Write out local material orientation

Submitted by reneem5898 on Wed, 01/27/2016 - 02:56

I have set up a vibration problem. I assign a local material orientation by assigning coordinates a and b to define the 3rd material direction. From documentation, I understand that the other two directions are assigned to be orthotropic to the 3rd direction. Beyond that, I think that they are set somewhat arbitrarily. I want to output each component of the local material orientation.

*Orientation, name=Ori-DS_LV_DS_LV_FIBRES, definition=COORDINATES, system=RECTANGULAR

DS_LV_DS_LV_FIBRES

1, 0.

I found a way to output the local material orientation to the .dat file with:

*El Print, POSITION=AVERAGED AT NODES

This gives me the following in my .dat file. (Just the first few lines).

THE FOLLOWING TABLE IS PRINTED FOR ALL ELEMENTS WITH TYPE C3D8H AVERAGED AT THE NODES

NODE FOOT- E11 E22 E33 E12 E13 E23

NOTE

1 OR 1.0881E-03 -2.4529E-03 5.5659E-04 -3.6484E-04 -3.3336E-04 -1.3667E-03

1 SSD 3.4338E-04 7.5227E-04 -7.7260E-04 -6.8945E-05 -1.4456E-04 -1.4310E-03

2 OR -1.1083E-03 3.8331E-04 8.6723E-04 1.6965E-05 -5.9742E-04 4.4579E-04

2 SSD 7.3394E-04 -6.7419E-04 -4.6673E-04 6.4805E-04 -7.2251E-05 -1.6647E-03

3 OR -1.2586E-04 -7.8578E-04 9.5575E-04 2.8798E-03 2.1864E-03 -1.3924E-03

3 SSD -8.5076E-04 1.2290E-03 -1.8964E-04 -9.0878E-04 -7.5154E-04 -1.1113E-03

4 OR -9.3005E-04 -2.0169E-04 9.0388E-04 -1.6976E-03 -6.0696E-04 4.8134E-04

4 SSD 2.0887E-04 4.6213E-05 -2.5190E-04 2.5068E-04 2.9128E-04 -1.0801E-03

5 OR 5.3199E-04 -1.9483E-03 4.2709E-05 2.3164E-05 -7.6685E-04 -6.1928E-04

5 SSD 7.9289E-04 -6.5242E-04 -9.3984E-06 -6.1390E-04 -7.8684E-04 -1.2823E-03

6 OR -1.4705E-03 8.0179E-04 9.6646E-04 -2.2979E-04 8.8915E-04 1.9077E-03

6 SSD 7.2084E-04 -9.1113E-04 -3.0886E-04 2.4443E-04 -1.2574E-03 -2.0021E-03

7 OR 9.3148E-04 -2.4115E-03 2.1603E-04 2.3331E-03 2.0623E-04 -2.8699E-03

7 SSD 1.6355E-04 2.9455E-05 5.5929E-04 8.2595E-04 4.0638E-04 8.2047E-05

8 OR -5.3565E-04 -7.1252E-04 8.8212E-04 -1.5246E-04 -7.3226E-04 7.6021E-04

8 SSD -2.1401E-04 -1.2126E-05 6.5431E-05 -2.2339E-04 2.5891E-04 -4.2669E-04

9 OR 8.8023E-05 -1.9433E-03 2.3335E-04 -5.6005E-04 -1.6104E-03 -1.5217E-03

9 SSD 4.5202E-04 1.7247E-04 -1.0855E-04 -1.9394E-04 1.8261E-03 -6.4481E-04

10 OR -1.1895E-03 1.1078E-03 3.2344E-04 6.7851E-04 -6.4467E-04 -7.4874E-04

10 SSD -1.7305E-04 3.0125E-04 1.4873E-04 -1.2751E-04 -9.9659E-05 -3.6749E-04

Looking further into documentation, I understand that OR (orientation) is written out in "Type 85" format.

Record key: 85

Record type: Local coordinate directions

Attributes:	1 – First component of the first direction.
	2 – Second component of the first direction.
	3 – Third component of the first direction.
	4 – First component of the second direction.
	5 – Second component of the second direction.
	6 – Third component of the second direction.

I have two problems: 1) When I take the cross product of the these first two directions in the output orientation, I should get my 3rd direction. This, should be the same (or close to), my input fibre field interpolated at each node. However, the fibre directions are not equivalent (or even close) to my input fibre field. I also realise that there will be discrepencies because I am outputting the orientations averaged at nodes. 2) I would have expected the first two directions which were output to the .dat file to be orthogonal to one another, but they're not.

Is there another way to correctly output the local material orientation? Or if this is the true orientation, then I assume that the third direction may be far from my original fibre field due to the averaging of element orientations at the nodes. But then, why are the other two directions not orthogonal to one another?

Thank you for your help.

Also, I have attached both my input file.