ModelChecker – What does this software do?

It provides a menu-driven (or batch), automatic, comprehensive assessment and documentation of any ANSYS® structural model before the model is analyzed or solved.

ModelChecker – Why should I use it?

· To thoroughly document the model

· To increase the reliability of all models, guarantees that every model has been reviewed/checked at a rigorous level

· To decrease the model debugging effort

· To eliminate solutions that produce incorrect results

· To minimize the number of solution runs

· To ensure there are no gross modeling mistakes

· To evaluate outsourced models

· To exchange FE model information anywhere, worldwide

· To minimize the support burden that inexperienced users place on expert users

· To educate inexperienced users in the creation of correct models

ModelChecker – When do I use it?

You can use MC at any time during the modeling process. You may want to use it sequentially to provide information about the solid model, the element and attribute settings, the quality of the finite element mesh, and the applicability of the types of loadings and solver settings. In general, you will obtain the most benefit by using MC during and after model building.

ModelChecker – What features of ANSYS® are supported?

All current structural element types, their key options, all materials (linear and nonlinear), real or geometric constants, all nonlinear geometric and contact behavior, all special forms of model attachment using constraint equations and coupling, all possible applied loads and boundary conditions, and all solution settings are considered.

ModelChecker – What hardware platforms are supported?

MC appears in the ANSYS® graphical user interface as a Main Menu selection and, therefore, runs on all the ANSYS® supported hardware platforms.

ModelChecker – What type of results or output does it produce?

MC issues a comprehensive HTML report that can be viewed using any Web browser. This report is written to a directory named JOBNAME_RPT. This directory is located below the user’s working directory.

ModelChecker – Does it change or correct my model?

MC is a diagnostic tool, not a repair tool. MC does not attempt to change any features of the model that are causing warnings. In many cases, the warnings simply alert/remind the user of model characteristics that were actually intended and that are not real modeling errors or causes of concern.

Users are expected to make a backup copy of their database before running their models through MC. MC attempts to leave the database unchanged, except for the creation of parameters and components. However, there is always the possibility that an inadvertent change has occurred. MC must modify and then restore certain aspects of the model if any of the following characteristics are present in the database.

The number of substeps is greater than one and load or mass summary is requested, MC issues the command NSUBST,1,1,1, runs the load and mass summary, and then reissues the NSUBST command with the original settings. This ensures that the loads in the load summary are the loads at the end of the loadstep.

Thermal loads (temperatures) are applied to the model and load or mass summary is requested, MC writes the material properties to a file using the command MPWRITE, deletes the coefficients of thermal expansion (ALPX, etc.), runs the load and mass summary, and then restores the original material properties (from the file) using the command MPREAD. This avoids the possibility of spurious thermal loads (which should balance exactly to zero) in the load summary.

· Unsupported element types (by MC) are in the database and a load or mass summary is requested, MC sets these element types to NULL (element type 0), runs the load and mass summary, and then reissues the required ET commands to redefine the original element types and their key options. This modification is needed since we have seen errors in MC (not ANSYS®) structural loads and mass when such element types are in the database.

If you intend to use the same database (used by MC) for your analysis, by all means double-check these items. In general, we recommend (we also wear belts and suspenders) that you make any required changes to the model using the backup copy of the database (not used by MC), this is the only method that ensures that MC has not, inadvertently, caused any model changes.

ModelChecker – Can ModelChecker be customized?

There are several variables (known as ANSYS® parameters) that have been made available for customization. These variables can be used to control the quantity of checking performed as well as the amount of information written to the HTML report or saved as components. They are discussed throughout this manual and detailed further in Appendix B.

Note: MC creates user-defined parametric variables and other variables during the model check. All variable names created by MC, with four exceptions, begin with the “_” character. The four exceptions are the arrays caegsc_, caegch_, caegms_, and caegls_. These array variables contain most of the model, mass, and load information. If MC defines a parameter that is currently defined in the model database, it will be overwritten. To list the currently defined underscore variables, in the ANSYS® Input Window, type the command *STATUS, _prm. Users should avoid the use of such parameter names. MC also defines components with names beginning with “caeg”. Users should also avoid naming components or assemblies beginning with the letters “caeg”.

MC can be easily installed on any computer platform including all UNIX and Windows networked systems or standalone installations. There are no compiler requirements or installation language prerequisites. Please refer to the section Installing ModelChecker for proper placement of the module granule and macro components.

The module appears as a menu selection in the Main menu of the ANSYS® Graphical User interface. Subsequent Dialog boxes allow you to select your desired model evaluation checks. The available selections will be discussed in the Model Checking Options section of this manual.