Submodeling in ANSYS WorkBench 14.5 - ESSS

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Submodeling in ANSYS WorkBench 14.5. Roberto Silva. ESSS ... Submodeling procedure. • Using submodeling in WorkBench Mechanical 14.5 ... Page 12 ...
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 cutboundary limits. – Submodel boundary must be far from critical regions.