hexagon logo
Register Sign in
  • State Not Answered
  • Replies 9 replies
  • Subscribers 4 subscribers
  • Views 83 views
  • Users 0 members are here
Options
Related

How does NODYNRSP do its thing?

anthony.carlson
Does anyone know how the NODYNRSP option of the RESVEC command do what it does?  
 
I haven't been able to find any documentation on this detail.
 
My (wild) guess is a low pass frequency dependent damping is applied to the modes associated with residual vectors to allow them to be suppressed at high frequency but allowed to responded at low frequencies... 
 
Second question on this topic (which is likely related to the first) is why the NODYNRSP option embedded into the RESVEC call. It seems like it could/should be a separate option on top of the RESVEC command.
Parents
  • 0
    Once the external SE is brought into the assembly run, the program no longer knows which modes are residual vector modes- they are all just 'modes'. Then, when these upstream modes are assembled and a new eigensolution obtained, the new modes could be a blend of those upstream modes and residual structure. There is no longer any means of removing just a portion of the 'new' modes dynamic response from the solution... only the residual 'assembled' modes can then have the newly calculated residual vectors appended. And these new residual vectors can be modified via the NODYNRSP tag to remove the modal mass so they don't respond dynamically.
     
    In your senario, you are just bringing down a single component into a residual with no additional structure... but that is not the normal case. Normally, you will be assembling upstream stuff with downstream stuff and doing a new eigensolution.
     
    But even in your senario, you will be resolving the 'system' modes since there are pysical and modal DOF coming down... you will perform a new eigensolution. At this point you can also generate residual vectors that can be affected by NODYNRSP.
     
    Sorry if this is confusing, as I am in a bit of a hurry!
Reply
  • 0
    Once the external SE is brought into the assembly run, the program no longer knows which modes are residual vector modes- they are all just 'modes'. Then, when these upstream modes are assembled and a new eigensolution obtained, the new modes could be a blend of those upstream modes and residual structure. There is no longer any means of removing just a portion of the 'new' modes dynamic response from the solution... only the residual 'assembled' modes can then have the newly calculated residual vectors appended. And these new residual vectors can be modified via the NODYNRSP tag to remove the modal mass so they don't respond dynamically.
     
    In your senario, you are just bringing down a single component into a residual with no additional structure... but that is not the normal case. Normally, you will be assembling upstream stuff with downstream stuff and doing a new eigensolution.
     
    But even in your senario, you will be resolving the 'system' modes since there are pysical and modal DOF coming down... you will perform a new eigensolution. At this point you can also generate residual vectors that can be affected by NODYNRSP.
     
    Sorry if this is confusing, as I am in a bit of a hurry!
Children
No Data
© 2025 Hexagon AB and/or its subsidiaries. Privacy Policy | Cloud Services Agreement