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using Rayleigh Damping

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hi every one

i was modeling buddy floating. i was thinking to ad valye for i was modeling buddy (alfa and beta) any ideas how to calculte this factor ? or any hints to find out how its work



thanks alot

3 Replies Last Post 2010年11月8日 GMT-5 01:02
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2010年6月3日 GMT-4 12:47
Hi

Have you checked the pags 140++ of the smeug.pdf doc ? I believe that should give a reply, no ?

And do an indexed search of "Rayleigh Damping" on the docs, there are more in there, and in the other documents, even somewhere a matlab scripts to optimise the two variables

Have fun Comsoling
Ivar
Hi Have you checked the pags 140++ of the smeug.pdf doc ? I believe that should give a reply, no ? And do an indexed search of "Rayleigh Damping" on the docs, there are more in there, and in the other documents, even somewhere a matlab scripts to optimise the two variables Have fun Comsoling Ivar

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Posted: 1 decade ago 2010年11月7日 GMT-5 05:44
Hi Ivar,

I've checked the pages. I still think it's not that clear how to obtain the constants (alpha & beta). There is some information about damping in 'smeug.pdf' (pages 140-148, 199, 372). However, it seems that the procedure of the constant calculation is not clear. They address a reader to the Elbow Bracket example (smeug.pdf' pp 36-37). In this example, they assume that "the structure has a constant damping ratio of 0.1."...Actually, if we assume another number we will get different damping parameters.

I posted the question about this issue earlier (www.comsol.com/community/forums/general/thread/10886/)...

Please advise,
Stephan
Hi Ivar, I've checked the pages. I still think it's not that clear how to obtain the constants (alpha & beta). There is some information about damping in 'smeug.pdf' (pages 140-148, 199, 372). However, it seems that the procedure of the constant calculation is not clear. They address a reader to the Elbow Bracket example (smeug.pdf' pp 36-37). In this example, they assume that "the structure has a constant damping ratio of 0.1."...Actually, if we assume another number we will get different damping parameters. I posted the question about this issue earlier (http://www.comsol.com/community/forums/general/thread/10886/)... Please advise, Stephan

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2010年11月8日 GMT-5 01:02
Hi

the thing is that most damping in structures are not a material parameter issue but an assembly issue (welding, bolting, crimping "sqeezing" ...) and for these there are only the measured values that are valid, all the rest is only hypothesis

--
Good luck
Ivar
Hi the thing is that most damping in structures are not a material parameter issue but an assembly issue (welding, bolting, crimping "sqeezing" ...) and for these there are only the measured values that are valid, all the rest is only hypothesis -- Good luck Ivar

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