ansys.mapdl.core.Mapdl.pras#

Mapdl.pras(lab='', ldstep='', substep='', freqb='', freqe='', logopt='', val1='', val2='', val3='', val4='', val5='', val6='', **kwargs)#

Prints a specified acoustic quantity during postprocessing of an acoustic analysis.

Mechanical APDL Command: PRAS

Parameters:
labstr

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, SOLID225, SOLID226, SOLID227, and SHELL281 ).

  • ERPL - Equivalent radiated power level on the selected structural surface (valid only for SHELL181, SOLID185, SOLID186, SOLID187, SOLSH190, SOLID225, SOLID226, SOLID227, 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).

ldstepstr

Specified load step. Defaults to the load step number specified on the Set displays command, or defaults to 1 if Set displays has not been issued. This default applies to all Lab values except DFSTL, DFSPW, and DALL.

  • n - 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 Lab = DFSTL, DFSPW, and DALL, and it is the default for these labels.

substepstr

Specified substep. Defaults to the substep number specified on the Set displays command, or defaults to ALL (all substeps at the specified load step) if Set displays has not been issued. For Lab = BSPL or BSPA, ALL is the only valid value.

  • n - Substep number.

  • ALL - All substeps.

freqbstr

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.

freqestr

Ending frequency of the frequency range ( FREQB to FREQE ) for the defined load step(s) and substeps ( SUBSTEP = ALL). If blank, FREQE is set to FREQB. If a SUBSTEP value is specified, FREQE is invalid.

logoptstr

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.

val1str

Input port number for Lab = LWIN, LWOUT, RL, ALPHA, TL, or PALL.

val2str

Output port number for Lab = TL or PALL.

val3str

Reference power for Lab = LWIN, LWOUT, PALL or EPRL (defaults to 1x10 -12 W).

val4str

Fluid mass density for Lab = ERP or ERPL (defaults to 1.2041 kg/m 3 ).

val5str

Speed of sound in the fluid for Lab = ERP or ERPL (defaults to 343.25 m/s).

val6str

Radiation efficiency for Lab = ERP or ERPL (defaults to 1).

Notes

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.