October 9, 2018 at 7:53 pm

peteroznewman

Subscriber

1. If you want to sweep from 80 Hz to 200 Hz in 20 seconds, that is 6 Hz/second. You can break that up into four pieces of 5 seconds each.

- 80 - 110 Hz
- 110 - 140 Hz
- 140 - 170 Hz
- 170 - 200 Hz

That will make each analysis more manageable, but if something interesting happens at one of the breakpoints, you might miss it. You could overlap the ranges slightly to avoid that. That will give the same result as a single 20 second sweep of 80 - 200 Hz without bogging down the computer excessively.

2. The full model has 290 nodes which creates1068 equations. Using modal superposition involves taking six modes that might be described by 10 coefficients for the shape functions, or 60 equations. It is a lot faster to do time integration on 60 equations instead of 1068 equations.