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ANSYS Short Course

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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, Vibration
       y 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 Manuals Utility Menu → Help
      Net Manuals
          http://terminator.tamu.edu/softwareDocs/ansys/realtoc.html
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                        2D Structural Example


                                  0.002R


                                           0.02m



                              0.02m



                                 1000N


       y plane stress
       y model in 2D
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                              2D Thermal Example
                                   h=150W/m 2
                                            K
                                     T=25C


                                             0.002R
                               k=20W/mK                  T=50C

                     T=200C                                      0.02m

                                          q= -100W/m 2

                                     0.02m



       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 modeling—can 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
                                         0.15"R

                        1.5"                      1.0"


                                  1.0"   2.25"
       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 ANSYS—yet
      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 difficult—need 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 problems—make sure you use the
         right one!
       y make sure you know the DOFs of your element before applying
         the 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 memory—ANSYS 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 full—you are over quota
          « use scratch space in /usr/tmp/

				
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