Submodeling - Ansys

1. Submodeling in ANSYS WorkBench 14.5
Roberto Silva
ESSS

2. TOPICS
• What is submodeling?
• Submodeling procedure
• Using submodeling in WorkBench Mechanical 14.5
• Comparison with Mechanical APDL submodeling

3. WHAT IS SUBMODELING?
• Submodeling is a modeling approach that allows to
solve a small part of a bigger model, with more
refined meshes and results.

4. WHAT IS SUBMODELING?
• Submodeling is based on St. Venant’s Principle.
– Far away from loading regions and constraint boundaries,
mechanical behavior is not affected.
– If submodel boundaries respect this principle, good
results are obtained.
http://pl.wikipedia.org/wiki/Plik:Zasada_de_Saint-Venanta.jpg

5. WHAT IS SUBMODELING?
• This technique allows an initial evaluation of a
coarser (and faster to solve) global model, followed
by a detailed analysis of regions of interest.
• The smaller submodel geometry allows one to:
– Use a more refined mesh at the critical regions to provide
better results;
– Include small geometric details (like welds) that are not
represented in the global model.

6. WHAT IS SUBMODELING?
• Submodeling has been available in Mechanical
APDL for years!
– NWRITE, CBDOF…
• WorkBench users needed to use
• It’s now available directly in Workbench Mechanical
14.5 interface.

7. SUBMODELING PROCEDURE
• Create and solve the global model;
• Create the submodel;
• Apply cut-boundary interpolation;
• Solve the submodel;
• Verify results and cut boundary position.

8. SOLVING THE GLOBAL MODEL
• No special setup for global model.

9. CREATING THE SUBMODEL
• To create a submodel analysis, Solution from Global
model is connected to Setup of the submodel.
Available in
Static Structural and
Steady-State Thermal
Analyses

10. CREATING THE SUBMODEL
• A Submodeling folder is automatically created, that
allows the definition of applied load.
– Loads must be applied on cut-boundary.

11. CREATING THE SUBMODEL
• Several options are similar to External Data.
– Display Source Points
– Mapping Controls
– Rigid Transformation

12. CREATING THE SUBMODEL
• Loads must be reapplied to submodel!
Pressure = 10 MPa
Force = 10 N
Pressure = 10 MPa
Force = 2.5 N

13. RESULTS VERIFICATION
• Submodel with same mesh size.

14. RESULTS VERIFICATION
• Submodel with more refined mesh size.

15. SUBMODEL – GEOMETRIC DETAILS
• The submodel geometry can be different from the
global model!
– As long as cut-boundaries are far away from region of
interest.
• This allows the user to include some geometric
details that are not considered in the global model.
– Welds
– Small fillets and chamfers
– Defects, like dents and cracks

16. SUBMODEL – GEOMETRIC DETAILS
• Example: pressure vessel with nozzle.
Weld fillets were
inserted in submodel

17. SUBMODEL – GEOMETRIC DETAILS
• Mesh comparison
61 126 nodes
30 101 elements
188 239 nodes
40 651 elements

18. SUBMODEL – GEOMETRIC DETAILS

19. SUBMODEL – GEOMETRIC DETAILS
Weld Region

20. SUBMODEL – 2D to 3D
• WorkBench submodeling can also be used to read
results from a 2D analysis in a 3D model.
2D Axisymmetric model 3D model

21. SUBMODEL – 2D to 3D
• Cut-boundary surfaces must include the original 2D
model faces.
Both revolution section
faces must also be selected!

22. SUBMODEL – 2D to 3D
• It’s necessary to select a cylindrical coordinate
system, aligned with the original plane.
2D Y-axis = 3D Z-axis
2D X-axis = 3D X-axis

23. SUBMODEL – 2D to 3D

24. WORKBENCH x MECHANICAL APDL
• PROS:
– User-friendly operation – No manual file handling!
– No need of APDL commands.
– Global mesh data can be adjusted – no need to worry
about origin position!
• CONS:
– No shell-to-solid submodeling yet…

25. WORKBENCH x MECHANICAL APDL
– … but it can be done with an ACT extension!
Available at ANSYS Customer Portal for download!

26. SUBMODELING FINAL REMARKS
• Submodeling is an useful technique to study large
structures in detail.
– Optimizes mesh refinement;
– Optimizes geometric detail modeling.
• The user must be careful to define suitable cut-
boundary limits.
– Submodel boundary must be far from critical regions.