Bad solution using S3 shell element and *DLOAD

Analysis issues
1

Hi everyone,

I’m using an S3 shell element to model a straight pipe under internally distributed pressure using *DLOAD (see link below). However, each run produces different and incorrect results (displacements, stresses, and strains) for the same pressure load value.

What is wrong? any suggestions?

This is the link to *.inp file:

Thanks in advance

Jack

2

Some remarks:

  1. I had to replace *CLOAD with *DLOAD in your file.
  2. It’s better to avoid S3 elements, you should use quads or S6 instead.
  3. For shells, you should set OUTPUT=3D in most cases to get bending stresses.
  4. You can try with PASTIX_MIXED_PRECISION output variable set to 0 in such cases: Distortion with S6 elements when using ccx > 2.17 and solvers other than Pardiso · Issue #104 · Dhondtguido/CalculiX · GitHub
  5. It might be better to use plane strain assumption or at least symmetry to model such a long pipe.
1 Like