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The frequency domain study vs. the frequency domain modal study
Posted 11.05.2012, 10:21 GMT-4 Acoustics & Vibrations, Structural Mechanics Version 4.2a 1 Reply
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I don’t know if this is a stupid question...but I have a hard time understanding the difference between the frequency domain study node and the frequency domain modal study node (in the solid mechanics interface).
Which study is the most appropriate one to use if I want to see the actual displacement and stress on a structure that is exposed to vibrations?
Which study is the most appropriate one to use if I want to see the actual displacement and stress on a structure that is exposed to vibrations?
1 Reply Last Post 11.05.2012, 10:46 GMT-4
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Posted:
1 decade ago
Hi
frequency domain is taking your FULL model and performs a solving based on the harmonic development of the equations (fixed sinus excitation at the "frequency" of your sweep range), and ALL right hand BC are used as excitation values
The Frequency Domain - Modal uses a eigenfrequency analysis to REDUCE your model to a few modes (you need to select these) and then you apply harmonic perturbations BC forces (you need to define amplitude and damping, although the latter seems not to work 100% yet in 4.2a, to be corrected for later version I have heard) on the REDUCED model.
For most models I use the Frequency Domain, but its very tempting to use the modal development for complex "havy"models, so long you manage to define which modes to pick AND that it working 100% as expected, as this should solve much quicker and give you still very usefull results
--
Good luck
Ivar
frequency domain is taking your FULL model and performs a solving based on the harmonic development of the equations (fixed sinus excitation at the "frequency" of your sweep range), and ALL right hand BC are used as excitation values
The Frequency Domain - Modal uses a eigenfrequency analysis to REDUCE your model to a few modes (you need to select these) and then you apply harmonic perturbations BC forces (you need to define amplitude and damping, although the latter seems not to work 100% yet in 4.2a, to be corrected for later version I have heard) on the REDUCED model.
For most models I use the Frequency Domain, but its very tempting to use the modal development for complex "havy"models, so long you manage to define which modes to pick AND that it working 100% as expected, as this should solve much quicker and give you still very usefull results
--
Good luck
Ivar