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Nonstandard Uses of the ANSYS Program

 

 

 

 

 

User-Programmable Features Available in ANSYS

 

 

 

 

 

 

User-defined contact

The contact elements (CONTA171 to CONTA178) allow you to define your own

 

interfacial behaviors

interfacial behaviors between surfaces. See Subroutines for Customizing Contact

 

 

Interfacial Behavior in the Guide to User-Programmable Features.

 

User real constants

Elements COMBIN37, CONTA171, CONTA172, CONTA173, CONTA174, CONTA175,

 

 

CONTA176, CONTA177, and CONTA178 allow the input real constants to be

 

 

modified based upon your own nonlinear function.

 

User thickness

Available for SHELL181, SHELL208, SHELL209, and SHELL281.

 

User stresses

Available for LINK180, SHELL181, PLANE182, PLANE183, SOLID185, SOLID186,

 

 

SOLID187, SOLSH190, BEAM188, BEAM189, SHELL208, SHELL209, REINF264,

 

 

SHELL281, and SOLID285.

 

 

 

User plasticity law

Allows you to calculate plastic strains and form the tangent stress-strain matrix

 

 

at an integration point based on your own plasticity law.

 

User creep equation

Allows you to specify your own creep equation.

 

User swelling law

If you need to account for swelling in an analysis (due to neutron bombard-

 

 

ment, for example), you must write the appropriate swelling law as a user

 

 

routine. No built-in swelling laws are available.

 

User failure criteria

Available for the layered elements (such as SOLID185 Layered Structural Solid,

 

 

SOLID186 Layered Structural Solid, and SHELL281). Up to nine user-defined

 

 

failure criteria can be supplied.

 

 

 

User loads

Body loads such as temperatures, heat generations, and fluences (such as

 

 

neutron flux), as well as surface loads such as pressures, convections, heat

 

 

fluxes and charge density may be defined by way of user-written logic.

 

ANSYS as a subroutine

You can call the entire ANSYS program as a subroutine in your own program,

 

 

such as a user-written design optimization algorithm.

User access at the beginning and end of each ANSYS run solution, load step, substep, and equilibrium iteration

USRSURF116

Allows you to evaluate results and perform any desired calculations during solution.

Allows you to modify SURF151 and SURF152 film coefficients and bulk temperatures based on information from FLUID116.

14.2. Nonstandard Uses of the ANSYS Program

The ANSYS program endures a rigorous verification testing plan before its release. You can be reasonably assured of obtaining good results when you exercise documented features using standard, recommended procedures. In some situations, however, you may need to employ nonstandard procedures or techniques that have not been or cannot be fully tested by ANSYS, Inc. because of their very nature. (An example

is employing user-programmable features.) Be aware that verifying the results in such cases is your responsibility.

14.2.1. What Are Nonstandard Uses?

The results of nonstandard uses of the ANSYS program cannot be predicted; therefore, ANSYS, Inc.'s testing cannot fully cover such uses. Although ANSYS, Inc. does not discourage nonstandard uses, you must exercise caution and use your engineering judgment when doing so. For example, if you program

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of ANSYS, Inc. and its subsidiaries and affiliates.

339

vk.com/club152685050User-Programmable Features| vkand.com/id446425943N nstandard Uses

your own element and use it in an ANSYS analysis, the results depend primarily on how well you programmed the element. In such cases, you must verify the results and make sure that other, standard areas of the program are not adversely affected.

Following is a partial list of nonstandard ANSYS features and uses:

User programmable features (UPFs) - writing your own user routines, linking them into the ANSYS executable, and using them in an analysis. UPFs are described earlier in this chapter.

Reading into the ANSYS program an ANSYS file which was created or modified external to the ANSYS program, for example, a results file or a superelement file created by you or by another program.

High-risk capabilities such as the following:

Changing element real constants during the solution phase in between load steps. Depending on the element type being used, the element may not properly use the updated real constant value.

Deactivating the cross-reference checking of the solid model (via the MODMSH,NOCHECK command).

Turning off element shape-checking (via the SHPP,OFF command).

Using undocumented features, such as an element option not documented in the Element Reference or a command argument not mentioned in the Command Reference. Undocumented features are, by definition, unsupported and unverified; use them with caution.

If the ANSYS program can detect the use of a nonstandard feature, it will often issue a warning message to that effect.

14.2.2. Hints for Nonstandard Use of ANSYS

Follow these guidelines when you need to use the ANSYS program in a nonstandard manner:

Use your engineering judgment and carefully review the analysis results.

Do not assume that other, standard areas of the program are not affected. Run a few test problems to verify.

If you need to contact ANSYS, Inc. Technical Support concerning an analysis involving nonstandard use of the ANSYS program, be sure to mention the nature and extent of the nonstandard feature that you employed.

For detailed information on UPFs, see the Guide to User-Programmable Features.

 

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340

of ANSYS, Inc. and its subsidiaries and affiliates.