However, my favorite use for frequency analysis has nothing to do with vibration at all. It’s the fact that a frequency analysis is more than happy to run with rigid body modes aka a non-constrained part. As you build more complex models, the need to use degree of freedom saving shells becomes more apparent to reduce the need for RAM and to decrease run times. When using shells, the application of contacts and connections is a little more involved than simply added global bonded contact to the model.
If you try to run a linear static analysis with a part that is not fully constrained, you will either get an error or a request to go into large displacement mode. At that point you can wait a long time to find out you missed a contact or connection. The other option is you can start your model in a frequency study and then drag and drop your constraints and connections over to a static analysis once you have run the frequency analysis and are happy with how the structure is behaving.
- Create Frequency study, No fixtures needed you can run “free free”
- Ask for at least 12 modes in study properties (first six will be close to zero and seventh should have stiffness aka be greater than 0 if all your parts are connected)
- Set up bonded contacts and connections in frequency study, run and check how part behaves
- Drag bonded connections over to the static analysis