Help with solvers (Nastran)

[johnwang]

example under inp folder

https://github.com/nasa/NASTRAN-95/blob ... 06011a.inp

ctrmem2.jpg (17.07 KiB) Viewed 1257 times

ctrmem.jpg (54.84 KiB) Viewed 1257 times

[johnwang]

the TH = 90.0 is defined as

ctrmem4.jpg (12.97 KiB) Viewed 1254 times

Photo below is without drawing the 90 degree triangle

no90.jpg (65.06 KiB) Viewed 1254 times

[johnwang]

the 90 degree only elements

with90.jpg (25.23 KiB) Viewed 1214 times

[bernd]

How about the holes? Are these holes or elements with normals in the other direction? If the later you should set BackfaceCulling to False in the mesh View properties to show all Faces colored.

[johnwang]

How about the holes? Are these holes or elements with normals in the other direction? If the later you should set BackfaceCulling to False in the mesh View properties to show all Faces colored.

It is the normals. BackfaceCulling works. Thanks.

I tried to calculate the normal. If it is in opposite direction, then draw the triangle in the other node sequence.

cr2.jpg (78.57 KiB) Viewed 1143 times

[bernd]

Better to flip normals. For such a mesh all normals should go into the same direction.

[johnwang]

Better to flip normals. For such a mesh all normals should go into the same direction.

This mesh may be generated by hand at the old time, so they didn't pay too much attention to the normal.

Does it affect fea?

[bernd]

Better to flip normals. For such a mesh all normals should go into the same direction.

This mesh may be generated by hand at the old time, so they didn't pay too much attention to the normal.

Does it affect fea?

It should not. I have not had any so far. But you never know ... May be other had. I do not know. Thus it is best to not have them.

BTW: I have even seen commercial quite expensive FEA packages still create meshes with flipped normls.

[bernd]

you could try this:

- create a mesh object from it
- analyse and repair the mesh object (including normal directions)
- create a Part from it
- remesh with gmsh, use big minimal element size

[paul18]

Does it affect fea?

yes it does: among other things Pressure or Excentricity are defined thanks to the element normal