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26 Dec 2024 08:21:09 EST (-0500)
  Modeling torsional stress - shear - strain (Message 1 to 2 of 2)  
From: Bald Eagle
Subject: Modeling torsional stress - shear - strain
Date: 8 Aug 2013 12:45:00
Message: <web.5203ca651764e2af45338b700@news.povray.org>
I'd like to model the shearing strain in an upright simple cylinder / tube.
While I'm working on the physics equations, with text outputs, I'm thinking
ahead (because designing models is much like playing chess against the render
engine) and want to graphically show the strain levels as colors.

Other than somehow using a pigment or normal map, I'm struggling with how to
model a static color field that the object "moves" through, yet shows the
initial state as a solid color.

Preliminary idea include:

Use a ripple pigment map and then make the cylinder a lathe or SOR, with the
diameter proportional to the strain, then try to make it look round again.
Can I do this in reverse and "pinch" a cylindrical pigment map inwards?

Stack a pile of short concentric tubes to resemble the whole tube, and declare
the pigment as a variable, such that the rotation angle and distance from the
center at that point changes the color?

Draw a grid or wireframe around the cylinder's surface, and model the twist by
using fhelix1 after the twist angle > 0, and having the helix intersect a radial
pigment map.


Thanks!


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From: Anthony D  Baye
Subject: Re: Modeling torsional stress - shear - strain
Date: 9 Aug 2013 14:20:00
Message: <web.5205321db9ca4379328783aa0@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> I'd like to model the shearing strain in an upright simple cylinder / tube.
> While I'm working on the physics equations, with text outputs, I'm thinking
> ahead (because designing models is much like playing chess against the render
> engine) and want to graphically show the strain levels as colors.
>
> Other than somehow using a pigment or normal map, I'm struggling with how to
> model a static color field that the object "moves" through, yet shows the
> initial state as a solid color.
>
> Preliminary idea include:
>
> Use a ripple pigment map and then make the cylinder a lathe or SOR, with the
> diameter proportional to the strain, then try to make it look round again.
> Can I do this in reverse and "pinch" a cylindrical pigment map inwards?
>
> Stack a pile of short concentric tubes to resemble the whole tube, and declare
> the pigment as a variable, such that the rotation angle and distance from the
> center at that point changes the color?
>
> Draw a grid or wireframe around the cylinder's surface, and model the twist by
> using fhelix1 after the twist angle > 0, and having the helix intersect a radial
> pigment map.
>
>
> Thanks!

Model the cylinder as a mesh and adjust the color of each triangle based on the
offset of it's vertices from where they should be.

you might be able to use a mesh camera to "bake" the texture (not sure how to do
this, but what I've read suggests it's possible.) and apply it to the cylinder
primitive.

regards,
A.D.B.


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