Mechanical APDL Basic Analysis Guide - Ansys

Mechanical APDL Basic Analysis Guide - Ansys Mechanical APDL Basic Analysis Guide - Ansys

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Chapter 7:The General Postprocessor (POST1) For more information, see the Command Reference for descriptions of the INRES, NSEL, APPEND, PRNSOL, and SUBSET commands. If you wish to clear the database of any previous data, use one of the following methods: Command(s): LCZERO GUI: Main Menu> General Postproc> Load Case> Zero Load Case Either method sets all current values in the database to zero, therefore giving you a fresh start for further data storage. If you set the database to zero before appending data to it, the result is the same as using the SUBSET command or the equivalent GUI path, assuming that the arguments on SUBSET and APPEND are equivalent. Note All of the options available for the SET command are also available for the SUBSET and APPEND commands. By default, the SET, SUBSET, and APPEND commands look for one of these results files: Jobname.RST, Jobname.RTH, Jobname.RMG, or Jobname.RFL. You can specify a different file name by issuing the FILE command (Main Menu> General Postproc> Data & File Opts) before issuing SET, SUBSET, or APPEND. 7.1.3. Creating an Element Table In the ANSYS program, the element table serves two functions. First, it is a tool for performing arithmetic operations among results data. Second, it allows access to certain element results data that are not otherwise directly accessible, such as derived data for structural line elements. (Although the SET, SUBSET, and APPEND commands read all requested results items into the database, not all data are directly accessible with commands such as PLNSOL, PLESOL, etc.). Think of the element table as a spreadsheet, where each row represents an element, and each column represents a particular data item for the elements. For example, one column might contain the average SX stress for the elements, while another might contain the element volumes, while yet a third might contain the Y coordinate of the centroid for each element. To create or erase the element table, use one of the following: Command(s): ETABLE GUI: Main Menu> General Postproc> Element Table> Define Table Main Menu> General Postproc> Element Table> Erase Table 7.1.3.1. Filling the Element Table for Variables Identified By Name To identify an element table column, you assign a label to it using the Lab field (GUI) or the Lab argument on the ETABLE command. This label will be used as the identifier for all subsequent POST1 commands involving this variable. The data to go into the columns is identified by an Item name and a Comp (component) name, the other two arguments on the ETABLE command. For example, for the SX stresses mentioned above, SX could be the Lab, S would be the Item, and X would be the Comp argument. Some items, such as the element volumes, do not require Comp; in such cases, Item is VOLU and Comp is left blank. Identifying data items by an Item, and Comp if necessary, is called the "Component Name" method of filling the element table. The data which are accessible with the component name method are data generally calculated for most element types or groups of element types. 134 Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates.

The ETABLE command documentation lists, in general, all the Item and Comp combinations. See the "Element Output Definitions" table in each element description in the Element Reference to see which combinations are valid. Table 1: "BEAM188 Element Output Definitions" is an example of such a table for BEAM188. You can use any name in the Name column of the table that contains a colon (:) to fill the element table via the Component Name method. The portion of the name before the colon should be input for the Item argument of the ETABLE command. The portion (if any) after the colon should be input for the Comp argument. The O and R columns indicate the availability of the items in the file Jobname.OUT (O) or in the results file (R): a Y indicates that the item is always available, a number refers to a table footnote which describes when the item is conditionally available, and a - indicates that the item is not available. 7.1.3.2. Filling the Element Table for Variables Identified By Sequence Number You can load data that is not averaged, or that is not naturally single-valued for each element, into the element table. This type of data includes integration point data, all derived data for structural line elements (such as spars, beams, and pipes) and contact elements, all derived data for thermal line elements, layer data for layered elements, etc. These data are listed in the "Item and Sequence Numbers for the ETABLE and ESOL Commands" table with each element type description in the Command Reference. Table 2: "BEAM188 Item and Sequence Numbers" is an example of such a table for BEAM188. The data in the tables is broken down into item groups, such as LS, LEPEL, SMISC, etc. Each item within the item group has an identifying "sequence" number listed. You load these data into the element table by giving the item group as the Item argument on the ETABLE command, and the sequence number as the Comp argument. This is referred to as the "Sequence Number" method of filling the element table. For some line elements, KEYOPT settings govern the amount of data calculated. This can change the sequence number of a particular data item. Therefore, in these cases a table for each KEYOPT setting is provided. 7.1.3.3. Considerations for Defining Element Tables • The ETABLE command works only on the selected elements. That is, only data for the elements you have selected are moved to the element table. By changing the selected elements between ETABLE commands, you can selectively fill rows of the element table. • The same Sequence Number combination may mean different data for different element types. For example, the combination SMISC,1 means P1 for SOLID185 (pressure on face 1), and MECHPOWER for TRANS126 (mechanical power). Therefore, if your model has a combination of element types, be sure to select elements of one type (using ESEL or Utility Menu> Select> Entities) before using the ETABLE command. • The element table is not automatically refilled (updated) when you read in a different set of results (such as for a different load step) or when you alter the results in the database (such as by a load case combination). For example, suppose your model consists of our sample elements, and you issue the following commands in POST1: SET,1 ! Read in results for load step 1 ETABLE,ABC,lS,6 ! Move SDIR at end J (KEYOPT(9)=0) to the element table ! under heading "ABC" SET,2 ! Read in results for load step 2 At this point, the "ABC" column in the element table still contains data for load step 1. To refill (update) the column with load step 2 values, you should issue the command ETABLE,REFL, or specify the refill option via the GUI. Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. 7.1.3. Creating an Element Table 135

