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Valued Contributor
oyvinkle
Posts: 56
Registered: ‎01-11-2013

Mass eccentricetis

106 Views, 5 Replies
02-27-2013 06:49 AM

I have run a modal analysis with the consistent mass matrix using the mass matrix offest with 5% and add modal masses with 5% and an anallysis with noe eccssentriseties. how come the offset mass matrix results are so different??

 

 

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Valued Contributor
oyvinkle
Posts: 56
Registered: ‎01-11-2013

Re: Mass eccentricetis

02-27-2013 06:51 AM in reply to: oyvinkle

wrote wrong on the pic. the nodal and matrix ar mixed up!

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Rafal.Gaweda
Posts: 4,935
Registered: ‎04-26-2010

Re: Mass eccentricetis

02-27-2013 06:54 AM in reply to: oyvinkle

Recomended to use Nodal eccenticities.



Rafal Gaweda
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Rafal.Gaweda
Posts: 4,935
Registered: ‎04-26-2010

Re: Mass eccentricetis

02-27-2013 06:57 AM in reply to: Rafal.Gaweda

Small explanation:

 

Adding to nodes -that's clear, masses are added \ moved from nodes to other nodes


Offseting mass matrix - whole mass matrix is shifted; by "kind of" rigid links it is linked with previous state and additionally small "rotation" of this matrix (masses) may appear because of "rigid links" so it is less phisical approach than shifting by adding masses to nodes.



Rafal Gaweda
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Valued Contributor
oyvinkle
Posts: 56
Registered: ‎01-11-2013

Re: Mass eccentricetis

02-27-2013 06:58 AM in reply to: Rafal.Gaweda

How come?

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Rafal.Gaweda
Posts: 4,935
Registered: ‎04-26-2010

Re: Mass eccentricetis

02-27-2013 07:02 AM in reply to: oyvinkle

???????????



Rafal Gaweda
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