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A Mesh Generator and Pre-Processor for
FEA and CFD Analysis

Release Notes for TrueGrid®
Version 3.1.3, Dec. 14, 2015

1. Pressure (PR) and traction (TRACT) loads are now available for ABAQUS quadratic elements.

2. A bug was fixed in the merge phase when triangular faces were being selected for a face set.

3. A bug was fixed regarding the biased nodal zoning by the commands as and das (and sometimes res and drs). This bug only affected the cases where:

i. the edge was attached to a 3D curve

ii. the bias was severe i.e. large or small geometric ratio

iii. using quadratic elements (default is linear)

4. The macro control statements for/endfor, while/endwhile, and when/elsewhen/else/endwhen have been extended so that many more instances of these statements can be used together without running out of memory.

5. When lower numbered parts are displayed in the physical window while in the part phase with fill graphics, it was only possible to select nodes from the lower numbered parts that were along partitions of that part. Now, when selecting a node (to extract its coordinates), one can select any node that is visible.

6. The LLNL DYNA3D (DYNAMATS) material 24 had 4 new options:

i. Strength coefficient (SC) (for power-law hardening option)

ii. Hardening exponent (N) (for power-law hardening option)

iii. Initial reference strain (E0) (for power-law hardening option)

iv. Element deletion flag for plastic strain (EDF)
where 0.0 means no element removal upon failure
1.0 means element deleted when strain = effective plastic strain at failure

7. The as or das commands that distribute nodes along an edge with a geometric progression had a bug in it that sometimes caused TrueGrid to crash. This bug has been fixed.

8. The alltets command can be used in the merge phase, just before writing the output file with the write command. This command converts hex elements to tetrahedrons. Care is needed in using this command. It can only be used once when generating the mesh and only after all elements have been generated. It only works on hex elements. No wedge, tet, or shell elements are allowed. There is one more issue. If you build a mesh which is equivalent to a torus (ring) and it has a twist of 90 degrees or if there is an odd number of elements around the ring, then there be a disconnect someplace. This is because the hex element is being divided into 5 tet elements. There are other ways that a hex element can be divided into tets, but the quality of the mapping from hex to 5 tets was considered the best in quality. The purpose, primarily, is to allow for a fair comparison of the hex mesh to an eqivalent tet mesh. However, by making this feature available to users, we expect that some will use it to get a high quality tet mesh to run a simulation. So user beware, this feature may not be useful as a general tool for building tet meshes.

9. A minor bug displaying flux was fixed.

10. A minor bug was fixed when accuracy is increased and a composite surface formed frm trimmed surfaces. In rare cases, a single node may be lifted i off of the surfaces.

11. A bug was fixed with the high lighting of face and polygon selections whens they were degenerate. A bug related to this was also fixed regarding face and polygon sets.

12. When using the LS-DYNA output format, one can now generate up to 99,999,999 nodes.