PEAKOUT

Bulk Data Entry Defines criteria used for the automatic identification of loading frequencies at which result peaks occur. Other result output may then be requested at these "peak" loading frequencies. This feature is only supported for frequency response solution sequences.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PEAKOUT SID NPEAK NEAR FAR LFREQ HFREQ RTYPE PSCALE
GRIDC GID1 CID1 CUTOFF1 GID2 CID2 CUTOFF2
GID1 CID1 CUTOFF4
GID3 CID3 CUTOFF3 etc etc etc
PANEL PID1 GID1 CUTOFF1
PID2 GID2 CUTOFF2
MODE SENAME1 MODID1 CUTOFF1 ETYPE
SENAME2 MODID2 CUTOFF2 ETYPE
etc. etc.

Example 1

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PEAKOUT 396 5 0.5 100.0 0.0 200.0 DISP DB
GRIDC 65 1 11 66 1 10
67 1 11 68 1 11

Example 2

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PEAKOUT 396 5 0.5 100.0 0.0 200.0 CMSE
MODE AX TOTAL 11
AX 3 11 PEAK

Definitions

Field Contents SI Unit Example
SID Set identification number.

No default (Integer > 0)
NPEAK Desired number of peaks. 2

Default = 5 (Integer > 0)
NEAR Minimum allowed distance between two peaks. If two peaks are closer than this value, the loading frequency of the lower peak will be ignored. 2

Default = 0.0 (Real ≥ 0.0)
FAR Maximum allowed distance between two peaks. Additional peaks will be selected (in addition to NPEAK) if the distance between the peaks is greater than this value. 2

Default = largest applied loading frequency (Real ≥ 0.0)
LFREQ Starting loading frequency for peak identification. 2

Default = 0.0 (Real ≥ 0.0)
HFREQ Ending loading frequency for peak identification. 2

Default = largest applied loading frequency (Real ≥ 0.0)
RTYPE Result type for peak identification for the structural domain.
The result for a type can be displacement, velocity, acceleration, equivalent radiated power, modal energy, or CMS energy. For DISP, the pressure response at far-field microphone degrees-of-freedom for APML analysis is also supported.
DISP (Default)
VELO
ACCE
ERP
MODALSE
MODALKE
MODALDE
CMSE
CMKE
CMDE
PSCALE Pressure scaling method for peak identification for both structural and the fluid domains.

PSCALE is only available for RTYPE = DISP, VELO, or ACCE.

The result for a structural or fluid grid can be the scale of pressure, decibels (DB) or A-weighted decibels (DBA). See comment 3 for decibel calculations and reference pressure settings. For DBA, standard A-weighting is used.

Default = DBA (DB, DBA or NONE)
GRIDC Indicates that a degree-of-freedom list for peak identification is to follow.

GRIDC is only available for RTYPE=DISP, VELO, or ACCE.
GID# Grid identification number.

No default (Integer > 0)
CID# Component identification number.

No default (1 ≤ Integer ≤ 6)
PANEL Flag indicating that an ERP response list for peak identification is to follow.

This is only available when RTYPE=ERP. Either PID or GID can be used in the list to request ERP of a panel or a grid.
PID# Panel identification number for the ERP response.

No default (Integer > 0)
GID# Grid identification number for the ERP response.

No default (Integer > 0)
MODE Flag indicating that a CMS energy response list for peak identification is to follow.

This is only available when RTYPE=CMSE, CMKE, CMDE, MODALSE, MODALKE or MODALDE.
SENAME# The label of a super element. This is required when RTYPE=CMSE, CMKE or CMDE.

No default (Character string)

MODID# Mode identification number.
TOTAL (Default)
Request the total energy.
Integer > 0
ETYPE
AVG (Default)
Average of the energy.
AMPL
Amplitude of the energy is output.
PEAK
Peak energy (the sum of average and amplitude).
CUTOFF# The cutoff value can be a real value or an integer value. 2

If the entry is a real value, then this is the value of the cutoff (in the same unit specified by RTYPE and PSCALE).

If the entry is an integer value, then this is the identification number of a TABLED1, TABLED2, TABLED3, or TABLED4 entry defining the cutoff as a function of frequency (in the same unit specified by RTYPE and PSCALE).

Default = 0.0 (Real or Integer > 0)

Comments

  1. There can be multiple PEAKOUT cards with the same SETID.
  2. The following example shows how the different criteria work in identifying peaks.
    Figure 1. Plot of the Acoustic Response versus Frequency

    peakout_peaks

    Figure 1 shows a plot of the Acoustic Response versus frequency for a chosen degree-of-freedom. The total frequency range can be reduced to the frequency range of interest by defining LFREQ and HFREQ. The search area can be further reduced by defining CUTOFF such that low magnitude peaks can be ignored. In the remaining region, 5 peaks (P1, P2, P3, P4, and P5) can easily be identified. Should NPEAK be set to 4, the resulting frequency set would consist of the frequencies corresponding to the peaks P4, P2, P1, and P3, with P5 being omitted.

    In order to ensure that peaks are neither too far apart nor too close together, the FAR and NEAR criteria, respectively, may be used.

    In the above example, should a value of 50HZ be defined for FAR, P4 would be selected in addition to the other peaks because D2 (~54 Hz) is greater than 50Hz, and so an additional peak is required to satisfy the FAR criterion.

    Similarly, should a value of 15Hz be defined for NEAR, then P2 will be omitted, as D1 (~11 Hz) is less than 15Hz.

  3. The dB value is calculated using 20 * log10 (P/P0), where P0 is the reference pressure. The reference pressure is dependent on the units specified on the UNITS input data. If the units are SI, the value is set as 2.0E-5 Pa. If they are CGS, it is set as 2.0E-4 barye. If they are MPa, it is set as 2.0E-11 MPa. If they are BG or EE, then it is set as 4.17E-7 lbf/ft2. If no UNITS data is present, the default value is 2.0E-11 MPa.
  4. If you want to include interior points of a superelement (in a CMS model) for the purposes of peak identification using the PEAKOUT Bulk Data Entry, the SEINTPNT entry can be used in the Subcase Information section to convert the interior grid points to exterior grid points (since points referenced by PEAKOUT should be exterior points only).
  5. Definition of multiple PEAKOUT for the same DOF (GID# and CID#) is now supported.