SFE, Elem, LKEY, Lab, KVAL, VAL1, VAL2, VAL3, VAL4
Specifies surface loads on elements.
ElemElement to which surface load applies. If ALL, apply
load to all selected elements [ESEL]. If Elem = P, graphical picking is enabled and all remaining
command fields are ignored (valid only in the GUI). A component name
may be substituted for Elem.
LKEYLoad key or face number associated with surface load (defaults to 1). Load keys (1,2,3, etc.) are listed under "Surface Loads" in the input data table for each element type in the Element Reference.
LabValid surface load label. Load labels are listed under "Surface Loads" in the input table for each element type in the Element Reference.
| Discipline | Surface Load Label | Label Description |
|---|---|---|
| Structural | PRES | Pressure |
| FREQ | Frequency (harmonic analyses only) | |
| Thermal | CONV[1] | Convection |
| HFLUX[1] | Heat flux | |
| RAD | Radiation | |
| RDSF | Surface-to-surface radiation | |
| Fluid | FSI[2] | Fluid-structure interaction flag |
| IMPD | Impedance boundary flag | |
| Electric | CHRGS | Surface charge density |
| MXWF | Maxwell force flag | |
| Magnetic | MXWF | Maxwell force flag |
| Acoustic fluid | FSI[2] | Fluid-structure interaction flag |
| IMPD | Impedance or admittance coefficient | |
| SHLD | Surface normal velocity or acceleration | |
| MXWF | Maxwell surface flag or equivalent source surface | |
| FREE | Free surface flag | |
| INF | Exterior Robin radiation boundary flag | |
| PORT | Port number | |
| ATTN | Attenuation coefficient | |
| BLI | Viscous-thermal boundary layer surface flag | |
| Field-surface interface | FSIN | Field-surface interface number |
| Poromechanics | FFLX | Fluid flow flux |
| Infinite element | INF | Exterior surface flag for INFIN110 and INFIN111 |
| Substructure | SELV[3] | Load vector number |
| Diffusion | DFLUX | Diffusion flux |
KVALValue key. If Lab = PRES:
0 or 1 | — |
|
2 | — |
|
Value key. If Lab = CONV:
0 or 1 | — | For thermal analyses, |
2 | — | For thermal analyses, |
3 | — |
|
4 | — |
|
Value key. If Lab = SHLD:
0 or 1 | — | For acoustics, |
2 | — | For acoustics, |
Value key. If Lab = RAD:
0 or 1 | — |
|
2 | — |
|
Value key. If Lab = RDSF:
0 or 1 | — |
|
2 | — |
|
Value key. If Lab = SELV:
0 or 1 | — |
|
2 | — |
|
Value key. If Lab = IMPD:
0 or 1 | — | For acoustic harmonic analyses, VAL1 through VAL4 are used as the real part of the impedance. |
2 | — | For acoustic harmonic analyses, VAL1 through VAL4 are used as the imaginary part of the impedance. |
If only one set of data is supplied, the other set of data defaults to previously specified values (or zero if not previously specified) in the all of the following cases:
Emissivities are supplied and Lab = RAD
Temperatures are supplied and Lab = RAD
Temperatures are supplied and Lab = CONV
Film coefficients are supplied and Lab = CONV
Normal velocity/acceleration for acoustics is supplied
and Lab = SHLD
Phase angle for acoustics is supplied and Lab = SHLD
VAL1First surface load value (typically at the first node
of the face) or the name of a table for specifying tabular boundary
conditions. Face nodes are listed in the order given for "Surface
Loads" in the input data table for each element type in the Element Reference.
For example, for SOLID185, the item 1-JILK
associates LKEY = 1 (face 1) with nodes
J, I, L, and K. Surface load value VAL1 then applies to node J of face 1. To specify a table, enclose the
table name in percent signs (%), e.g., %tabname%. Use the *DIM command to define a table. Only
one table can be specified, and it must be specified in the VAL1 position; tables specified in the VAL2, VAL3, or VAL4 positions will be ignored. VAL2 applies to node I, etc.
If Lab = PRES and KVAL = 2, VAL1 is the imaginary pressure, which is used only by SURF153, SURF154, SURF156, or SURF159 in full harmonic analyses (HROPT,FULL), or by a mode-superposition harmonic analysis
(HROPT,MSUP) if the mode-extraction method is Block
Lanczos (MODOPT,LANB), PCG Lanczos (MODOPT,LANPCG), Supernode (MODOPT,SNODE), or Subspace
(MODOPT,SUBSP).
