gcdef#

Elements.gcdef(option='', sect1='', sect2='', matid='', realid='', sect1end='', sect2end='', **kwargs)#

Defines interface interactions between general contact surfaces.

Mechanical APDL Command: GCDEF

Parameters:
optionstr

Option to be performed.

  • (blank) - Retain the previous Option setting between SECT1 and SECT2.

  • AUTO - Define auto asymmetric contact between surfaces SECT1 and SECT2.

  • SYMM - Define symmetric contact between surfaces SECT1 and SECT2.

  • ASYM - Define asymmetric contact with SECT1 as the source (contact) surface and SECT2 as the target surface.

  • EXCL - Exclude contact between surfaces SECT1 and SECT2. MATID, REALID, SECT1END, and SECT2END are ignored.

  • DELETE - Remove the given definition from the gcdef table. MATID, REALID, SECT1END, and SECT2END are ignored.

    Note that gcdef,DELETE,ALL,ALL does not remove the entire gcdef table; it merely removes any existing gcdef,,ALL,ALL definitions, while leaving intact any existing gcdef definitions that are more specific.

    To remove the entire gcdef table, issue gcdef,DELETE,TOTAL.

    It is good practice to list all definitions using gcdef,LIST before and after a gcdef,DELETE command.

  • LIST - List stored gcdef data entries. MATID and REALID are ignored.

    gcdef,LIST lists all defined interactions. gcdef,LIST, SECT1, SECT2 lists the entry for the specific SECT1 / SECT2 interaction. gcdef,LIST,ALL,ALL lists only the ALL,ALL entry (if any).

  • TABLE - List interpreted general contact definitions in tabular format. MATID and REALID are ignored.

    By default, rows/columns of the table that match neighboring rows/columns are compressed to simplify the table. Issue gcdef,TABLE,TOTAL to list the entire gcdef table without removal of duplicate rows and columns.

  • TABLESOL - List a table showing actual interactions considered during solution. This option is only available after the solve command. MATID and REALID are ignored.

    The table shows MAT and REAL entries considered during the solution (actual contact may or may not have occurred). This is in contrast to gcdef,TABLE, which shows the user specifications. For auto asymmetric contact, TABLESOL indicates which of the possible contact versus target surface combinations was considered.

sect1str

Section numbers representing contact ( SECT1 ) and target ( SECT2 ) general contact surfaces (no defaults). (In most cases, the actual determination of contact versus target surfaces takes place during solve.)

A node component name is also valid input for SECT1 and SECT2. The component name is not stored. Instead, the program loops through all valid section IDs found in the component and creates gcdef entries for all possible SECT1/SECT2 combinations that result. These entries are reflected in the Option = LIST and TABLE output. Section IDs can be further controlled by adding an extension (_EDGE, _FACE, _VERT, _TOP, or _BOT) to the end of the component name. See in the Contact Technology Guide for more information.

The following labels are also valid input:

  • SELF - Self contact.

  • ALL - All general contact sections IDs.

  • ALL_EDGE - Section IDs of all CONTA177 general contact line elements (which may be on the edges of 3D solid and shell base elements, or on beam base elements).

  • ALL_FACE - Section IDs of all general contact elements on faces of solid or shell base elements (both top and bottom faces of shell elements).

  • ALL_VERT - Section IDs of all CONTA175 general contact vertex elements (which may be on convex corners of solid and shell base elements, and on endpoints of beam base elements).

  • ALL_TOP - Section IDs of all general contact elements on top faces of shell base elements, and faces of solid base elements.

  • ALL_BOT - Section IDs of general contact elements on bottom faces of shell base elements, and faces of solid base elements.

The ALL labels apply to all defined general contact element section IDs in the model without regard to the select status of the elements or attached nodes.

See SECT1/ SECT2 Interactions SECT1 / SECT2 Interactions for a description of how the various inputs for SECT1 and SECT2 are interpreted.

sect2str

Section numbers representing contact ( SECT1 ) and target ( SECT2 ) general contact surfaces (no defaults). (In most cases, the actual determination of contact versus target surfaces takes place during solve.)

