Array of "Subdivide Face" in NX2

[innes]

I'm attempting to create a model of a plate, one of whose faces is subdivided into n equal pieces, where n is a user expression.

I've used a datum plane to define a line across the surface of the plate, then used "Subdivide Face" to do the first division. When I try to array the subdivision, NX2 tells me "SUBDIVIDE_FACE is invalid for this operation".

Any ideas?

 

[Xwheelguy]

I would just create a sketch or draw lines on a plane parallel to the face in which you wish to subdivide then using an Associative Curve Projection to project the curves onto the plate faces (project the curves perpendicular to the plane on which they reside). Finally I would subdivide the faces using the projected curves.

Alternatively, you could create the appropriate number of datum planes, associatively intersect the plate face with the planes, then use subdivide face.

Without knowing the shape of your part or the type of arrangement your array is in,(circular or rectangular) it's a little difficult to give you more suggestions. I personally need much more info about your part & its shape as well as the type of array to give you anything that may work besides the above suggestions.

Can you model ONE part of the plate THEN array it? For example, if the shape of my plate is cylindrical, I could model a pie section then create a circular array the pie. If the plate is rectangular, I can model one cube then use a rectangular array to create the whole plate....that's what I need to know up front.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

 

[cbrn]

Hi,
in addition to what Tim says, I think UG won't perform the array of "subdivide face" because the target surface's internal ID changes after each subdivision (the topology changes). I suppose there is no way to operate like that: as Tim says, the patterning of the "subdivider" has to be performed before the "subdivide" operation.

Regards

 

[innes]

Hi guys, thanks for your replies. Sorry I wasn't specific enough - sometimes things are very clear in your own mind but don't make much sense when you say them!

I have a square plate, 100x100x5 and am trying to divide one surface into an arbitrary number "n" of equally spaced strips, e.g. at x=100/n, 2*100/n, etc. It's important that the model updates automatically after changing the value of n, in other words no manual editing.

This is a very basic beginning, but the eventual goal is to establish a method to do automatic optimization using UG and our in-house FEA package. (Yes, I'm in over my head.)

I tried drawing lines in a sketch to define the subdivision lines, but couldn't find a way to make the number of lines change when n changes. I could sketch one line and pattern the sketch, but sketches aren't valid for patterning.

Datum planes have a similar problem - not valid for patterning. It isn't a big deal to create five parallel planes one at a time, but a making a hundred planes gets a bit tedious.

I've tried creating part of the plate, subdividing the face, then patterning the solid, but the subdivision is not copied to the instances of the pattern. I tried grouping the subdivide operation with the original solid and patterning the group, but that didn't work either. If that did work, the next step would be to Unite n solids into one, also hard to make update automatically.

I've found a way to make this work in some cases:
- offset by 100/n from one end face to create a sheet
- pick a number "m" to be the highest possible value of n
- array the sheets "m" times, 100/n apart
- intersect the sheets with a datum plane on the top face of the plate
- subdivide face using the lines

This updates correctly if you start with n equal to m and only ever change it to a smaller number. When n is less than m, the array of sheets extends past the opposite end of the plate. The intersection doesn't fail because the number of sheets doesn't change and they're being intersected with an infinite plane. Subdivide face doesn't seem to care if some of its division curves fall off the face.

I think this could probably be made to work the way I really want it to if there was a way to select entities by feature. e.g. if I could specify an intersection between the top face of the plate and every sheet created by LINEAR_PATTERN(21) rather than picking graphically.

 

[cowski]

Is this a planar surface you want to subdivide?

This is a very basic beginning, but the eventual goal is to establish a method to do automatic optimization using UG and our in-house FEA package.

It sounds like you want to subdivide the face, run FEA, subdivide the face more, run another FEA, etc etc. I have only a fairly basic understanding of FEA, but if you start with the same constraints and forces, shouldn't FEA report the same results whether the solid's surface is 1 face or 100? Or does the subdivide operation somehow control the meshing process?

 

[innes]

That's almost it, but the idea is to use the subdivision to control the constraints rather than the mesh.

For example, say the surface is subdivided into ten faces, with the even numbered faces restrained and the odd numbered faces unrestrained. Then we could vary the number of faces and see what it does to the natural frequency of the plate.

 

[hbarea]

Why NX2 and not NX3? In NX3 you could use the new pattern face.

Hector Barea
Tupperware

 

[innes]

That sounds interesting, but I am stuck with NX2. (And happy to have it - we used CADDS5 until a year ago.)

 

[Xwheelguy]

You can use pattern face in NX2, but it more than likely will fail, as I have yet to have any success trying to pattern a pie section of a wheel around.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

 

[hbarea]

I did not realize pattern face was available in NX2. I think I created your part. I can email it to you.

The first feature is a block of dimensions x=100+n*2, y=100+n, z=5.

Second, a sketch on the top face of the block of a rectangle, 3 sides are at a distance equal to n from the edges, the width of the rectangle is equal to n.

Third, subdivide the face with the rectangle.

Fourth, pattern the face, number along x= 1, along y=100/n, x offset = 0 y = offset equal n*2.

Last 3 features offset 3 faces by –n, done. Change n.

Hector