example CRM modal issue?

[jaredmagnusson]

Hello,

I'm running your examples/crm/crm_frequency.py script to generate the first 10 modes of the simplified uCRM-9 model (CRM_box_2nd.bdf).

At higher modes, specifically modes 7 and 9, I get strange displacements near the root of the wingbox.

Here is the root of the wingbox for mode 7 (deformations scaled by 50x in Paraview):

Have you seen this type of behavior before? I didn't see similar modeshapes with 2019 results at Mendeley Data: uCRM: undeflected Common Research Model. I'm planning to swap the Nastran mesh from Mendeley in this script to get a one-to-one comparison.

Further Information:

OS: RHEL 9
TACS commit hash: d97564d32093872d87d68facb26a3e2a4c932c4b

Build Dependencies:

• gcc/12.5.0
• mpich/4.3.1
• metis/5.1.0
• netlib-lapack/3.12.1
• python/3.11.13
  • mpi4py/4.1.0
  • numpy/1.26.4
  • pyNastran/1.4.1

[timryanb]

Hi @jaredmagnusson,

It looks like the mode you are showing might be a rib mode. My guess is the weirdness is coming from the exaggeration of the mode shape. The hump you are seeing come out of the root rib is probably coming from the exaggerated deformation of another rib further outboard.