Group/Element Selection Commands

2.6. Group/Element Selection Commands

2.6.1. GROU Command

Specifies the ASAS group numbers to be processed by subsequent execution commands (AVST, PRST, SHRS, WOOD and REIN)

Parameters

GROU : keyword

igroup : ASAS group number to be processed (Integer). All the group numbers specified must exist otherwise POST will stop after data checking.

GROU

igroup END

ALL

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END : keyword to denote the end of the current block of group number data. If the list of group numbers continues onto subsequent lines, END is required on last line only.

ALL : keyword to indicate that all groups are selected. END is not required.

Note

If this command is omitted, and provided no extra groups are specified (see Section 2.6.2, EXTR groups) then all the ASAS groups will be processed by default. If this command is omitted, but extra groups are defined, then none of the ASAS groups will be processed.

Examples

(i) To process ASAS groups 1 2 3 4

GROU

1 -4 END

(ii) To process all ASAS groups

GROU ALL

(iii) To process ASAS groups 1,3,5,7,10,12,14 GROU

1 3 5 7 10 12 14 END

2.6.2. EXTR Command

Defines new group numbers and assigns elements to the groups for processing by subsequent execution commands (AVST, PRST, SHRS, WOOD and REIN)

Parameters EXTR

igroup ielem END

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EXTR : keyword

igroup : group number for new group to be generated (Integer). This group number must be unique and must not exist in the original ASAS analysis.

ielem : user element numbers to be included in the new group (Integer).

END : keyword to denote the end of the current block of extra group data. If the list of element numbers continues onto subsequent lines, END is required on last line only.

Note

1. One extra group is defined by each EXTR group command. Up to 50 groups may be processed at a time.

2. This command effectively removes the elements from their original ASAS group since an element may only be in one group at a time.

3. EXTR groups may be redefined with different lists of elements in separate runs of POST provided the Interface file is not saved from run to run.

4. Note that if EXTR groups are created in POST, then the CREATE Command should be used on the SAVE FEMS line.

Examples

(i) New group 12 contains elements 7 to 35

EXTR

12 7 -35 END

(ii) New group 5 contains elements 1 to 10 and new group 7 contains elements 11 to 20

EXTR

5 1 -10 END EXTR

7 11 12 13 14 15 -20 END

2.6.3. SKIP Command

Specifies user element numbers which are to be excluded from the analysis.

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Parameters

SKIP : keyword

ielem : user element number to be skipped (Integer)

END : keyword to denote the end of the SKIP data. If the list of element numbers continues onto subsequent lines, END is required on last line only.

Note

1. This command is used to remove elements from an ASAS group. If the skipped elements need processing on their own, the EXTR group command should be used which will remove the elements in the extra group from their original ASAS groups.

2. Up to 500 elements may be skipped.

Example

SKIP

1 7 9 END

2.6.4. NOAV Command

Specifies that no averaging of adjacent element stresses is to be carried out.

Parameters SKIP

END ielem

NOAV

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NOAV : keyword Notes

1. By default, nodal stresses of adjacent elements within a group are averaged and reported. For model checking it may be useful to manually check the absolute variation from element to element in a consistent axis set using this command together with an output axis system definition. (OUTP, OUTR, OUTT).

2. With the NOAV command no thickness checks are carried out to ensure that all elements at a node have the same thickness.

3. This command will require a significantly larger data area (see Appendix A.2) and will produce larger results files than usual and thus should be used with care.

2.6.5. AVGR Command

Specifies a set of group numbers which are to be considered as one single group for the purposes of stress averaging.

Parameters

AVGR : keyword

igroup : group number (Integer). This may be either an ASAS group or one defined in an earlier EXTR group command.

END : keyword to denote the end of the current block of averaged group data. If the list of group numbers continues onto subsequent lines, END is required on last line only.

ALL : keyword to indicate that all groups are selected. END is not required.

Notes

1. By default, stress averaging only occurs between elements which are in the same group. (See Section 1.4). There may be situations, however, where groups of elements require different axis sets but stress averaging across the group boundaries is both desirable and meaningful (see Figure 10). This may be

AVGR

igroup END

ALL

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achieved by use of the output axis commands (CONS, OUTP, OUTR, OUTT) and AVGR (See Section 1.6.4).

2. The results will be reported under the first group number appearing in the list.

Example (see Figure 10) OUTP

0.0 0.0 1.0 0.0 0.0 50.0 GROUP

1 END OUTT

50.0 0.0 100.0 0.0 1.0 0.0 50.0 GROUP

2 END OUTP

1.0 0.0 0.0 100.0 0.0 150.0 GROUP

3 END OUTR

200.0 0.0 150.0 150.0 0.0 200.0 GROUP

4 END AVGR

1 2 3 4 END