Problem Analyzing a Model with Orthotropic Materials

[Anonymous]

I'm working on a project for a class and have designed a trebuchet using SolidWorks.   I successfully imported it into Autodesk Simulation Mechanical and tested my Contact and Forces set-up using Isotropic materials (I used Iron Grey Cast 20)  and I got results.  However, after changing the Material definitions of the parts which are being modeled as wood and defining their Material Axis directions, I get the following errors when I try to run the analysis:

ds.l information and Details information

Spoiler

1**** CONTROL INFORMATION

number of node points (NUMNP) = 63876
number of element types (NELTYP) = 40
number of load cases (LL) = 1
number of frequencies (NF) = 0
analysis type code (NDYN) = 0
equations per block (KEQB) = 0
bandwidth minimization flag (MINBND) = -1
gravitational constant (GRAV) = 3.8640E+02
number of equations (NEQ) = 188124

**** PRINT OF NODAL DATA SUPPRESSED
**** PRINT OF EQUATION NUMBERS SUPPRESSED
**** Read 143 MPC's from CST file
**** Penalty based MPC method is used
ERROR - Error processing TYPE-8 elements
Error occurred with module: C:\Program Files\Autodesk\Simulation 2014\srunx.exe

Spoiler

**** Read 143 MPC's from CST file
**** Penalty based MPC method is used
**** Begin brick element (TYPE-8) data input
**** Part 1 containing 2703 elements

**** End input of element part 1

**** Begin brick element (TYPE-8) data input
**** Part 2 containing 2782 elements

**** End input of element part 2

**** Begin brick element (TYPE-8) data input
**** Part 3 containing 1176 elements
Two or more spatial points are coincident
ERROR - Error processing TYPE-8 elements

I'm not sure how to fix the problem.  Originally I thought it was being caused by my firing mechanism being too small and the meshes interferring at that location, however I have since completely removed that area and substituted a much simpler connection at that end which did not help with my errors.

I've attached a picture of my model and the results I got with Isotropic materials in case they help.

Thank you in advance for any help you can give me.

[AstroJohnPE · Accepted solution]

Hi SideshowH,

The "spatial orientation points" are the nodes or coordinates that are used to define the orthotropic material axes. My guess is that you did not define them, or at the very least, accidentally defined two of the three points to be the same. Go to the Element Definition for the orthotropic parts and define whatever the data is to define the orthotropic axes.

[Anonymous]

Thank you very much, that was indeed the problem. I found the instructions for how it calculates spatial points and was able to fix all of my parts so it successfully runs.

They were buried in the Plate Elements definition, which wasn't very intuitive as I couldn't find them in any of the Orthotropic topics. Just in case someone else runs into the same problem:

From the Plate Elements page
"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 1drop-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."