Can anyone help me with converting stresses from cartesian co-ordinates to radial / cylindrical co-ords? I have in mind that it's not a simple vector rotation as stress is a tensor variable.
Any help / pointers appreciated!
Alison
Look up "Mohr's circle".
Olin Perry Norton
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(Sorry for the earlier goof, clicking to send before writing anything.)
I was trying to say it is not easy to explain through newsgroup postings. The basic mechanics of materials or mechanics of solids books may not give formulas on this. This is a 2-D elasticity problem. So you need to look up books on the latter for the formulas.
John
You might also find what you're looking for in a book on continuum mechanics.
Cheers - actually I'm working in 3D!
Alison
do you mean a conversion problem like this?
you have a stress at say 45 degrees to the z axis, and want to express it in terms of theta, r, and z instead of x, y, and z?
I believe you could use the cartesian to cylindrical coordinate conversions of x = r cos (theta), y = r sin (theta), and z = z.
If you are doing any integration, remember the Jacobian (r dr dz d(theta) )
and, if you need any expressions in terms of theta, using arclength = r*theta gives you an actual length (as radians are unitless).
does that do any good?
If you are talking about spherical coords, the conversions from x y z to r theta phi are way messier.
k w
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