Creating Periodicity Conditions

This task shows you how to simulate periodicity conditions by linking together the degrees of freedom of two faces that undergo transformation. You will apply cyclic symmetry.

Only available with the ELFINI Structural Analysis (EST) product.

Periodicity conditions enable you to perform an analysis on the solid section of a periodic part. This solid section should represent a cyclic period of the entire part as shown in two examples below.

Applying periodicity conditions is cost saving: you compute only a section of the part and get a result that is representative of the whole part.

Two types of periodicity conditions can be applied:

  1. Cyclic symmetry of the geometry as well as both restraints and loads.
    The actual part results from n rotations applied to the modeled solid section where n=2 II : teta should be an integer. 
  2. Regular symmetry of the sectioned geometry as well as both restraints and loads:
    The section is geometrically regular, there is no discontinuity. The entire actual part results from an infinite number of translations (right and left) of the modeled section.
           

To know more about this element, see Periodic Condition and Join Fasten in the Finite Element Reference Guide.

To use periodicity conditions, you need to make sure the geometry as well as the created restraints and loads are periodic. The geometry also needs to be regular at the place the section is cut: discontinuity is not allowed.

Open the sample44.CATAnalysis document from the samples directory.

  1. Click Periodicity Condition in the Virtual Parts toolbar.

    The Periodicity Condition dialog box appears.

  2. Select on the model both planes to be used for generating periodicity of the part section. In this particular case, select both pink faces.

    The selected planes are highlighted.

    The Periodicity Condition dialog box is updated.

  3. Click OK.

    The periodicity condition are now created and the specification tree is updated.

If you want to apply Periodicity Conditions via regular symmetry, open the sample43.CATAnalysis document from the samples directory.