The ETABLE command documentation lists, in general, all the Item and Comp combinations. See the "Element<br />

Output Definitions" table in each element description in the Element Reference to see which combinations<br />

are valid.<br />

Table 1: "BEAM188 Element Output Definitions" is an example of such a table for BEAM188. You can use any<br />

name in the Name column of the table that contains a colon (:) to fill the element table via the Component<br />

Name method. The portion of the name before the colon should be input for the Item argument of the<br />

ETABLE command. The portion (if any) after the colon should be input for the Comp argument. The O and<br />

R columns indicate the availability of the items in the file Jobname.OUT (O) or in the results file (R): a Y<br />

indicates that the item is always available, a number refers to a table footnote which describes when the<br />

item is conditionally available, and a - indicates that the item is not available.<br />

7.1.3.2. Filling the Element Table for Variables Identified By Sequence Number<br />

You can load data that is not averaged, or that is not naturally single-valued for each element, into the element<br />

table. This type of data includes integration point data, all derived data for structural line elements (such as<br />

spars, beams, and pipes) and contact elements, all derived data for thermal line elements, layer data for<br />

layered elements, etc. These data are listed in the "Item and Sequence Numbers for the ETABLE and ESOL<br />

Commands" table with each element type description in the Command Reference. Table 2: "BEAM188 Item<br />

and Sequence Numbers" is an example of such a table for BEAM188.<br />

The data in the tables is broken down into item groups, such as LS, LEPEL, SMISC, etc. Each item within the<br />

item group has an identifying "sequence" number listed. You load these data into the element table by<br />

giving the item group as the Item argument on the ETABLE command, and the sequence number as the<br />

Comp argument. This is referred to as the "Sequence Number" method of filling the element table.<br />

For some line elements, KEYOPT settings govern the amount of data calculated. This can change the sequence<br />

number of a particular data item. Therefore, in these cases a table for each KEYOPT setting is provided.<br />

7.1.3.3. Considerations for Defining Element Tables<br />

• The ETABLE command works only on the selected elements. That is, only data for the elements you<br />

have selected are moved to the element table. By changing the selected elements between ETABLE<br />

commands, you can selectively fill rows of the element table.<br />

• The same Sequence Number combination may mean different data for different element types. For<br />

example, the combination SMISC,1 means P1 for SOLID185 (pressure on face 1), and MECHPOWER for<br />

TRANS126 (mechanical power). Therefore, if your model has a combination of element types, be sure to<br />

select elements of one type (using ESEL or Utility Menu> Select> Entities) before using the ETABLE<br />

command.<br />

• The element table is not automatically refilled (updated) when you read in a different set of results (such<br />

as for a different load step) or when you alter the results in the database (such as by a load case combination).<br />

For example, suppose your model consists of our sample elements, and you issue the following<br />

commands in POST1:<br />

SET,1 ! Read in results for load step 1<br />

ETABLE,ABC,lS,6 ! Move SDIR at end J (KEYOPT(9)=0) to the element table<br />

! under heading "ABC"<br />

SET,2 ! Read in results for load step 2<br />

At this point, the "ABC" column in the element table still contains data for load step 1. To refill (update) the<br />

column with load step 2 values, you should issue the command ETABLE,REFL, or specify the refill option<br />

via the GUI.<br />

Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information<br />

of ANSYS, Inc. and its subsidiaries and affiliates.<br />

7.1.3. Creating an Element Table<br />

135

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