Using an ODF

[atsushi-labo]

Hello,

Thank you to the developers of Neper for your great work.

I have a question regarding the tutorial "Using an ODF."
I understand that the number of elements in fr.msh must match the number of lines in odf.txt.

At the end of the fr.msh file, the Rodrigues vector is defined like this:

$ElsetOrientations
1 rodrigues:active
1 0.919953402851 1.412193625247 -0.358468593221
$EndElsetOrientations

The odf.txt file looks like this:

0.000000759253
9.942171443106
0.426465599961
…
(the number of lines equals the number of elements)

I have two questions:

Question 1

A Rodrigues vector is defined as:

r = n * tan(Θ / 2)

n = (n1, n2, n3): unit vector representing the rotation axis

Θ: rotation angle (in radians)

r = (r1, r2, r3): Rodrigues vector

Based on this definition, does the Rodrigues vector in fr.msh represent n, and do the values in odf.txt represent Θ?

Question 2

Would it be okay to arbitrarily change the Rodrigues vector part in fr.msh like this:

$ElsetOrientations
1 rodrigues:active
1 1.0 0.0 0.0
$EndElsetOrientations

and then set arbitrary values in odf.txt as well?

[atsushi-labo]

Sorry, correction:
1 and 2 are incorrect.

Neper -T -n 1 -domain "Rodrigues(cubic)" -o fr
Neper -M fr.tess -cl 0.05 -statelt x,y,z

I confirmed that the fr.stelt file is a Rodrigues vector. I also made sure that I entered the same number of intensities in odf.txt.
As per your answer to #943. Verification took me a very long time.

I will explain how I did it.

First, I calculated the ODF function from the measured data in MATLAB MTEX from the OIM Analysis. Then, I used that function to evaluate the ODF intensity at the position of each Rodriguez vector in the fr.stelt file and wrote it in odf.txt.

Is this procedure correct?
The odf.txt in the tutorial simulates a rolling texture, but I am very curious as to how it was generated.

Please let me know if this is possible.

[rquey]

Your procedure is correct.

The rolling texture comes from a simple Taylor crystal-plasticity simulation.