FOS

I/O Options and Subcase Information Entry The FOS command can be used in the I/O Options or Subcase Information sections to request fatigue factor of safety, hydrostatic pressure, and shear stress output for all fatigue subcases or individual fatigue subcases.

Format

FOS (format, type, option, THRESH=thresh, RTHRESH=rthresh, TOP=topn, RTOP=rtop) = option

Definitions

Argument Options Description
format <H3D, OPTI, blank>
H3D
Results are output in Hyper3D format (.h3d file).
OPTI
Results are output in OptiStruct results format (.fat file).
blank (Default)
Results are output in all active formats for which the result is available.
type <SUB, EVENT>
SUB (Default)
Total FOS, hydrostatic pressure, and shear stress results are output for Fatigue Subcases.
EVENT
FOS, hydrostatic pressure, and shear stress results are output for each FATEVNT in addition to results output via the SUB option.
option <HISTORY, blank> Factor of Safety, Hydrostatic Pressure, and Microscopic Shear Stress results are output as a function of time for Fatigue subcases.
HISTORY
Currently only supported for type=EVENT.
blank (Default)
THRESH <thresh>

Default = blank (Real)

 Specifies an absolute threshold under which FOS results should not be output.
RTHRESH <rthresh>

Default = blank (0.0 < Real < 1.0)

 Specifies a relative threshold as a fraction of the total FOS under which results should not be output. For example, if F is the total FOS in the model, then FOS results below F*rthresh are excluded from the output.
TOP <topn>

Default = blank (Integer > 0)

 Only the top “topn” FOS values should be output
RTOP <rtopn>

Default = blank (0.0 < Real < 1.0)

 Only the top fraction (“rtop”) of the total number of FOS values should be output. For example, if FTOT is the total number of FOS values in the model, then only the top FTOT*rtop values are output.
option <YES, ALL, NO, NONE, SID, PSID>

Default = ALL
YES, ALL, blank
Results are output for all elements.
NO, NONE
Results are not output.
SID
If a set ID is provided, results are output only for elements listed in that set.
PSID
If a property set ID is provided, results are output only for elements referenced by the corresponding set of properties (SET (TYPE=ELEM, SUBTYPE=PROP)).

Comments

  1. When a FOS command is not present, fatigue FOS results are not output.
  2. Multiple formats are allowed on the same entry; these should be comma separated. If a format is not specified, this output control applies to all formats defined by the OUTPUT command, for which the result is available.
  3. Hydrostatic Pressure and Shear Stress are not output in the OPTI format. Only Event-based FOS results are output in OPTI format. The H3D format supports full output.
  4. Center of the yield surface is determined based on the entire load history across multiple events. Therefore, the FOS of an event is affected by the entire load history and not just the local load history of the event.
  5. Multiple instances of this card are allowed; if instances are conflicting, the last instance dominates.
  6. For Fatigue subcases with gid-based FATDEF, the GPFOS entry should be used to request FOS output.