ERP

I/O Options and Subcase Information Entry Used to request equivalent radiated power output for all subcases or individual subcases, respectively.

Format

ERP (format_list, grid, peakoutput,MPF=mpf, MFILTER=mfilter, FREQUENCY/SOLUTION=frequency ) = option

Definitions

Argument	Options	Description
`format`	H3D, PUNCH, blank	H3D Results are output in Hyper3D format (.h3d file). PUNCH Results are output in Nastran punch results format (.pch file). 10 blank (Default) Results are output in all active formats for which the result is available.
`grid`	GRID Default = blank	GRID Output the contribution of each grid in addition to the ERP results for the PANEL, defined by ERPPNL or PANELG (`TYPE`=ERP). 5
`peakoutput`	PEAKOUT Default = blank	If present, then only the filtered frequencies from the PEAKOUT card will be considered for this output.
`mpf`	ALL, <N> Default = blank	ALL Modal Participation Factors are output for ALL modes. <N> Modal Participation Factors are output for the specified <N> modes. (Integer)
`frequency`	<SETID> Default = blank	<SETID> Indicates the SET of loading frequencies for which Modal Participation Factors should be output. If not specified, then Modal Participation Factors are output for all loading frequencies. (Integer)
`mfilter`	<Real> Default = blank	Provides a threshold under which Modal Participation Factors are not output. Output is skipped when the Modal Participation Factor divided by the maximum Modal Participation Factor (for the current mode) is below the threshold specified by MFILTER.
`option`	<YES, ALL, NO, NONE> Default = ALL	YES, ALL, blank Equivalent radiated power is output for all panels. For PUNCH file format, in addition to ERP output for each panel, the total ERP for all panels is also output. For PUNCH file format, the corresponding panel area is also output. NO, NONE Equivalent radiated power is not output.

Comments

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.
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 addition to the ERP values, the following results are output to the .pch file: total ERP over the loading frequencies, fraction of the total ERP at each loading frequency, and ERP expressed in decibels. 6
The ERP output of a panel is calculated, as shown in Equation 2. The parameters for the speed of sound (ERPC), fluid density (ERPRHO), and radiation loss factor (ERPRLF) are used in the calculation of ERP.
(1)
$E R P = E R P R L F * (\frac{1}{2} E R P C * E R P R H O) \sum_{i}^{n g r i d} A_{i} v_{i}^{2}$

The ERP output of a grid point ( $i$ ) is also calculated similar to that of a panel (as shown above). The parameters for the speed of sound (ERPC), fluid density (ERPRHO), and radiation loss factor (ERPRLF) are used in the calculation of ERP output for a particular grid.(2)
${(E R P)}_{i} = E R P R L F (\frac{1}{2} E R P C \times E R P R H O) A_{i} v_{i}^{2}$

Where,

$v_{i}$

Normal velocity

$A_{i}$

Associate area of each grid on the panel
The calculation of ERP in decibels (dB) is performed using the PARAM data RHOCP and ERPREFDB in Equation 3. The ERP output in dB format is currently only output in PUNCH format. ERPREFDB is the reference value in dB and RHOCP is the scale factor:(3)
${ERP}_{dB} = 10 {log}_{10} (RHOCP * \frac{ERP}{ERPREFDB})$
At least one of the Bulk Data Entries ERPPNL or PANELG (TYPE=ERP) needs to be specified, if the ERP Output Request is used.
Modal Participation Factor output for Equivalent Radiated Power is supported in PUNCH and H3D files. Either FREQUENCY or SOLUTION can be used as the keyword to indicate the loading frequency set.
The direction of normals of elements selected as a panel for ERP output should be consistent. OptiStruct will automatically flip normals of elements which have inconsistent normals if such elements belong to panels selected for ERP output.
For PUNCH file format, the total ERP of all panels is output. The corresponding area of each panel is also output in the PUNCH file.
ERP output ERP is supported for Direct Frequency Response, Modal Frequency Response, Direct Transient Response, Modal Transient Response, Complex Eigenvalue Analysis, and Steady-State Analysis.