How can I further investigate the solution behavior of a steady-state dynamics analysis in Abaqus?

[direwolf11]

I investigate the dynamic behavior of a shell model in Abaqus (see appendix "03" for schematic system setup, all values in SI unities), which is connected to a spring-damper system.

Abstract of the model:
- Modal analysis + SSD solver (steady state dynamics)
- Material model: Composite material layup (see appendix "04")
- Mesh: S4R shell elements
- Connector Assignment realized by stiffness and damping connection (see appendix "02")
- Excitation via primary base motion (displacement)

Short Problem overview:
If a small stiffness is attributed to the interface (appendix 02), then the displacement of the nodes of the shell follows as in appendix 01.
As soon as the stiffness exceeds a certain value (appendix 06), the displacement of the nodes is 20x larger and
has no phase change at the resonance point. This seems physically unacceptable.


Does this point to a numerical problem that occurs at low stiffnesses in the connector?
How can the solution behavior of Abaqus be understood more precisely at this point?

 

[FEA way]

Which type of connector is used here ? Can you attach a picture of the whole model ? I assume that you can’t share the files. How are the natural frequencies in the first step affected by this change ? You could try using a different type of connection and simplifying the model (removing features from it one by one).