FOS

I/O Options and Subcase Information Entry Used to request fatigue factor of safety, hydrostatic pressure, and shear stress output for all fatigue subcases or individual fatigue subcases. It also controls the output of Safety Factor (SF) from SN Fatigue Analysis.

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

When a FOS command is not present, fatigue FOS results are not output.
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.
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.
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.
Multiple instances of this card are allowed. If instances are conflicting, the last instance dominates.
For Fatigue subcases with grid-based FATDEF, the GPFOS entry should be used to request FOS output.
FOS I/O Option Entry is also required to activate Safety Factor (SF) output for SN Fatigue analysis. For more information, refer to the SFANAL continuation line on the FATPARM Bulk Data Entry.