If Lab = CONV,
KVAL = 0 or 1, and VAL1 = -N, the film coefficient is assumed to be a function of temperature
and is determined from the HF property table for material N [MP]. (See the SCOPT command for a way
to override this option and use -N as the film
coefficient.) The temperature used to evaluate the film coefficient is usually the average
between the bulk and wall temperatures, but may be user-defined for some elements.
If Lab = PORT, VAL1 is a port number representing a waveguide port. The port number
must be an integer between 1 and 50. For acoustic 2×2 transfer
admittance matrix, the port number can be any positive integer. The
smaller port number corresponds to the port 1 of the 2×2 transfer
admittance matrix and the greater port number corresponds to the port
2. If one port of the transfer admittance matrix is connecting to
the acoustic-structural interaction interface, the port number corresponds
to the port 2 of the transfer admittance matrix. A pair of ports of
the 2×2 transfer admittance matrix must be defined in the same
element.
If Lab = RDSF, KVAL = 0 or 1, and VAL1 = -N, the emissivity is assumed to be a function
of the temperature, and is determined from the EMISS property table
for material N (MP). The material N does not
need to correlate with the underlying solid thermal elements. If Lab = RDSF, KVAL = 2, and VAL1 is negative, radiation direction is reversed and
will occur inside the element for the flagged radiation surfaces.
If Lab = FSIN in a Multi-field solver
(single or multiple code coupling) analysis, VAL1 is the surface interface number. KVAL is not used. If Lab = FSIN in a unidirectional
ANSYS-to-CFX analysis, VAL1 is not used
unless the ANSYS analysis is performed using the Multi-field solver.
If Lab = SELV, VAL1 represents the scale factor (default = 0.0).
If Lab = ATTN, VAL1 is the attenuation coefficient.
VAL2, VAL3, VAL4Surface load values at the 2nd, 3rd, and 4th nodes
(if any) of the face. If all three values are blank, all three default
to VAL1, giving a constant load. Zero or
other blank values are used as zero. If a table is specified in VAL1, then any tables or numerical values specified
in VAL2, VAL3, or VAL4 will be ignored.
If Lab = FSIN in a unidirectional ANSYS
to CFX analysis, VAL2 is the surface interface
number (not available from within the GUI). VAL3 and VAL4 are not used.
Specifies surface loads on selected elements.
Caution: You cannot use the SFE command with
the INFIN110 or INFIN111 elements without prior knowledge of element face orientation, i.e.,
you must know which face is the exterior in order to flag it. Also,
the surface effect elements, SURF153 and SURF154, use LKEY to allow
the use of tangential and other loads (see SURF153and SURF154 of the Element Reference for more details).
Tapered loads may be applied over the faces of most elements.
For beam elements allowing lateral surface loads that may be offset from the nodes, use the SFBEAM command to specify the loads and offsets. See the SF command for an alternate surface load definition capability based upon node numbers. See the SFGRAD command for an alternate tapered load capability. Use the SFCUM command to accumulate (add) surface loads applied with SFE.
The SFE command can also be used to define
fluid pressure penetration loads (Lab =
PRES) at a contact interface. For this type of load, LKEY = 1 is used to specify the pressure values and LKEY = 2 is used to specify starting points and penetrating
points. See Applying Fluid Penetration Pressure in the Contact Technology Guide for details on how to apply this type of
load.
Film effectiveness and free stream temperatures specified with Lab = CONV are only valid for SURF151 and SURF152. Film effectiveness must be
between 0 and 1 and it defaults to 0. If film effectiveness is applied,
bulk temperature is ignored. When film effectiveness and free stream
temperatures are specified, the commands to specify a surface load
gradient (SFGRAD) or surface load accumulation
(SFCUM) are not valid. For more information on
film effectiveness, see Conduction and Convection in the Mechanical APDL Theory Reference.
You can specify a table name only when using structural (PRES) and thermal (CONV [film coefficient, bulk temperature, film effectiveness, and free stream temperature], HFLUX), diffusion flux (DFLUX), surface emissivity and ambient temperature (RAD), impedance (IMPD), normal velocity or acceleration (SHLD), attenuation coefficient (ATTN), and substructure (SELV) surface load labels.
When a tabular function load is applied to an element, the load will not vary according to the positioning of the element in space.
For cases where Lab=FSI, MXWF, FREE, and INF, VALUE is not needed.
This command is also valid in PREP7 and in the /MAP processor.