Ansys License Check

[Stefanie Mordaunt]

Activateselement shape checking. New elements, regardless of how they are created, are tested againstexisting warning and error limits. (The existing limits may be thedefault limits, or previously modified limits.) Elements that violateerror limits produce error messagesand either (a) cause a meshing failure, or (b) for element creationor storage other than AMESH or VMESH, are not stored. Elements thatviolate warning limits produce warning messages. If shape checking was previously turned off [SHPP,OFF] and you turn it on, existing elements are markedas untested; use the CHECK command to retest them. With this option, you may also specify a value for VALUE1 to turn individual shape tests on. If you do not specify a valuefor VALUE1, all shape tests are turnedon.

Activates element shape checking;however, in contrast to SHPP,ON, elements thatviolate error limits do not cause either a meshing or element storagefailure. Instead, they produce warning messages to notify you that error limits have been violated. Thisoption does not alter current shape parameter limits. Since the defaultshape parameter error limits are set to allow almost any usable element,the elements this option allows, which would otherwise be forbidden,are likely to be very poorly shaped.

Deactivates element shape checking. This setting does not alter current shape parameter limits. Useof this option is risky, since poorly shaped elements can lead toanalysis results that are less accurate than would otherwise be expectedfor a given mesh density. With this option, you may also specifya value for VALUE1 to turn individual shapetests off. If you do not specify a value for VALUE1, all element shape tests are turned off.

Lists the shape parameter limitscurrently in effect, along with status information about element shapechecking (for example, whether any individual shape tests are off,whether any of the shape parameter limits have been modified, andso on).

Resets element shape parameterlimits to their default values. Also, if any individual tests wereturned off, turns them back on. (The SHPP,DEFAULTcommand may be useful if any parameter limits were previously alteredby using the MODIFY option.)

Determines whether element shapetest results data is stored in memory. When this option is turned on, an "object" is created for storingtest results in memory. When this option is turned off, no objectis created and no data is stored; thus, any operation that requiresshape parameters for an existing element (such as use of the CHECK command) causes the shape parameters to be recomputed. (Note the distinction between storing the data in memory and storingit in the database; regardless of whether this option is turned onor off, no element shape test results data will be stored in the database. The element shape parameter object is deleted automatically beforeany solution.) This setting is independent of shape checking status,with one exception--if shape checking is turned off [SHPP,OFF], the object is not created. Keep in mind that recomputingshape parameters is more computationally expensive than retrievingthem from the object. With this option, you must also specify a valuefor the VALUE1 argument; the VALUE2 argument is ignored.

Determines, for Jacobian ratio tests,whether sampling is done at integration points (DesignSpace product method),or at corner nodes. When this option is turned on, sampling is doneat integration points, and the default limits for h-element Jacobianratios are a warning tolerance of 10 and an error tolerance of 40.When this option is turned off, sampling is done at corner nodes,and the corresponding default limits are a warning tolerance of 30and an error tolerance of 1000. Sampling at the integration points(option on) results in a lower Jacobian ratio, but that ratio is alsosubjected to a more restrictive error limit. Some elements that havepassed the integration point sampling criterion, have failed the cornermode sampling criterion. Because of this, use integration point samplingonly for simple linear analyses. For other types of analyses (e.g.,nonlinear, electromagnetic), use sampling at corner nodes, which isthe more conservative approach. With this option, you must also specifya value for the VALUE1 argument; the VALUE2 argument is ignored.

Valid for the MODIFY and FLAT options only. When Lab = MODIFY, specifies the new limit for the shapeparameter that is in the location indicated by the VALUE1 argument. See the examples in the Notes section. When Lab = FLAT, VALUE2 is the error limit. The default is 1.0e-2.

