Autodesk Inventor

[#1]

Hello,

I would like to generate a rectangular pattern of extruded tubes which have an internal radius that is proportional to the distance to the centre point of the pattern.  Or in other words tubes which are narrower in the centre, and wider at the exterior.  Is there a way to do this without resorting to creating each tube individually?

More generally, is there a way to parameterise a feature dimension/parameter so that it is a function of spatial position?  

Many thanks,

Aaron

[#2]

Make the diameter dimension a function of the distance from origin of the pattern.

Can you attach an ipt here of what you have attempted so far?

Are you trying to do this a single part file or do you need as an assembly of parts?

[#3]

This would be a single part file, ultimately I want to make a single 3D solid which I can use in CFD, and also 3D print the structural volume.  I'm trying to homogenise flow in a manifold basically by adjusting the orifice diameter

I haven't attempted anything yet, so nothing to attach. However, a simple example would consist of a circular disc axially along z, 100mm diameter, 3mm thick.  A sketch would then be created on one face, and a 2mm circle drawn at the centre.  That would then be extruded (say 50mm), and then patterned isotropically in the x and y directions across the face, creating a 9x9 array of cylinders, with spacing 10mm.  I would like to be able to adjust the extruded cylinder diameter according to the radial position of each cylinder (so square root of x^2 + y^2) with respect to the origin.

[#4]

This sounds like a task begging for iLogic.

[#5]

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aoliver- wrote:

I haven't attempted anything yet,

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I think you should make the first attempt before anyone else.

[#6]

ok, here you go.  It's just a simple array of the cylinders though, I have no idea, barring manually creating each cylinder from its own sketched circle, how to change the radius of each cylinder based on its radial distance from the origin. 

[#7]

If it's just 9x9, it shouldn't be too much work to set it up with a geometric construction, using an angled line tangent to a row of circles to drive their diameters.  You only have to draw 1/4 of the circles, and then do a 4x circular pattern around the center.

Something like this:

It takes a while to set up, but with this method it should be easy to make quick changes to your parameters by adjusting the angle of the tangent line.

[#8]

That's pretty neat, thanks!

What about non-linear grading of sizes?  For example so that they change by a square law - can a curve be defined by an equation?

[#9 · Accepted solution]

IV 2013 has equation curves.  If you end up using an equation curve and require the diameters to exactly follow your non-linear scaling equation, just remember that the curve will have to pass through each circle at the same location. (eg. at the top point on each circle, rather than tangent to each circle.)

If you're using an older version of IV and don't need the non-linear scaling to be 100% accurate, you can approximate it with a spline.

CBliss has a couple of examples on his site for quadratic and sine curves.

Look at the bottom of this page:

http://cbliss.com/inventor/iFeatures/index.htm

If you're using an older version of IV and require 100% accuracy, you'll have to replace the tangent line with a set of parameters defined by functions, which could get a pretty tedious.