Element TablesUse of Element Tables in ANSYS

Sheldon ImaokaCollaborative Solutions, Inc.

09/14/00

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Definition of Element Tables

• An Element Table (ETABLE) is a “spreadsheet” ofelement information within ANSYS. These static arraysof information can be listed, printed, or operated uponfor the following purposes:– ETABLE can be used to manipulate results for postprocessing,

such as plotting “factors of safety” instead of stress values

– Some elements have information which is pertinent only tothat element. Hence, ETABLE is needed to retrieve thesevalues. An example is obtaining moment and shear diagramsfor BEAM elements.

– Element tables are static tables, so they can be used tocompare different results with each other (basic element tablevalues can be updated automatically)

Usage of ETABLE

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How to Access ETABLE

• ETABLE commands are accessible in the followinglocations:

“Main Menu > General Postproc > Element Table”

“Main Menu > General Postproc > Plot Results”

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Steps Involved in Creating ETABLEs

1) Solve problem and load results set (as needed)

2) Define element table(s)– “Main Menu > General Postproc > Element Table > Define

Table”

3) Perform operations on tables as required– “Main Menu > General Postproc > Element Table” allows

summing, adding, multiplying, taking vector or cross productof tables, just to name a few examples.

4) Plot or list element tables– Plotting includes contour plots, line element results plots, or

vector plots in “Main Menu > General Postproc > Plot Results”

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Steps to Create ETABLE

1) Solve problem and load results set (as needed)– Define results coordinate system, layer for SHELL elements

General Postproc > Results Summary…

General Postproc > Options for Outp…

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Steps to Create ETABLE (cont.)

2) Define element table(s)– “Main Menu > General Postproc > Element Table > Define

Table” Provide User-Defined Name

Select Category

Select Item

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Steps to Create ETABLE (cont.)

3) Perform operations on tables as required– Sum, add, multiply, take vector or cross product of tables.

General Postproc > Element TableExample of Adding two element tables

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Steps to Create ETABLE (cont.)

4) Plot or list element tables– Plotting can be performed with or without averaging

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Obtaining Element-Specific Data

• Look up elementinformation in onlinehelp.

• There will be a sectionfor each elemententitled “Output Data”

• A list of element-specific data (“Name”)will be shown with“Item” such as “SMISC”or “NMISC”

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Obtaining Element-Specific Data (cont.)

• For this example, a user wants N12, defined as “in-plane elementstress resultant” for SHELL181 in the online help. Use theinformation in the table “SMISC, 3” from the chart in the previouspage to obtain “N12”.

Examples of ETABLE

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BEAM189 Example

• BEAM elements can be plotted with bending moment or shearforce diagrams. Bending for Node I and J are noted below asSMISC,2 and SMISC,15, respectively

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BEAM189 Example

• After defining element tables for MY for node I and J, these areplotted as “Line Element Results” as noted below:

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BEAM189 Example

Resulting lineplot is shownat top-right.Allows forvisualizingmomentvariation fromnodes I to J foreach element.

Force is 100,length is 100,so we expectmax momentof 10000, asnoted on right.

Line Element Result Plot with ETABLEs

Contour plot of displacement with /ESHAPE,1

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SHELL181 Example

• Stress resultants(force/length)can be obtainedfor SHELL181.Nij, Mij, and Qijare available asnoted in theonline help

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SHELL181 Example

• In the online help,the “SequenceNumbers” for Nij,Mij, and Qij arelisted for ETABLEdefinition purposes.

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SHELL181 Example

Resulting plot ofSX and M11 fora pressure-loaded plate isshown on right.

SX=6*M11/t2

For this case,max SX is990638.Thickness is 0.1,so we expectM11 to be1651.06, whichthe obtainedresult.

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SOLID92 Example

For a given mesh,we may want tocalculatevolumetricproperties. Thismay also include2D planar oraxisymmetricelements.Element tablesallow us to obtainvolume of eachelement whichwe can then sum(SSUM command)

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SOLID92 Example

• Compare solid model volume (VSUM) with volume obtained bysumming each element’s volume (SSUM)

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SURF152 Example

Element tablesof thermal solidsor thermalsurface effectelements can beused to obtainheat losses dueto convection(and radiation).In this example,we will look atlosses due toboth modes ofheat transfer forSURF154

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SURF152 Example

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SURF152 Example

• Total heat flow rate is 14.2216, which can be confirmed withreaction force (heat flow).

• Define element tables for heat flow rate due to convection andradiation.

• Sum the values to obtain totals.

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SURF152 Example

• Results noted below. Heat loss due to convection is 8.25, due toradiation is 5.97. This adds up to 14.22, as expected for heatbalance.

• From the results, one can conclude that radiation is a significantheat path, as posed by the problem description. (One would havedone thermal resistance network to confirm this beforehand)

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Thermal Example

Element tablesare static, soone can getelement tablesfor differentload cases (asshown onright) andcompareresults. Withflux doubled,we expect ∆Tdoubled aswell, which iswhat we get.

Conclusion

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Additional Considerations

• Element tables are generally centroid values of elements. Someelement tables can be a value at a given node, but only one valuewill be stored per element per ETABLE– For ETABLE results of DOF & other nodal quantities, these will be

average of nodes of element, so min/max values will be reportedlower than nodal values

• Parameter arrays can be inserted into ETABLE via *VPUT command– “Utility Menu > Parameters > Array Operations > Put Array Data…”

• Be sure to select the appropriate elements PRIOR to definingelement tables, such that any calculations include only thosepertinent element types– Some sequence items such as SMISC,2 or NMISC,5 mean different

things for different elements. Including all elements may invalidateany further calculations.

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Further References

• Ch. 5.2.3 “Creating an Element Table”, ANSYS 5.6 BasicAnalysis Procedures Guide

• Ch. 2.2.2.2 “The ‘Item and Sequence Number’ Table”,ANSYS 5.6 Elements Reference

• “ETABLE”, ANSYS 5.6 Commands Reference