f

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

Specifies force loads at nodes.

APDL Command: F

Parameters
  • node – Node at which force is to be specified. If ALL, NEND and NINC are ignored and forces are applied 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 also be substituted for NODE.

  • lab – Valid force label. Structural labels: FX, FY, or FZ (forces); MX, MY, or MZ (moments). Thermal labels: HEAT, HBOT, HE2, HE3, …, HTOP (heat flow). Fluid labels: FLOW (fluid flow). Electric labels: AMPS (current flow), CHRG (electric charge). Magnetic labels: FLUX (magnetic flux); CSGX, CSGY, or CSGZ (magnetic current segments). Diffusion labels: RATE (diffusion flow rate).

  • value – Force value or table name reference for specifying tabular boundary conditions. To specify a table, enclose the table name in percent signs (%), e.g., F, NODE,HEAT,%tabname%). Use the *DIM command to define a table.

  • value2 – Second force value (if any). If the analysis type and the force allow a complex input, VALUE (above) is the real component and VALUE2 is the imaginary component.

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

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

Notes

The available force loads per node correspond to the degrees of freedom listed under “Degrees of Freedom” in the input table for each element type in the Element Reference. If both a force and a constrained degree of freedom [D] are specified at the same node, the constraint takes precedence. Forces are defined in the nodal coordinate system. The positive directions of structural forces and moments are along and about the positive nodal axis directions. The node and the degree of freedom label corresponding to the force must be selected [NSEL, DOFSEL].

For hydrostatic fluid elements (HSFLD241 and HSFLD242), DVOL is used to specify fluid mass flow rate (with units of mass/time) at the pressure node. This allows fluid to be added or taken out of the fluid elements sharing the pressure node. A fluid density must also be specified (via the MP command or TB command) to apply a volume change corresponding to the prescribed fluid mass flow rate.

Tabular boundary conditions (VALUE = %tabname%) are available only for the following labels: Fluid (FLOW), Electric (AMPS), Structural force (FX, FY, FZ, MX, MY, MZ), and Thermal (HEAT, HBOT, HE2, HE3, …, HTOP). Tabular boundary conditions are valid only in static (ANTYPE,STATIC), full transient (ANTYPE,TRANS), full harmonic (ANTYPE, HARMIC), modal superposition harmonic and modal superposition transient analyses.

This command is also valid in PREP7.