Applying coupling and rotation

Estimated time to complete: 15–25 minutes

In this tutorial, you will learn how to use the Automatic Coupling command.

1: Setup

  1. On your desktop or the appropriate network drive, create a folder named impeller2.

  2. Click the link below:

    Download the part

  3. Extract the file to your impeller2 folder.

  4. Start Simcenter 3D or NX.

  5. Open impeller_sim1.sim.

2: Reset dialog box memory

The options you select in dialog boxes are preserved for the next time you open the same dialog box within a given session. Restore the default settings to ensure that the dialog boxes are in the expected initial state for each step of the activity.

File

Preferences→User Interface

  • Options

  •   Reset Dialog Memory

  • OK

     
3: Define the global cyclic CSYS as the nodal displacement CSYS

In this cyclic symmetric analysis, the solid body of the impeller has been trimmed to a single blade. In the supplied FEM, a 2D mesh dependency on the symmetry faces was used to seed the 3D solid mesh. It also includes a global cyclic coordinate system, a cylindrical coordinate system whose Z-axis defines the default axis of rotation for the FEM.

You will assign the global cyclic coordinate system that was defined for the FEM as the nodal displacement coordinate system.

  Menu 

  • Edit→Node→Assign Nodal Coordinate System

  • Type Filter (Top Border bar)

    Polygon Body

  •  

  • CSYS

    Global Cyclic Analysis

  •  

     

  •   Interior and Boundary Nodes

  • OK

     
4: Add a fixed translation constraint

  Fixed Translation Constraint (Home tab→Loads and Conditions group→ Constraint Type list)

  • Rotate the model to view the underside.

  • Type Filter (Top Border bar)

    Polygon Face

  •        

  • OK

     

     

5: Couple the DOF of node pairs

Couple the degrees of freedom (DOF) for each pair of equivalently positioned nodes lying on the repeated faces.

 Automatic Coupling (Loads and Conditions group→ Constraint Type list)

  •  

  •   Independent (Select Object)

  •  

  • Tip:

    Use QuickPick to select the polygon vertex.

  •  

     

  •   (the polygon vertex)

  •  

     

  • Type

    Global Cyclic Analysis

  •  

     

  • DOF1

    On

    DOF2

    On

    DOF3

    On

  • OK

     

  •  

6: Resize the constraint symbols

The constraint symbols have a large default size and may clutter your display. Reduce the size of the symbols.

  Simulation Navigator

  •   Constraint Container

  •   NoTrans(1)

  • Ctrl

     +   Automatic Coupling(1)

  •   Edit Display

  • Scale

  • Drag toward Tiny.

  • OK

     

  •  

7: Consider the conflicting constraints

Coupling the DOF of node pairs created a constraint that conflicts with the fixed translation constraint. The conflict occurs along the four edges of the model shared by the dependent face of the coupling constraint and the faces that have the fixed translation constraint. In the illustration, these edges are shown in orange.

If you attempt to solve this model, the conflicting constraints would cause the solve to terminate.

You can resolve the conflicting constraints by excluding the edges where the conflicting constraint occurs from the fixed translation constraint. The nodes on the excluded edges will still be fixed because they are coupled to fixed nodes on the independent face.

8: Determine the dependent side of the coupled constraint

The independent and dependent faces were determined when the 2D dependent mesh was created.

  • is the independent face

  • is the dependent face

9: Edit the fixed translation constraint

Edit the fixed translation constraint to exclude the edges with the conflicting constraint condition.

  Simulation Navigator

  •   Constraint Container

  •   NoTrans(1)

  •   Edit

  •  

     

  •   Excluded (Select Object)

  • Type Filter (Top Border bar)

    Polygon Edge

  •       

  • OK

     

The fixed translation constraint no longer exists on the edges that are excluded. By selecting the fixed translation constraint in the Simulation Navigator, you can zoom in and see that the constraint symbols are no longer applied along the excluded edges.

10: Apply a rotation load

  Rotation (Loads and Conditions group→ Load Type list)

  • Type

    Whole Model

  •  

     

  • If necessary:

    Axis of Rotation

    Global Cyclic Analysis

  •  

     

  • Angular Velocity

    10000 rev/min2
    Note:

    Make sure that you use the correct units.

  • OK

     

  Save

11: Solve the model

  Simulation Navigator

  •   Solution 1

  •   Model Setup Check

  • In the Information window, note the recommendation to use the iterative solver.

  •   the Information window

  •   Solution 1

  •   Edit

  • General

  •   Element Iterative Solver

  • OK

     

  •  

      Solution 1

  •   Solve

  • OK

     

  •  

    Wait until the solve is complete.

  • No

     Review Results dialog box

  •   the Information window

  • Cancel

     Analysis Job Monitor dialog box

12: Display the results

  Simulation Navigator

  •     Solution 1→Results

  •   Structural

 

  Post Processing Navigator

  •   Solution 1→Structural→Displacement – Nodal

      Magnitude

  Save

After viewing the displacement magnitude results, try displaying the Von Mises results under Stress - Element-Nodal.

 

File

  • Close→All Parts