ansys shrt courses

7/29/2019 Ansys Shrt Courses

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ANSYS Short Course 1

ANSYS Short Course

Tim Langlais


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Intro to ANSYS

Problems ANSYS can solve

y Static Structures

y

Harmonic, Vibrationy Electromagnetics

y Dynamics

y Fluids


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Schedule

1. 2D Structural Example

2. 2D Thermal Example

3. Batch Processing

4. Modeling

5. Meshing

6. Solution

7. Post Processing

8. Tips and Tricks


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Getting Started

Copy the course materials to your directory and start ANSYS:unix% cd ~

unix% cp ~langlais/ansys-course.tar.gz .

unix% gunzip ansys-course.tar.gz

unix% tar -xvf ansys-course.tar

unix% cd ansys/batch

unix% module add ansys

unix% ansys54 -g -p ansysrf


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Help!

ANSYS Home http://www.ansys.com

Online ManualsUtility Menu

Help

Net Manuals

http://terminator.tamu.edu/softwareDocs/ansys/realtoc.html


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2D Structural Example

1000N

0.002R

0.02m

0.02m

y plane stress

y model in 2D


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2D Thermal Example

T=25C

T=200C 0.02m

T=50Ck=20W/mK

0.02m

0.002R

2

h=150W/m K2

q= -100W/m

y model in 2D


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What is a Batch File?

A batch file is an ASCII file that contains a list of ANSYS

commands used to define a problem.

y all GUI commands are tied to batch commands

y batch files can be run interactively or in the background


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Disadvantages of Batch Processing

y must learn new command set

y learning curve is steep


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Advantages of Batch Processing

y saves space! 20K batch file vs. 30MB *.db file

y parametric modelingcan change parameters and re-run

y can run analyses in the background

Batch processing saves time, especially if you need to analyze

something repeatedly. It is possible to automatically vary certain

parameters and keep track of the results!


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ANSYS Batch Language

y primitive FORTRAN syntax

y can make loops and conditionals based on any variable

Uses:

y selective application of boundary conditions

y calculation based on results

resultant force at boundary

average temperature over a surface


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Modeling Exercise: Notched Shaft

2.25"1.0"

0.15"R

1.0"1.5"

y fillet is 90o arc

y circular cross-section


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ANSYS and Pro/E

y no elegant way to read Pro/E files in ANSYSyet

Option 1:

y mesh within Pro/E using Pro/FEA

y export ANSYS file from Pro/E

y read file into ANSYS

Option 2:

y export IGES file from Pro/E

y import IGES file into ANSYS

y mesh within ANSYS


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Meshing

Free Meshing

y use ANSYS MeshTool with the Smart Mesher

y can automatically mesh any geometry

y difficult to control element shape

Mapped Meshing

y easy to control element shapes and sizes

y can lead to more accurate results

y more difficultneed to split areas and volumes a certain way


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Example Free Mesh


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Example Mapped Mesh


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Solution

y different solvers for different problemsmake sure you use the

right one!

ymake sure you know the DOFs of your element before applyingthe BCs

y for structural problems, remember to distribute loads over

several nodes


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Post Processing

y contour plots using Plot Results > Nodal Solu ... or

Element Table

y line plots using Path Operations >

y print plots using PlotCntrls -> Hard Copy ...


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Tips and Tricks: Files

For linear, static problems ANSYS solves

Ax = b

During solution, ANSYS writes equation to disk, creating lots of

large temporary files.

y as long as you have saved everything (SAVE_DB), the *.db file is

the only one you need

y the *.rst, *.emat, *.esav, etc. are not needed


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Tips and Tricks: More Files

Because ANSYS writes large temporary files to disk during solution,you should not run your analysis in your home directory (because

you will be writing over the network).

y unix% cd /usr/tmp/ these are temporary directories on the

local hard drive

y once solution is done, copy batch file and/or *.db file to your

home directory

Solution is much faster this way!


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Tips and Tricks: Memory Allocation

ANSYS is a resource hog.

y out of local memoryANSYS cannot allocate enough memory

on this machine

run on another machine

y out of heap space

tell ANSYS to allocate more space using -m or -db switch

y disk fullyou are over quota

use scratch space in /usr/tmp/

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