ic

Mapdl.ic(node='', lab='', value='', value2='', nend='', ninc='', **kwargs)

Specifies initial conditions at nodes.

APDL Command: IC

Parameters
  • node – Node at which initial condition is to be specified. If ALL, apply to all selected nodes (NSEL). If NODE = P, graphical picking is enabled and all remaining command fields are ignored (valid only in the GUI). A component name may be substituted for NODE.

  • lab – Degree-of-freedom label for which the initial condition is to be specified. If ALL, use all appropriate labels.

  • value – Initial value of the degree of freedom (first-order value). Defaults to the program default for that degree of freedom (0.0 for structural analysis, TUNIF for thermal analysis, etc.). Values are in the nodal coordinate system and in radians for rotational degrees of freedom.

  • value2 – Second-order degree of freedom value, mainly used to specify initial structural velocity. Defaults to the program default for that degree of freedom (0.0 for structural analysis). Values are in the nodal coordinate system and in radians/time for rotational degrees of freedom.

  • nend – Specifies the same initial condition values at the range of nodes from NODE to NEND (defaults to NODE), in steps of NINC (defaults to 1).

  • ninc – Specifies the same initial condition values at the range of nodes from NODE to NEND (defaults to NODE), in steps of NINC (defaults to 1).

Notes

The IC command specifies initial conditions, which are the initial values of the specified degrees of freedom. It is valid only for a static analysis and full method transient analysis (TIMINT,ON and TRNOPT,FULL). For the transient, the initial value is specified at the beginning of the first load step, that is, at time = 0.0.

Initial conditions should always be step applied (KBC,1) and not ramped.

If constraints (D, DSYM, etc.) and initial conditions are applied at the same node, the constraint specification overrides. Exercise caution when specifying constraints. The degree-of-freedom values start from zero, or the first value given in the table when table name is specified. To match the nonzero initial condition value with the initial value for degree-of-freedom constraint, use a table for the degree-of-freedom constraint.

For thermal analyses, any TUNIF specification should be applied before the IC command; otherwise, the TUNIF specification is ignored. If the IC command is input before any TUNIF specification, use the ICDELE command and then reissue any TUNIF specification and then follow with the IC command.

When issuing the IC command for elements SOLID278 Layered Thermal Solid and SOLID279 Layered Thermal Solid with through-the-thickness degrees of freedom (KEYOPT(3) = 2), layers are always interpolated linearly based on the location of the degrees of freedom.

Define consistent initial conditions. For example, if you define an initial velocity at a single degree of freedom, the initial velocity at every other degree of freedom will be 0.0, potentially leading to conflicting initial conditions. In most cases, you should define initial conditions at every unconstrained degree of freedom in your model. If you define an initial condition for any degree of freedom at the pilot node of a rigid body (see Modeling Rigid Bodies in the Contact Technology Guide for the definition of rigid body), then the same initial condition must also be defined for the same degree of freedom on all other nodes of the rigid body.

After a solution has been performed, the specified initial conditions are overwritten by the actual solution and are no longer available. You must respecify them if you want to perform a subsequent analysis. You may want to keep a database file saved prior to the first solution for subsequent reuse.

If you use the CDWRITE command to archive your model, first-order values (initial displacements, temperatures, etc.) specified via the IC command are not written to the archive file; however, second-order (structural velocity) terms are written.

This command is also valid in PREP7.