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, statistics, MPF=mpf, MFILTER=mfilter, FREQUENCY/SOLUTION=frequency ) = option
Definitions
Argument  Options  Description 

format  H3D, PUNCH, blank 

grid  GRID Default = blank 

peakoutput  PEAKOUT Default = blank 
If present, then only the filtered frequencies from the PEAKOUT card will be considered for this output. 
statistics  STATIS,
OSTATIS Default = blank 
ERP Statistics over time in linear transient analysis and
steadystate analysis are controlled by this option. 12

mpf  ALL, <N> Default = blank 

frequency  <SETID> Default = blank 

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 

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.$$ERP=ERPRLF*\left(\frac{1}{2}ERPC*ERPRHO\right){\displaystyle \sum _{i}^{ngrid}{A}_{i}{v}_{i}^{2}}$$
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.
$${\left(ERP\right)}_{i}=ERPRLF\left(\frac{1}{2}ERPC\times ERPRHO\right){A}_{i}{v}_{i}^{2}$$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:$${\mathit{ERP}}_{\mathit{dB}}=10{\text{log}}_{10}\left(\mathit{RHOCP}*\frac{\mathit{ERP}}{\mathit{ERPREFDB}}\right)$$
 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 SteadyState Analysis.
 ERP Statistics are only supported for
direct and modal linear transient analysis, and steadystate analysis. Only H3D
output is currently supported. The following statistics over time are output
when STATIS or OSTATIS is specified:
 Maximum
 Time of Maximum
 Arithmetic Mean
 RMS
 Variance
 Standard Deviation