Multistage cyclic symmetry requires the application of cyclic symmetry and interstage constraints, in addition to any other user-defined constraints. These two distinct groups of boundary conditions, cyclic and interstage, must be enforced to correctly model the base structure physics. You apply these constraints using the multistage commands (MSOPT plus CECYCMS and CEIMS).

The multistage procedure differs from the cyclic symmetry procedure (initiated with CYCLIC) in that it does not create or modify cyclic or interstage constraint equations during solution. This enables you to conveniently view and check constraints before or after solution. You can issue MSOPT,LIST to view the interstage constraint equations or CELIST to list any constraint equations selected, including cyclic symmetry boundary conditions. With stage cloning, the number of visible constraints that appear at the same location can be quite large, and it may be necessary to select individual stages or clones (MSOPT,LIST,Sname,1 to obtain NEQN1 and NEQN2 then CELIST,NEQN1,NEQN2) to check if the constraints are effectively applied to the correct degrees of freedom for particular stages.

Applying additional constraints or boundary conditions (other than multistage cyclic and interstage constraints) at the cyclic or interstage boundaries is not recommended with one exception: you can fix all degrees of freedom on the cyclic boundaries using D,ALL,ALL.

More details on loading in a multistage static analysis can be found in the analysis procedures described in Static Loading.

The application of cyclic and interstage constraints are described in this chapter and illustrated in workflow diagrams of a representative multistage cyclic symmetry analysis (Multistage Analysis Procedure Flow Diagrams).