ACCELERATION

I/O Options and Subcase Information Entry The ACCELERATION command can be used in the I/O Options or Subcase Information sections to request acceleration vector output for all s or individual s, respectively.

Format

ACCELERATION(sorting,format,form,rotations,random,peakoutput,fourier,type,statistics) = option

Definitions

Argument	Options	Description
`sorting`	<SORT1, SORT2> Default = blank	This argument only applies to the PUNCH format (.pch file) or the OUTPUT2 format (.op2 file) output for normal modes, frequency response, and transient s. It will be ignored without warning if used elsewhere. SORT1 Results for each frequency/timestep are grouped together. SORT2 Results for each grid/element are grouped together. 8 blank For Frequency Response Analysis, if grid SET is not specified, SORT1 is used, otherwise, SORT2 is used; for Transient Analysis, SORT2 is used.
`format`	<HM, H3D, HG, OPTI, PUNCH, OP2, PLOT, blank>	HM Results are output in HyperMesh results format (.res file). H3D Results are output in Hyper3D format (.h3d file). HG Results are output in HyperGraph presentation format (_freq.mvw file and _tran.mvw file) - see OUTPUT keywords HGFREQ and HGTRANS. OPTI Results are output in OptiStruct results format (.disp file). PUNCH Results are output in Nastran punch results format (.pch file). OP2 Results are output in Nastran output2 format (.op2 file) PLOT Results are output in Nastran output2 format (.op2 file) when PARAM,POST is defined in the Bulk Data section. If PARAM, POST is not defined in the Bulk Data section, this format allows the form for complex results to be defined for XYPUNCH output without having other output. blank (Default) Results are output in all active formats for which the result is available.
`form`	<COMPLEX, REAL, IMAG, PHASE, BOTH> Default (HM only) = COMPLEX Default (all other formats) = REAL	COMPLEX (HM only), blank Provides a combined magnitude/phase form of complex output to the .res file for the HM output format. REAL or IMAG Provides rectangular format (real and imaginary) of complex output. 9 PHASE Provides polar format (magnitude and phase) of complex output. Phase output is in degrees.9 BOTH (HM only) Provides both polar and rectangular formats of complex output.
`rotations`	<ROTA, NOROTA>	ROTA Requests output of rotational acceleration results (in addition to translational acceleration results). NOROTA (Default) Rotational acceleration results are not output.
`random`	<PSDF, RMS, PSDFC> No default	PSDF Requests PSD and RMS results from Random Response Analysis to be output. Only valid for the H3D format. The "RMS over Frequencies" output is at the end of the random results. RMS Requests only the “RMS over Frequencies” result from random response analysis to be output. Only valid for the H3D format. PSDFC Requests PSD, RMS and RMS (cumulative) results from random response analysis to be output. Only valid for the H3D format. The "RMS over Frequencies" output is at the end of the random results.
`peakoutput`	<PEAKOUT> Default = blank	If PEAKOUT is present, only the filtered frequencies from the PEAKOUT card will be considered for this output.
`type`	<NORMAL>	NORMAL If present, the normal acceleration results for grids on the surface of shell and solid elements are output. 12 blank (Default) Normal acceleration results are not output.
`Fourier`	<FOURIER> Default = blank	Accelerations are output for Modal Transient Response Analysis with Fourier Transformation. FREQ Frequency domain. 13 TIME Time domain. 13
`statistics`	<STATIS, OSTATIS, or blank>	Results of Acceleration Statistics over time in a Transient Analysis are controlled by this option. 14 STATIS Acceleration Statistics are output in addition to regular acceleration output at each timestep. OSTATIS Only the Acceleration Statistics are output. blank (Default)
`option`	<YES, ALL, NO, NONE, SID> Default = ALL	YES, ALL, blank Acceleration is output for all nodes. NO, NONE Acceleration is not output. SID If a set ID is given, acceleration is output only for nodes listed in that set.

Comments

When the ACCELERATION command is not present, acceleration results are not output.
Acceleration output is only available for Frequency Response, Transient Analysis, and Response Spectrum solution sequences.
The form argument is only applicable for Frequency Response Analysis. It is ignored for other analysis types.
The forms BOTH and COMPLEX do not apply to the .frf output files.
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. See Results Output by OptiStruct for information on the results available and their respective formats.
Multiple instances of this card are allowed; if instances are conflicting, the last instance dominates.
For optimization, the frequency of output to a given format is controlled by the I/O option OUTPUT.
In general, HyperView does not recognize the SORT2 format for results from the .op2 file. When results are output only in SORT2 format (<Result Keyword> (SORT2, OUTPUT2, ...)), the results are written by OptiStruct into the .op2 file in SORT2 format, but when the .op2 file is imported into HyperView, the results in SORT2 format are not recognized. Therefore, the SORT1 option is recommended for results output in OUTPUT2 format and SORT2 option is recommended for results output in PUNCH format.
Results in binary format (.h3d or .op2) are always output in PHASE/MAG form, regardless of the options specified in the FORM field. The corresponding post-processors (HyperView/HyperGraph) can easily convert the PHASE/MAG format to the required formats. Results in ASCII formats are output in the specified/requested FORM.
The abbreviations ACCE and ACCEL are interchangeable with ACCELERATION.
format=OUTPUT2 can also be used to request results to be output in the Nastran output2 format (.op2 file).
For NORMAL acceleration output, the surface grids are automatically selected from within the specified GRID SET. Alternately, if option=ALL is input, the normal acceleration is output for all surface grids in the model. Normal results are only available for Frequency Response Analysis and in the H3D format.
The FREQ and TIME options are only valid for Modal Transient Analysis with Fourier transformation. When FREQ is present, the accelerations in frequency domain would be output in a dummy frequency , which shares the same ID with the transient .
Acceleration Statistics are supported for Direct and Modal Linear Transient Analysis types.
Only H3D output is supported for Acceleration Statistics.

The following statistics over time are output for Transient Analysis when STATIS or OSTATIS is specified with Acceleration.

Statistics

Supported Acceleration Result Types

Minimum and Time of Minimum

X-component, Y-component, Z-component

Maximum and Time of Maximum

Magnitude, X-component, Y-component, Z-component

Absolute Maximum and Time of Absolute Maximum

X-component, Y-component, Z-component

Arithmetic Mean, Root Mean Square (RMS), Variance, and Standard Deviation

Magnitude, X-component, Y-component, Z-component

The acceleration statistics can be viewed in HyperView after loading the H3D file, under Statistics over time option at the end of the timestep list in the Results Browser. Then, various statistics can be chosen from the sub-menu under Acceleration (Statistics) (s).

Figure 1.