[MBDyn-users] Static Analysis

David Cross (Civ, ARL/VTD) david.m.cross2 at us.army.mil
Fri Jul 9 15:43:25 CEST 2010


Thank you.  That should help me.

Another question...Im modeling flapping wing dynamics, and I am exciting 
motion at the natural frequency whose mode shape corresponds most 
closely to a flapping motion.  I was wondering if there is a way to 
prescribe proportional damping...say 1% of the structural stiffness??

Thanks again for all of your helpful advice.  Regards,

David



masarati at aero.polimi.it wrote:
>> David,
>>
>> please always reply on the list.
>>
>> The issue is strange, during static analysis the derivatives phase
>> should be' skipped (as far as I know).
>>     
>
> Derivatives are always performed.  However, it is correct that for static
> analysis they may pose some issues.  What you can do is either:
>
> - make sure the model is initially unloaded (at T = initial time), and
> load grows regularly to its final value; or
>
> - increase "derivatives tolerance" above the error that's computed during
> this phase.
>
> The latter approach is not that clean, resulting in some "fake" transient
> taking place from the first step on (since the model is static, so the
> transient would be purely numerical).  However, a well-behaving model
> should recover in just a few steps.
>
> Cheers, p.
>
>
> _______________________________________________
> MBDyn-users mailing list
> MBDyn-users at mbdyn.org
> https://mail.mbdyn.org/cgi-bin/mailman/listinfo/mbdyn-users
>   

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 10120 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://mail.mbdyn.org/pipermail/mbdyn-users/attachments/20100709/161ce1bd/attachment.bin>


More information about the MBDyn-users mailing list