SwiftComp Periodic Boundaries

  1. Lina Shang

    Professor Yu,

          In part 3 of Gmsh4SCManual for creating user-defined model, the periodic boundaries are set for both 2D square pack microstructure and 3D Spherical Inclusions Microstructure, what are these periodic boundaries used for?

          I have built the same 2D and 3D SG model as Gmsh4SCManual by using Patran software (without the operation of setting periodic boundaries) and want to use these models and SwiftComp to calculate the elastic constants of some composite material, do I need to set the periodic boundary conditions in SwiftComp input file for this kind of analysis? If I use regular rectangles and cuboids for 2D and 3D SG respectively, the SCmanual says that nsalve can be set to zero, then how to mesh the corresponding periodic boundaries for 2D and 3D SG to make sure that the SwiftComp itself can search out the corresponding nodes on periodic boundaries?

  2. Xin Liu

    Hi Lina,

    I am a student in Prof. Yu's group, and I'd like to answer your question.

    Periodic boundaries are used to calculate effective properties of SGs, and this is a concept in micromechanics. In your case, you just need to make sure the corresponding boundaries have same mesh, then SwiftComp can find the periodic nodes on these boundaries automatically, and you don't need to set periodic boundary conditions in this case.  For example, if you want to use solid model to get 6 by 6 material stiffness matrix using 2D SG with regular rectangles, you need to make sure two vertical lines have the same mesh and two horizontal lines have the same mesh. If you want to use 3D SG to get material stiffness matrix, then you need to make sure the corresponding surfaces have the same mesh. 

    If the software you used cannot create the same mesh on the periodic boundaries, you can use Gmsh4SC and follow the instructions to create periodic boundary conditions.