Structural Dynamics

Structural Dynamics

Are .dmig/ .sub files generated from .full files?

    • FAQFAQ
      Participant

      The answer is No. The Nastran .dmig file is a text file that acts basically like our superelement binary file (.sub). It is used to represent the stiffness (and mass) of the structure without supplying the FEA details. In order to do this in a practical manner, though, the user needs to specify the master DOF and perform a substructure analysis. Basically, we don’t just dump the [K] matrix from the .full file as a .dmig file because the .full file contains the entire FEA mesh and thus has a lot of unnecessary information. Instead, what should be done is to identify the ‘attachment points’ (where this model will ‘connect’ to other parts in the other model), and the stiffness (and mass) matrix of the subassembly will be calculated in a substructure generation pass. This is in the .sub file, which can then be exported to a .dmig file.