Path) before running the ADAPT macro would restrict the file search to the ANSYS root directory and your current directory, reducing somewhat the possibility that the wrong file will be used.

No matter where they reside, the subroutines will be accessed only if you set KYMAC = 1 on the ADAPT command (Main Menu> Solution> Solve> Adaptive Mesh). See the Guide to User-Programmable Features for more information on user subroutines and the ANSYS Parametric Design Language Guide for more information on APDL.

3.3.3. Customizing the ADAPT Macro (UADAPT.MAC)

For those cases when you need to modify the ADAPT macro but are unable to do so via separate user subroutines, you can modify the main body of the macro.

To maintain the integrity of the ADAPT macro, ANSYS does not recommend modifying the ADAPT.MAC file directly. Instead, use the UADAPT.MAC file (an identical copy of ADAPT.MAC), provided on the ANSYS installation media.

If you modify the UADAPT.MAC file, it is a good idea to rename the modified file (especially to denote the specific version that you have created). Afterwards, instead of issuing the command ADAPT, call the modified adaptive meshing procedure by issuing the new file name.

Be aware that if you use the new file name as an "unknown command," the program will first search through the high-level directory, then through the login directory, and finally through the working directory, until the macro is found. If a modified adaptive procedure is to be accessible by a single user, it makes sense to store the file in a directory no higher than the user's login directory. If the macro file is stored in such a low-level directory, the file search can be streamlined by calling the macro using the

*USE command (Utility Menu> Macro> Execute Data Block) in place of the unknown command format.

3.4. Adaptive Meshing Hints and Comments

Use the following hints to enhance your implementation of adaptive meshing:

•No initial element sizes are required, but they may be specified to aid the adaptive convergence when desired. If you specify initial element sizes at keypoints, the ADAPT macro will use these sizes

in its first loop, and will adjust these sizes as appropriate in subsequent loops. To specify initial element sizes, use one of these methods:

Command(s): KESIZE

GUI: Main Menu> Preprocessor> Meshing> Size Cntrls> ManualSize> Keypoints> All KPs Main Menu> Preprocessor> Meshing> Size Cntrls> ManualSize> Keypoints> Picked KPs

If you specify line divisions or spacing ratios, the ADAPT macro will use these values in every loop. (That is, line divisions or spacing ratios that you specify will not be changed by the ADAPT macro.) If you do not specify mesh divisions of any kind, default element sizing (SMRTSIZE and DESIZE) will be used for the initial mesh. To specify line divisions or spacing ratios, use one of these methods:

Command(s): LESIZE

GUI: Main Menu> Preprocessor> Meshing> Size Cntrls> ManualSize> Lines> All Lines Main Menu> Preprocessor> Meshing> Size Cntrls> ManualSize> Lines> Picked Lines

•Mapped meshing (all quadrilaterals) is available for 2-D solid and 3-D shell analyses. The benefits of using mapped area meshing are usually minimal, however.

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•Mapped meshing (all hexahedral bricks) is available for 3-D solid analyses. Mapped volume meshing, if possible for a given model, will probably give superior performance, compared to tetrahedral meshing.

•In general, midside-node elements will perform better than linear elements in an adaptive meshing operation.

•Do not use concentrated loads or other singularities (such as sharp re-entrant corners), because the ADAPT procedure cannot show energy value convergence with mesh refinement in the vicinity of these singularities. If a concentrated loading condition is present in your model, replace it with an equivalent pressure load, applied over a small area. (Or, exclude the region of the concentrated load from adaptive modification using the select options discussed previously.)

•For many problems, it could be preferable to use a number of relatively small, simple regions in place of fewer large, complicated regions, for best meshing performance.

•If the location of maximum response is known or suspected beforehand, then a keypoint should be placed near that location.

•If the ADAPT procedure is used in an interactive run and the ANSYS program aborts abruptly without issuing the proper error message, then the output file for the adaptive meshing portion of your run (Jobname.ADPT) should be reviewed to determine the cause.

•Similarly, if the ADAPT procedure is used in a batch run, then Jobname.ADPT should be saved and examined in case of an abrupt abort.

•If a model has an excessive curvature in some region, then your model might experience mesh failure. In this case, use the SIZE field on the KESIZE command (Main Menu> Preprocessor> Meshing> Size Cntrls> ManualSize> Keypoints> Picked KPs) to define the maximum element edge length settings at keypoints near the excessive curvature region. FACMX should also be set equal to 1 (in

the ADAPT command) so that element size will not be permitted to grow in the vicinity of the excessive curvature.

•You should save the results file (Jobname.RST or Jobname.RTH). In case of a program abort in the middle of the ADAPT procedure, the results file will still have the entire analysis data from the previous solution completed by the ADAPT procedure.

•You should issue a SAVE (Utility Menu> File> Save as Jobname.db) before starting the adaptive meshing operation. In case of system abort, Jobname.DB can then be used to restart the analysis.

3.5. Where to Find Examples

The Mechanical APDL Verification Manual describes several analyses that demonstrate adaptive meshing.

The Mechanical APDL Verification Manual consists of test case analyses demonstrating the analysis capabilities of the ANSYS program. While these test cases demonstrate solutions to realistic analysis problems, the Mechanical APDL Verification Manual does not present them as step-by-step examples with lengthy data input instructions and printouts. However, most ANSYS users who have at least limited finite element experience should be able to fill in the missing details by reviewing each test case's finite element

model and input data with accompanying comments.

The Mechanical APDL Verification Manual contains the following adaptive meshing test cases:

VM193 - Adaptive Analysis of 2-D Heat Transfer with Convection

VM205 - Adaptive Analysis of an Elliptic Membrane Under a Uniformly Distributed Load

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