PRAS,
Lab
, LDSTEP
,
SUBSTEP
, FREQB
,
FREQE
, LogOpt
,
--
, VAL1
, VAL2
,
VAL3
, VAL4
,
VAL5
, VAL6
Prints a specified acoustic quantity during postprocessing of an
acoustic analysis.
Lab
The acoustic quantity to calculate:
SIMP | — | Specific acoustic impedance on the selected surface. |
AIMP | — | Acoustic impedance on the selected surface. |
MIMP | — | Mechanical impedance on the selected surface. |
PRES | — | Average pressure on the selected surface. |
FORC | — | Force on the selected surface. |
POWE | — | Acoustic power on the selected surface. |
ERP | — | Equivalent radiated power on the selected structural surface (valid only for SHELL181, SOLID185, SOLID186, SOLID187, SOLSH190 and SHELL281). |
ERPL | — | Equivalent radiated power level on the selected structural surface (valid only for SHELL181, SOLID185, SOLID186, SOLID187, SOLSH190 and SHELL281). |
BSPL | — | Frequency-band sound pressure level on selected nodes. |
BSPA | — | A-weighted frequency-band sound pressure level on selected nodes. |
MENE | — | Acoustic potential energy on the selected elements. |
KENE | — | Acoustic kinetic energy on the selected elements. |
TENE | — | Acoustic total energy on the selected elements. |
PL2V | — | Average square of the L2 norm of pressure on the selected elements. |
LWIN | — | Input sound power level on defined port. |
LWOUT | — | Output sound power level on defined driven port. |
RL | — | Return loss on defined port. |
ALPHA | — | Absorption coefficient on defined port. |
TL | — | Transmission loss on defined ports. |
PALL | — | All port-related parameters (LWIN, LWOUT, RL, ALPHA, TL). |
DFSTL | — | Transmission loss of random acoustic analysis. |
DFSPW | — | Radiated power in random acoustic analysis. |
DALL | — | All random acoustic related parameters (DFSTL, DFSPW). |
LDSTEP
Specified load step. Defaults to the load step number specified on the
SET command, or defaults to 1 if SET has not been
issued. This default applies to all Lab
values except DFSTL, DFSPW,
and DALL.
| — | Load step number. |
ALL | — | All load steps. |
AVG or 0 | — | Average result of multiple samplings in a random acoustic analysis (see the
MSOLVE command). This option is used only for
|
SUBSTEP
Specified substep. Defaults to the substep number specified on the SET
command, or defaults to ALL (all substeps at the specified load step) if
SET has not been issued. For Lab
= BSPL or
BSPA, ALL is the only valid value.
| — | Substep number. |
ALL | — | All substeps. |
FREQB
Frequency value representing one of the following:
Beginning frequency of the frequency range (FREQB
to
FREQE
) for the defined load step(s) and substeps
(SUBSTEP
= ALL). If a SUBSTEP
value
is specified, FREQB
is invalid.
Central frequency of octave bands, used when LogOpt
= OB1,
OB2, OB3, OB6, OB12, or OB24 and FREQE
is blank.
FREQE
Ending frequency of the frequency range (FREQB
to
FREQE
) for the defined load step(s) and sub-steps
(SUBSTEP
= ALL). If blank, FREQE
is set
to FREQB
. If a SUBSTEP
value is
specified, FREQE
is invalid.
LogOpt
Octave bands:
OB0 | — | Narrow bands (default). |
OB1 | — | Octave bands. |
OB2 | — | 1/2 octave bands. |
OB3 | — | 1/3 octave bands. |
OB6 | — | 1/6 octave bands. |
OB12 | — | 1/12 octave bands. |
OB24 | — | 1/24 octave bands. |
--
Unused field.
VAL1
Input port number for Lab
= LWIN, LWOUT, RL, ALPHA, TL, or
PALL.
VAL2
Output port number for Lab
= TL or PALL.
VAL3
Reference power for Lab
= LWIN, LWOUT, PALL or EPRL (defaults
to 1x10-12 W).
VAL4
Fluid mass density for Lab
= ERP or ERPL (defaults to 1.2041
kg/m3).
VAL5
Speed of sound in the fluid for Lab
= ERP or ERPL (defaults to
343.25 m/s).
VAL6
Radiation efficiency for Lab
= ERP or ERPL (defaults to
1).
The PRAS command lists the specified acoustic quantity on the selected exterior surface, the energy on selected elements, or the sound pressure level over frequency bands. The calculation is based on the pressure and velocity solution or the frequency-band sound pressure level (SPL).
The total pressure and velocity are used if the selected surface is the excitation source surface. To calculate the incoming and outgoing acoustic power and other sound power parameters on the input and output surfaces, issue the SF,,PORT command in the preprocessor to define port numbers.
The sound pressure level of the octave bands and general frequency band (defined via the HARFRQ command) is calculated at the selected nodes in the model.