General Mechanical

General Mechanical

node ordering stiffness and mass matrix

    • LisDeb

      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:




      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 ( 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


      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.

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