AdvancedANSYS Workbench

Techniques

Presented At

Midwest ANSYS User Group

Fall 2005 Meeting

By

Krishna S. Raichur

Belcan Engineering Group

Downers Grove, IL

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What is Workbench?

• A unified working environment for:– Importing CAD geometry

– Preparing models for analysis (DesignModeler)

– Performing FEA simulations (Simulation)

– Optimizing designs (DesignXplorer or DesignXplorer VT)

ANSYS Workbench

DesignModeler Simulation DesignXplorer

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… What is Workbench?

• Other modules included in Workbench:– Engineering Data – a material data repository

– FE Modeler – to read and write NASTRAN and ABAQUS models

– CFX-Mesh – to prepare meshes for CFX-5

• For most ANSYS users, “Workbench” is usually synonymous with the Simulation module of Workbench.

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… What is Workbench?

• The Simulation module in WB is built around core ANSYS technology.– Not all ANSYS capabilities have been “exposed” yet in

Simulation, but it is certainly not a “lightweight” version of ANSYS.

– By using Commands objects, you can access virtually any ANSYS feature.

• This “advanced” use of Workbench is the focus of this presentation.

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Why Use Workbench?

• There are many compelling reasons to use WB. Here are the top five:– Geometry Import

• Tremendous savings in time…

– CAD Associativity• Easy to make geometry changes, update the simulation, and

compare to previous scenario…

– Automatic Contact Detection• Hundreds of contact pairs are detected within seconds!

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… Why Use Workbench?

• Top 5 reasons (cont’d):– Robust Meshing

• Can tolerate imperfect geometry• Hex-dominant meshes• Gap meshing tool for field analyses

– “They wrote a macro for it!”• Bearing loads• Compression-only support• Force on area, moments on solids• Etc.

• See also the Oct 2005 issue of PADT’s The Focus publication.

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Simulation Work Flow

• First step in learning the use of commands in WB is to understand the overall work flow.

• Pressing Solve button in Simulation creates an APDL input file, ds.dat, in the solver working directory.– This is what enables the use

of commands.

ImportGeometry

AssignMaterials

Review/ModifyContact Regions

MeshControls

ApplyLoads / BC’s

Solve

ReviewResults

Batch Solution

XMLResults File(s)

ds.dat File

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The ds.dat File

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…The ds.dat File

• Contains preprocessing, solution, and postprocessing commands.

NodesElements

Materials

Contact Pairs

Loads

PostprocessingSolution

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Commands Objects

• You can have your own commands included in ds.dat by inserting Commands objects in the tree outline.

• Geometry Branch– You can insert Commands for each part.

– Useful if you want to:• Change element type or keyoptions

• Change material properties

• Change real constants (such as to add data for composites)

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… Commands Objects

• Contact Branch– Insert Commands for each contact region.

– Useful if you want to change or add contact options not yet exposed in Simulation (Keyopt(7), for example).

• Mesh Branch– No Commands allowed

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… Commands Objects

• Environment Branch– Commands inserted here are placed just

above the SOLVE command in ds.dat.

– Useful if you want to:• Apply tabular loads

• Add coupling or constraint equations

• Do analysis types not yet exposed in Simulation (PSD, response spectrum, etc.)

• Change load step options – solution controls, convergence criteria, etc.

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… Commands Objects

• Solution Branch– Commands inserted here are placed

immediately after the /POST1 command.

– Useful if you want to:• Postprocess analysis types not yet exposed in

Simulation (PSD, response spectrum, etc.)

• Add your own postprocessing, such as unaveraged stress plots, path plots, and surface operations

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… Commands Objects

• Input Arguments– Up to 9 input arguments are

allowed on all Commands objects.

– Values can be entered in the Details region just like other Workbench data.

– ARG1-ARG9 can also be flagged for parametric studies just like any other Workbench input data.

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… Commands Objects

• Output Parameters– For Commands objects at

the Solution level, Workbench scans for parameters with a user-specified prefix (“my_” by default) and reports their values in the Details region.

– Can be flagged for parametric studies just like any other Workbench output data.

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Named Selections

• The ds.dat file contains no solid model data, only nodes and elements.

• Named Selections are useful to identify entities when using commands.

• Example:– To apply a tabular (non-uniform) pressure

load on the highlighted area, we give the area a name (“InnerFace” in this example).

– When Workbench creates ds.dat, it will put all nodes on that area into a nodal component called INNERFACE.

– The commands to apply the tabular load can then use this nodal component.

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… Named Selections

• Named solid bodies (volumes), surface bodies (shells), and line bodies (beams) are written to ds.dat as element components.

• Named faces (areas), edges (lines), and vertices (keypoints) are written as nodal components.

• By naming all entities required for command processing, you can eliminate the need for solid model data.

Examples

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Ex 1: Custom Postprocessing

• Requirement– Under a series of given

loads, calculate the diameter at “Spout_PtX” and the gap between spout and base.

• Solution– First create named

selections to identify the desired points.

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… Ex 1: Custom Postprocessing

• Solution (cont’d)– In a Commands object

under Solution, use APDL to retrieve displacements and calculate the desired data.

– By using the “my_” prefix, the output parameters are displayed in the Details region, where they are flagged for a parametric study.

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Ex 2: Tabular Loading

• Requirement– Apply a tapered pressure

load on the inner face of a tube and verify with a pressure plot in the postprocessor.

• Solution– First create a named

selection to identify the area.

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… Ex 2: Tabular Loading

• Solution (cont’d)– Use a Commands object in

the Environment branch to create and apply a tabular load.

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… Ex 2: Tabular Loading

• Solution (cont’d)– Use a postprocessing

Commands object (Solution branch) to plot element pressures and store the plot on a .png file.

• The requested plot shows under the Commands branch as “Post Output.”

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Ex 3: Random Vibrations (PSD)

• Requirement– Do a PSD analysis in

Workbench.

• Solution– Create a named selection of

supports (required later in PSD analysis).

– Do a modal analysis (required step for any dynamic analysis).

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… Ex 3: Random Vibrations (PSD)

• Solution (cont’d)– Insert a Commands object

under Enviroment to obtain PSD solution.

– Notice the *ABBR command at the end of the PSD input.

• This disables the SOLVE command in ds.dat, but allows subsequent postprocessing commands to be executed.

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… Ex 3: Random Vibrations (PSD)

• Solution (cont’d)– Insert postprocessing

commands in the Solution branch to plot 1 stresses and displacements from the PSD analysis.

– The SET command at the end allows subsequent modal postprocessing to be completed.

Questions?