Submodeling in ANSYS WorkBench 14.5

Roberto Silva

ESSS

TOPICS

• What is submodeling?

• Submodeling procedure

• Using submodeling in WorkBench Mechanical 14.5

• Comparison with Mechanical APDL submodeling

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.

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

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.

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.

SUBMODELING PROCEDURE

• Create and solve the global model;

• Create the submodel;

• Apply cut-boundary interpolation;

• Solve the submodel;

• Verify results and cut boundary position.

SOLVING THE GLOBAL MODEL

• No special setup for global model.

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

CREATING THE SUBMODEL

• A Submodeling folder is automatically created, that

allows the definition of applied load.

– Loads must be applied on cut-boundary.

CREATING THE SUBMODEL

• Several options are similar to External Data.

– Display Source Points

– Mapping Controls

– Rigid Transformation

CREATING THE SUBMODEL

• Loads must be reapplied to submodel!

Pressure = 10 MPa

Force = 10 N

Pressure = 10 MPa

Force = 2.5 N

RESULTS VERIFICATION

• Submodel with same mesh size.

RESULTS VERIFICATION

• Submodel with more refined mesh size.

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

SUBMODEL – GEOMETRIC DETAILS

• Example: pressure vessel with nozzle.

Weld fillets were

inserted in submodel

SUBMODEL – GEOMETRIC DETAILS

• Mesh comparison

61 126 nodes

30 101 elements

188 239 nodes

40 651 elements

SUBMODEL – GEOMETRIC DETAILS

SUBMODEL – GEOMETRIC DETAILS

Weld Region

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

SUBMODEL – 2D to 3D

• Cut-boundary surfaces must include the original 2D

model faces.

Both revolution section

faces must also be selected!

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

SUBMODEL – 2D to 3D

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…

WORKBENCH x MECHANICAL APDL

– … but it can be done with an ACT extension!

Available at ANSYS Customer Portal for download!

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.