Re: Rolled sheet

[Ralf Hielscher]

Maybe you can explain me a bit more what is the difference between orthorhombic and orthotropic specimen symmetry.

[Judy]

I, too, am interested in clarifying this point (apologies if it's been answered elsewhere, and bear with me as I reason this out to myself..)

Orthotropic means the properties of a material vary in 3 orthogonal directions. Wood is an orthotropic material because the properties vary. A rolled plate is also described as orthotropic (but not because the sample itself is typically rectangular. Instead, it is because the properties are different in the longitudinal, transverse, and normal directions.)

Orthorhombic is traditionally used to describe crystal structures only. The definition is "of, relating to, or constituting a system of crystallization characterized by three unequal axes at right angles to each other." So the key here is that the lengths vary in three directions.

So, wood is an orthotropic material. However, unless i cut it into a rectangular block it would have no characteristics being described as orthorhombic.
Similarly, if I cut my rolled plate into a cube specimen I am left with an orthotropic material without orthorhombic symmetry.

It's a very slight difference, and I'd be happy if someone can correct me! But I believe a rolled plate should have a specimen symmetry described as "orthotropic" and not orthorhombic.
That's all just semantics, though, if the code is accounting for the variation in material properties in 3 directions by inputting SS=orthorhombic

[Judy]

Last thought - a rolled plate would actually be
SS = "triclinic"
because the properties vary at all angles.

Is this correct?

On Friday, March 1, 2013 at 4:29:25 PM UTC-5, Ralf Hielscher wrote:

[Ralf Hielscher]

I just learned that orthorhombic is usually not used for sample symmetry. Orthotropic is indeed the right notation here and I should make MTEX aware of this, i.e., in MTEX 4.1.0 you can set

ss = specimenSymmetry('Orthotropic')

Note that MTEX always will assume the symmetry axis to be aligned with X, Y, Z. By the way what are the sample symmetric expressions for triclinic and monoclinic? Until MTEX 4.0 you should use 

ss = specimenSymmetry('Orthorhombic')

instead which will not make any difference at all.

Ralf.

On Thursday, February 14, 2013 at 12:05:33 AM UTC+1, nitin chandola wrote:

I have the odf's from VPSC analysis of a rolled sheet. The sample symmetry is "orthotropic" however mtex only allows "triclinic" , "orthorhombic" or "monoclinic" options none of which generate symmetric (about rolling direction) pole figures.  How can I include this inherent symmtery of an orthotropic sheet? 

 

Note: Mtex is an amazing software and has been extremely helpful in improving my limited knowledge on texture analysis. This is a personal thank you note to the main developer and all contributors. 

Cheers