OA Formulation-Flexible Body Input File

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hi everybody!

 

I am writing a FEM Code in Technische Üniversitat München and I have to deal with rigid body motion of my model somehow I need to eliminate RBM from total deformation to calculate internal forces in my structure and during searching on this topic, I found RADIOSS_10.0_Reference_Guide2.pdf on the net. Under the title of 'Flexible Body Input File' , it is telling that how to get RBM for the each node in the structure but for that we need four points like L1,L2,L3,L4 which  can create an orthonormal local frame and do not coincide with the mesh of the structure.

 

Guide tells that these four points are chosen arbitrarily and the distance between them does not change during the analysis ,so it means they are rigid. However, I wonder that how they can find the new positions of these points in the next time steps. They are saying that they have UL1, ... , UL4   which are the rigid body displacements of these nodes but my questions is how they are getting these values

 

P.s. : I also uploaded the guide that I found and the title is in  page 1124. 

 

Thanks in Advance

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Answers

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited July 2015

    Hi,

     

    Please find some more information from Radioss latest version 13.0 reference guide on Felx body input file. 

    See attached thumbnail.

     

    Regards

    Rahul R

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  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited July 2015

    Hi Rahul, 

     

    Maybe I am missing some points but  this latest version manual is almost same with the one I attached and I checked again but still I could not get how it is updating the points defining local coordinate frame in each time step.