June 5, 2023 at 5:52 amFady ElshazlySubscriber
Anyone knows how to definde spc in lsdyna during dynamic relaxation and to be released after that. I will prescribe in the transient step earthquake motion as boundaries using rigid part motion
June 5, 2023 at 1:04 pmRam GopisettiAnsys Employee
The spc constraints are honored in the DR phase when BOUNDARY_SPC with the BIRTH_DEATH option and DEATH eq 0.0 is used, but they disappear as soon as LS-DYNA enters the TRANSIENT phase.
June 5, 2023 at 9:02 pmFady ElshazlySubscriber
I am trying to do this but it seems not to be working properly. Is this because i am trying to use a set of nodes in a rigid body? is there another way to constrain the rigid body instead of spc set?
June 5, 2023 at 2:33 pmAndreas KoutrasAnsys Employee
To add to the previous response, on*BOUNDARY_SPC_NODE_BIRTH_DEATH you will need to set the DEATH equal to a tiny number, such as DEATH=1e-12.
June 5, 2023 at 9:04 pmFady ElshazlySubscriber
I am trying to do this but it gives error as it cannot be assigned to a rigid body nodes. Is this because i am trying to use a set of nodes in a rigid body? is there another way to constrain the rigid body instead of spc set?
June 5, 2023 at 9:12 pmAndreas KoutrasAnsys Employee
For rigid bodies, please impose the constraints by prescribing a zero displacement through *BOUNDARY_PRESCRIBED_MOTION_RIGID (with VAD=2) at each of the dof you need to fix. As in the previous case, use a small DEATH time to release the constraints at the beginning of the transient phase.
June 5, 2023 at 9:29 pmAndreas KoutrasAnsys Employee
A correction for my previous response. In *BOUNDARY_PRESCRIBED_MOTION_RIGID, please do not define a DEATH time. Instead, in the *DEFINE_CURVE referenced by the LCID of *BOUNDARY_PRESCRIBED_MOTION_RIGID, set SIDR=1. This should work.
June 5, 2023 at 9:46 pmFady ElshazlySubscriber
I will try it and let you know what is going on.
Thank you so much.
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