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Periodic Command

NairnFEA can do truly periodic simulations with optional extra degrees of freedom for periodic strains and rotations. The details on running periodic conditions on given on the OSUPDocs wiki. The command to set up periodic calculations in FEA us:

Periodic (dir),<(dof1),(value1)>,<(dof2),(value2)>

where

For periodicity to work, the edges of the specimen on the two ends of the periodic direction must be orthogonal to that direction, they must each have the same number of nodes, and the orthogonal coordinate (e.g., y coordinate for x periodicity, x coordinate for y periodicity, or r coordinate for z periodicity) of each node on one side must match the corresponding node on the other side.

Notes

  1. Adding periodicity will greatly increase the bandwidth of the problem. A Resequence Command can be used, but is unlikely to help.
  2. The Periodic command is only allowed for FEA analyses.