BFE
BFE, Elem, Lab, STLOC, VAL1, VAL2, VAL3, VAL4
Defines an element body-force load.
ElemThe element to which body load applies. If ALL, apply to all selected elements (ESEL). A component name may also be substituted for
Elem.LabValid body load label. Valid labels are also listed for each element type in the Element Reference under "Body Loads" in the input table.
Discipline Body Load Label Label Description Structural TEMP Temperature FREQ Frequency (harmonic analyses only) FLUE Fluence FORC Body-force density Thermal HGEN Heat generation rate (updated by volume changes when large-deflection effects are included (NLGEOM,ON)) Magnetic EF Electric field TEMP Temperature JS Current density MVDI Magnetic virtual displacements flag Electric TEMP Temperature CHRGD Charge density Field volume interface FVIN Field volume interface flag Poromechanics FSOU Fluid flow source Diffusion TEMP Temperature DGEN Diffusing substance generation rate STLOCStarting location for entering
VALdata, below. For example, ifSTLOC= 1, data input in theVAL1field applies to the first element body load item available for the element type,VAL2applies to the second element item, etc. IfSTLOC= 5, data input in theVAL1field applies to the fifth element item, etc. Defaults to 1.VAL1,VAL2,VAL3,VAL4For
Lab= TEMP, FLUE, DGEN, HGEN, and CHRGD,VAL1--VAL4represent body load values at the starting location and subsequent locations (usually nodes) in the element.VAL1can also represent a table name for use with tabular boundary conditions. Enter onlyVAL1for a uniform body load across the element. For nonuniform loads, the values must be input in the same order as shown in the input table for the element type. Values initially default to the BFUNIF value (except for CHRGD which defaults to zero). For subsequent specifications, a blank leaves a previously specified value unchanged; if the value was not previously specified, the default value as described in the Element Reference is used.For
Lab= JS andSTLOC= 1,VAL1,VAL2andVAL3are the X, Y, and Z components of current density (in the element coordinate system), andVAL4is the phase angle.For
Lab= EF andSTLOC= 1,VAL1,VAL2, andVAL3are the X, Y, and Z components of electric field (in the global Cartesian coordinate system).If
Lab= FVIN in a unidirectional Mechanical APDL to Ansys CFX analysis,VAL2is the volume interface number (not available from within the GUI), andVAL1,VAL3, andVAL4are not used.For
Lab= FORC andSTLOC= 1,VAL1,VAL2, andVAL3are the real X, Y, and Z components of force density (in the global Cartesian coordinate system).For analyses that allow complex input, if
Lab= FORC andSTLOC= 4,VAL1,VAL2, andVAL3are the imaginary X, Y, and Z components of force density (in the global Cartesian coordinate system).
Notes
Defines an element body-force load (such as the temperature in a structural analysis or the heat-generation rate in a thermal analysis). Body loads and element specific defaults are described for each element type in the Element Reference. If both the BF and BFE commands are used to apply a body-force load to an element, the BFE command takes precedence.
Body-Force Density (FORC)
Imaginary values for FORC loading via BFE is supported by current-technology solid elements (PLANE182, PLANE183, SOLID185, SOLID186, SOLID187, and SOLID285) and reinforcing elements (REINF263, REINF264, and REINF265). Use only for modal or harmonic analyses. Large-deflection effects must be disabled (NLGEOM,OFF).
Heat-Generation Loading (HGEN)
The following topics for applying HGEN loading via the BFE command are available:
On Layered Thermal Solid Elements
For HGEN loading on layered thermal solid elements SOLID278 /
SOLID279 (KEYOPT(3) = 1 or 2), or layered thermal shell
elements SHELL131 / SHELL132 (KEYOPT(3)
= 1), and SHELL294, STLOC
refers to the layer number (not the node). In such
cases, specify VAL1 through VAL4 to
specify the heat-generation values for the appropriate layers. Heat generation is constant
over the layer.
On Reinforcing Elements
For HGEN loading on reinforcing elements REINF263,
REINF264, and REINF265,
STLOC refers to the corner locations of the reinforcing
members (individual reinforcings):
For FORC loading on reinforcing elements,
STLOC refers to real (STLOC = 1)
or imaginary (STLOC = 4) components.
When using the standard
method for defining reinforcing, this is the only way to apply a body load (HGEN
or FORC) on the reinforcing members created after generating the
REINFnnn reinforcing elements (EREINF). If
applying FORC loading, Mechanical APDL applies a uniform load to all reinforcing members if there
are multiple members in selected elements.
When using the mesh-independent method for defining reinforcing, you can apply a body load on
the reinforcing members in the same way. The preferred method,
however, is to apply loads on the MESH200 elements (via
BFE or BF for HGEN, BFE for FORC)
before generating the REINFnnn
reinforcing elements (EREINF). Mechanical APDL maps the loads from the
MESH200 elements to the newly generated
REINFnnn reinforcing elements automatically. If you need to
apply the loads after generating the reinforcing elements, apply them
to MESH200 elements and issue BFPORT to
transfer the loads to the reinforcing members.
Specifying a Table
You can specify a table name (VAL1) when using temperature
(TEMP), diffusing substance generation rate (DGEN), heat generation rate (HGEN), and current
density (JS) body load labels.
For the body-force-density label (FORC), you can specify a table for any of the
VAL1 through VAL3 arguments. Both
1D and 2D tables are valid; however, only 1D tables are valid in mode-superposition
harmonic and mode-superposition transient analyses.
Enclose the table name (tabname) in percent signs (%), for example:
BFE,
Elem,Lab,STLOC,%tabname%
Use the *DIM command to define a table. For information on primary variables for each load type, see Applying Loads Using Tabular Input in the Basic Analysis Guide.
For Lab = TEMP, each table defines
NTEMP temperatures, as follows:
For layered elements,
NTEMPis the number of layer interface corners that allow temperature input.For non-layered elements,
NTEMPis the number of corner nodes.
The temperatures apply to element items with a starting location of
STLOC + n, where n is the value field
location (VALn) of the table name input.
For layered elements, a single BFE command returns temperatures for one layer interface. Multiple BFE commands are necessary for defining all layered temperatures.
For beam, pipe and elbow elements that allow multiple temperature inputs per node, define the tabular load for the first node only (Node I), as loads on the remaining nodes are applied automatically. For example, to specify a tabular temperature load on a PIPE288 element with the through-wall-gradient option (KEYOPT(1) = 0), the BFE command looks like this:
BFE,
Elem,TEMP,1,%tabOut%, %tabIn%
where %tabOut% and %tabIn%
and are the tables applied to the outer and inner surfaces of the pipe wall,
respectively.
When a tabular function load is applied to an element, the load does not vary according to the positioning of the element in space.
In a mode-superposition harmonic or transient analysis, you must apply the load in the modal portion of the analysis. Mechanical APDL calculates a load vector and writes it to the MODE file, which you can apply via the LVSCALE command.