The following examples illustrate how to use the SHPP,MODIFY,VALUE1,VALUE2 command to respecify shape parameter limits. Assume that you issuedthe SHPP,STATUS command, and you received the outputbelow:

Notice that in the sample output, the warning tolerance for aspect ratios is set to 20. Nowassume that you want to "loosen" this shape parameter limit so thatit is less restrictive. To allow elements with aspect ratios of upto 500 without causing warning messages, you would issue this command:

Also notice that each shape parameter's numeric location withinthe shape parameter limit array appears in the sample output withinparentheses. For example, the numeric location of the aspect ratioshape parameter (for warning tolerance) is 1, which is why "1" isspecified for the VALUE1 argument in theexample command above.

Now notice that the sample output indicates that any triangleelement with an internal angle that is greater than 179.9 degreeswill produce an error message. Suppose that you want to "tighten" this shape parameter limit, sothat it is more restrictive. To cause any triangle or tetrahedronwith an internal angle greater than 170 degrees to produce an errormessage, you would issue this command:

The existence of badly shaped elements in a model may lead tocertain computational errors that can cause your system to abort duringANSYS solution. Therefore, you run the risk of a system abort duringsolution any time that you turn element shape checking off entirely,run shape checking in warning-only mode, turn off individual shapechecks, or loosen shape parameter limits.

Since the shape parameter limit array was completely reorganizedat ANSYS 5.4, you should revise any input files created prior to 5.4that contain limit changes so that they reflect the reorganized datastructure.

After you have set up your case, and prior to solving it, you can check your case setup using the Case Check dialog box (Figure 26.17.1). This function provides you with guidance and best practices when choosing case parameters and models. Your case will be checked for compliance in the mesh, models, boundary and cell zone conditions, material properties, and solver categories. Established rules will be available for each category, with recommended changes to your current settings. At your discretion, you may elect to apply the recommendations, or keep your current settings. To access the Case Check dialog box (Figure 26.17.1), go to Run Calculation Check Case... If there are no problems with your case setup, then an information dialog box (Figure 26.17.2) will appear stating that no recommendations need to be made at this time, otherwise, the Case Check dialog box will open.

SDC for Ansys is a structural verification software that works on top of Ansys Mechanical. It has a built-in engineering standards library to easily perform fatigue, buckling, welds, bolts and custom design checks according to various industry codes and regulations. SDC for Ansys has specially designed Recognition tools for automatic detection of welds, beams, plates and connections (joints).

The Optimization module helps to make the best possible design decision based on the code check results. Optimization can be based on cross-section, weld type, yield stress and plate thickness parameters.

Reports in SDC for Ansys are template-based and contain all calculated results presented as plots and tables. In case of any changes in the calculation process, all results can be regenerated with one click.

Ansys Workbench Mechanical supports the presence of APDL commands in the Outline so that user-programmed commands will act on a model at the Body, Connection, Solver or Postprocessing stage of an Ansys job running from the ds.dat file generated by the Mechanical SOLVE command.

This article illustrates how to use APDL commands to detect the UNITS that are active when SOLVE is requested for an environment in Workbench Mechanical. The check could be included at the beginning of any APDL Commands Object in Workbench that assumes the UNITS employed in a SOLVE.

It is easy to have the wrong UNITS chosen when Workbench Mechanical SOLVE executes, for a Commands Object that assumes a particular system of units. Consider a material property in a Commands Object using the BIN system of units (lb-in-sec), but UNITS in Workbench Mechanical set to SI. If an APDL Commands Object assumes units during SOLVE for loads, material properties, contact settings, or makes other units-related assumptions during customized pre- or post-processing, it is critical to use the correct system of units.

The following script example checks the Units setting in a Workbench Mechanical solution run, and works because the /UNITS command is executed by the Ansys input APDL job ds.dat file that Workbench Mechanical creates. The following code snippet can be added at the beginning of any existing Commands Object, or placed in its own Commands Object in the Project tree, typically at the Environment level. Its purpose is to stop the run if the desired Units are not employed in that Environment. It can be customized as desired:

Users need to be very careful with thermal property units in a Commands Object if they are not employing SI units throughout a model. Invalid results will be less likely if SI units are employed in such thermal models when they include units-dependent APDL Commands Objects.

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