advanced wb techniques.pdf

7/28/2019 Advanced WB Techniques.pdf

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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 lightweightversion of ANSYS.

By using Commands objects, you can access virtually

any ANSYS feature.

This advanced use of Workbench is the focus of thispresentation.


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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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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.

Import

Geometry

Assign

Materials

Review/Modify

Contact Regions

MeshControls

Apply

Loads / BCs

Solve

Review

Results

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.

Nodes

Elements

Materials

Contact Pairs

Loads

Postprocessing

Solution


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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 datafor 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

Solution Branch

Commands inserted here are placed

immediately after the /POST1 command.

Useful if you want to:

Postprocess analysis types not yet exposed inSimulation (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 theDetails region just like

other Workbench data.

ARG1-ARG9 can also be

flagged for parametric

studies just like any otherWorkbench 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 likeany 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 elementcomponents.

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.


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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 spoutand base.

Solution

First create named

selections to identify the

desired points.


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Ex 1: Custom Postprocessing

Solution (contd)

In a Commands object

under Solution, use APDL

to retrieve displacements

and calculate the desireddata.

By using the my_ prefix,

the output parameters are

displayed in the Details

region, where they areflagged 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 thepostprocessor.

Solution

First create a named

selection to identify the

area.


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Solution (contd)

Use a Commands object in

the Environment branch to

create and apply a tabular

load.


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Solution (contd)

Use a postprocessing

Commands object (Solution

branch) to plot element

pressures and store the ploton 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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Solution (contd)

Insert a Commands object

under Enviroment to obtain

PSD solution.

Notice the *ABBRcommand 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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Solution (contd)

Insert postprocessing

commands in the Solution

branch to plot 1 stresses

and displacements from thePSD analysis.

The SET command at the

end allows subsequent

modal postprocessing to be

completed.


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Questions?

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