General Mechanical

General Mechanical

node ordering stiffness and mass matrix

    • LisDeb
      Subscriber

      Hi all,


       


      I have a model (made up of solids with 3 degrees of freedom at each node) from which I extracted the stiffness (and mass) matrix unsing APDL Math commands:


      *DMAT,MatKD,D,IMPORT,FULL,file.full,STIFF


      *PRINT,MatKD,KDense.matrix


       


      This works, however when I tried multiplying the stiffness matrix with the displacements I got from a static solution (I got the displacements in all 3 directions from list results--> nodal solution) to make sure this corresponds to the external force vector, it occured to me that the node ordering cannot be consistent since almost every node has a nonzero value, while I only applied loads on two nodes.


      Does this have to do with the fact that *DMAT works with BCS ordering (https://www.sharcnet.ca/Software/Ansys/17.0/en-us/help/ans_apdl/apdldofordering.html) while the displacement exports that i got have a different nodal ordering? how can I transform the stiffness matrix in order to make it match the displacement results I exported?


      Thank you!!

    • Sandeep Medikonda
      Ansys Employee

      Hi,


      Can you check out example 4.2 in the ANSYS Parametric Design Language Guide*SMAT with NOD2BCS looks like what you need. 


      Please do not share any sharcnet links. Use ANSYS Help or the Help Packaged with your installation. I also recommend you to upgrade to 19.2.


      Guidelines to the Student Community
      How to access ANSYS Help


      Regards,
      Sandeep

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