A node component name is also valid input for SECT1 and SECT2. The component name is not stored. Instead, the program loops through all valid section IDs found in the component and creates gcdef entries for all possible SECT1/SECT2 combinations that result. These entries are reflected in the Option = LIST and TABLE output. Section IDs can be further controlled by adding an extension (_EDGE, _FACE, _VERT, _TOP, or _BOT) to the end of the component name. See in the Contact Technology Guide for more information.

The following labels are also valid input:

  • SELF - Self contact.

  • ALL - All general contact sections IDs.

  • ALL_EDGE - Section IDs of all CONTA177 general contact line elements (which may be on the edges of 3D solid and shell base elements, or on beam base elements).

  • ALL_FACE - Section IDs of all general contact elements on faces of solid or shell base elements (both top and bottom faces of shell elements).

  • ALL_VERT - Section IDs of all CONTA175 general contact vertex elements (which may be on convex corners of solid and shell base elements, and on endpoints of beam base elements).

  • ALL_TOP - Section IDs of all general contact elements on top faces of shell base elements, and faces of solid base elements.

  • ALL_BOT - Section IDs of general contact elements on bottom faces of shell base elements, and faces of solid base elements.

The ALL labels apply to all defined general contact element section IDs in the model without regard to the select status of the elements or attached nodes.

See SECT1/ SECT2 Interactions SECT1 / SECT2 Interactions for a description of how the various inputs for SECT1 and SECT2 are interpreted.

matidstr

Material ID number for general contact interaction properties at the SECT1 / SECT2 interface. If zero or blank, the previous setting of MATID for SECT1 / SECT2 (if any) is retained.

As an example, you could specify “always bonded” contact behavior at the interface by setting MATID to 2 and issuing the command tb,INTER,2,,,ABOND.

The coefficient of friction MU is also defined by MATID. Since the default is MATID = 0, frictionless contact (MU = 0) is assumed by default.

realidstr

Real constant ID number for general contact interaction properties at the SECT1 / SECT2 interface. If zero or blank, the previous setting of REALID for SECT1 / SECT2 (if any) is retained.

As an example, you could specify contact stiffness (FKN) = 10 at the interface by setting REALID to 14 and issuing the command r,14,,,10.

sect1endstr

Last section number in the range. For Option = LIST, TABLE, or TABLESOL, data entries are processed for contact section numbers in the range from SECT1 to SECT1END, and target section numbers in the range from SECT2 to SECT2END. SECT1END and SECT2END are ignored for all other Option labels.

sect2endstr

Last section number in the range. For Option = LIST, TABLE, or TABLESOL, data entries are processed for contact section numbers in the range from SECT1 to SECT1END, and target section numbers in the range from SECT2 to SECT2END. SECT1END and SECT2END are ignored for all other Option labels.

Notes

gcdef defines the interface interaction between general contact surfaces identified by SECT1 and SECT2. gcdef commands are order independent in most cases.

gcdef definitions should be issued after gcgen. They are saved in the database and are written to and read from .CDB files.

See General Contact

SECT1/ SECT2 Interactions

The most specific types of general contact definitions are those described below:

  • SECT1 = any valid general surface section ID and SECT2 = any different valid general surface section ID: Option, MATID, and REALID apply to general surface interactions between SECT1 and SECT2. This is one of the most specific types of general contact definitions and is never overridden.

  • SECT1 = any valid general surface section ID and SECT2 = SECT1 : Option, MATID, and REALID apply to general surface self contact interactions involving SECT1. This is one of the most specific types of general contact definitions and is never overridden.

The remaining general contact definition types can be overridden by the above two general contact definition types:

  • SECT1 = ALL and SECT2 = ALL: Option, MATID, and REALID apply to all general surface interactions, except where overridden by a more specific gcdef command.

  • SECT1 = ALL and SECT2 = SELF or SECT1 = SELF and SECT2 = ALL: Option, MATID, and REALID apply to all general surface self contact interactions, except where overridden by a more specific gcdef command.

  • SECT1 = ALL and SECT2 = any valid general surface section ID: Option, MATID, and REALID apply to all general surface interactions that include SECT2, except where overridden by a more specific gcdef command.

  • SECT1 = any valid general surface section ID and SECT2 = ALL: Option, MATID, and REALID apply to all general surface interactions that include SECT1, except where overridden by a more specific gcdef command.