Deforming a texture - global shaping?

[hudson888]

We have a task to create a lens with thousands of tiny pyramids,(four sides 1mm square 0.2 high). These are arranged in a grid pattern approx 60 by 40 in a thin flat block with a 0.1mm gap between them at the base.

The desired result is as if a thin flat sheet with these pyramids all over it were to be bent curved in both directions to fit a slightly contoured surface. That is to say that the surface has differing curvature in U and V directions.

I have tried to use global shaping and I have got a result. The result is a solid bent accurately to fit the shape of the surface. Unfortunately the pyramids at the outer edges are skewed slightly towards the center in a way that simply wouldn't happen if the part were flexible and wrapped to the surface.

I've tried overcrown and stretch options with identical results. I can't see how a law function would work in this case, but I'm certainly willing to be corrected.

We're using NX-3. I can't spot any real difference in NX-4 and we haven't installed NX-5 yet.

If anyone knows of a better way to tackle the problem I'd appreciate your suggestion.

Regards

Hudson

P.S.

We know that we can get the desired result if we create sweeps in either direction alternately uniting and subtracting. However this is long winded tedious and the model quickly becomes quite heavy indeed.

 

[Xwheelguy]

Some images would really help if possible.

Tim Flater
Senior Designer
Enkei America, Inc.

http://www.enkei.com

Some people are like slinkies....they don't really have a purpose, but they still bring a smile to your face when you push them down the stairs.

 

[hudson888]

I don't know where I can post and image here? But I have a simpler way to explain it.

I have done some more testing and simplified the example so I can better describe it.

Simply put if you create a base 100x100x1 with a rectangular pad 20x20x10 high, and place it 4mm from either edge in one corner. Then you create a rectangular array 4x4 with 24 spacing either way, you will have 16 pads on on a flat square base.

If you apply global shaping to that body using either a surface or a function so the the center of the model is deformed upwards then the base and the tops of the rectangular pads are deformed, but the sides of the pads are not. The sides of the blocks remain aligned straight up and down. I want to be able to make it like the model was bent or wrapped to the deformation so that the sides of the blocks remain normal to the base.

I hope that explains it better

Hudson.

 

[MSPBenson]

How about a general pad with a face normal taper??

Mark Benson
Aerodynamic Model Designer

 

[hudson888]

Mark,

For the simple example the general pad actually works, as one may expect that it might. It is a good suggestion and one that I hadn't thought of. I used the results from my earlier foray using global shaping to extract curves on the surface. Just laying out 1000 odd squares at even distances on a curved surface would otherwise

However the original example was to create pyramids which come to a point. That is to say that if the 20x20x10 block on a flat base has a 45 degree taper then a pointed pyramid is the result. If you apply a 45 degree taper with the general pad creation there is a small flat left at the top. This makes sense because the curved surface imparts some variation to the taper. Since the surface is curved slightly different amounts in U and V directions there is a slightly rectangular flat spot on the top of each pad.

I had to check out your suggestion to see if it worked. Unfortunately general pads will only accept one boundary per pad. Had this worked I would not relish the task to create about 1000 general pads individually.

Happily we don't have to do this often, and in the process I learned about the limitations and benefits of using global shaping which is a good tool if you want to overcrown and preserve the basic shape. In this case it just happens I wanted to bend the model which is another thing altogether, perhaps a worthwhile enhancement in the future.

I seem to remember hearing about various tools for creating lettering on curved surfaces. If anyone knows about some of those there may be an opportunity to adapt some of those for this texture application.

Regards

Hudson.