Orthotropic element orientation

[Stefan2653]

Is there a way to orient orthotropic brick elements (thermal) to the global coordinate system rather than to model nodes? If I make changes to the model and the node numbers change, I must re-assign all the orthotropic element orientations to the new node numbers, which can be a tedious process.

[S.LI]

The following is from product help.

Not sure if it's what you need.

If this part of brick elements is using an orthotropic or general piezoelectric material model, you will need to define the orientation of material axes 1, 2 and 3 in the Orthotropic or Aniostropic tab of the Element Definition dialog, respectively. There are two basic methods to accomplish this.

The first method is to select one of the global axes as material axis 1. If you select the Global X-direction option in the Material axis direction specified using drop-down box, the orthogonal material axes follow the X, Y and Z axes as follows:

• Material axis 1: X axis
• Material axis 2: Y axis
• Material axis 3: Z axis

If you select the Global Y-direction option in the Material axis direction specified using drop-down box, the orthogonal material axes follow the X, Y and Z axes as follows:

• Material axis 1: Y axis
• Material axis 2: Z axis
• Material axis 3: X axis

If you select the Global Z-direction option in the Material axis direction specified using drop-down box, the orthogonal material axes follow the X, Y and Z axes as follows:

• Material axis 1: Z axis
• Material axis 2: X axis
• Material axis 3: Y axis

The second method is to select the Spatial Points option in the Material axis direction specified using drop-down box. Next you must define the coordinates for three spatial points in the Spatial point coordinates table. Next, select the appropriate index for the spatial points in the Index of spatial point 1, Index of spatial point 2 and Index of spatial point 3 drop-down boxes. Material axis 1 will be a vector from the spatial point in the Index of spatial point 1 drop-down box to the spatial point in the Index of spatial point 2 drop-down box. Material axis 2 will be perpendicular to local axis 1 and will travel through the spatial point in the Index of spatial point 3 drop-down box. Material axis 3 will be calculated as the cross-product of material axis 1 and material axis 2.

ImportantThe spatial point coordinates are shared by all the parts in the model. Changing any of the coordinates in one part will affect all other parts that use the same spatial point.

[Stefan2653]

Thanks for the response. However, I am working in steady-state thermal with brick elements. I have selected orthotropic elements in the element definition dialog box. Under the orientation tab, the only options I see are to define orientation nodes 1, 2, and 3. There is no option to align to the model axes. Enclosed are snapshots of the dialog box.

[S.LI]

I see.

What I pasted here is for MES.

Not sure about thermal.

Sorry.

BTW:

To add thermal into your subject may be helpful for thermal experts to locate this post.

[Stefan2653]

Thanks, I will resubmit.

[hupn]

Hi,

Unfortunately, currently there are no other ways to specify the orientation for thermal orthotropic element, For the detail description, you can click the "help" button under the "orientation" tab. Then find the description regarding to orientation from the popped web browser.

hup

[Stefan2653]

Thanks. In my opinion, this would be something worth adding in future versions. Earlier versions of the software (Algor) did allow orientation by axis.

[hupn]

Hi,

Thanks for the info. Did you still remember which version of the old Algor supports this feature? It definitely raises the weight if this feature is available before :).

hup

[Stefan2653]

I'm not exactly sure which version, but last I recall seeing this option was probably about 4 years ago. We've been using Algor for about 20 years now...

[hupn]

That's fine. Thanks for the advise though.

hup

[AndreMarcic6025]

Hello,

I am facing the same problem with thermal simulations and I want to post an additional remark.

I usually took the node/vertices numbers after the meshing using the buttons "3D Mesh Settings-> Mesh Model"

As i got some awkward results, I checked the model and found out that the node in the results picture has a different number than after the meshing.

I changed the orientation nodes according to the results picture and re-run the analysis with seemingly better results.

Is my observation correct? What is the correct workflow?

regards

Andre

[John_Holtz]

Hi Andre,

Your observations are correct. At this time, the input for orienting the material axes are NODE numbers. The FEA Editor does not show nodes; it shows VERTICES. So after building a model, you need to use the "Analysis > Analysis > Check Model" command to get into the Results environment where you can select nodes and use "Results Inquire > Current Results" to get the node numbers.

Here's another idea for the next model. To orient the material axes with the global X, Y, Z directions, draw 3 lines on a new part number BEFORE you generate the mesh on the solid parts. These three lines would look like the mini-axis; one line points in X, one in Y, and one in Z. Define this new part to be rod elements. If I remember correctly, the node numbers (in the Results environment) are in the same order as the vertex numbers (in the FEA Editor). If the lines are drawn first, those vertex numbers will not change, and hence the node numbers should not change. You can remesh the CAD parts as many times as needed without needing to change the orientation nodes.

That's what I remember. Functions like this are handled automatically by the software and are "behind the scenes", so the routines may have chanced. But it is worth a try.