A large deflection (NLGEOM,ON) static analysis is performed to insert tensile stress in the membrane with an applied temperature and to introduce a DC voltage on the membrane side of the air gap.

Acoustic elements are ignored in this analysis, but the MORPH command is used to morph acoustic elements so that they are properly shaped for the downstream linear perturbation analysis. Setting StrOpt = YES on the MORPH command allows morphing in the model with structural elements:

MORPH,ON,,,,,,,,,YES

A frequency sweep is performed from 20 to 20,000 Hz with a logarithmic span option.

HARFRQ,20.0,20000.0,,LOG

In this harmonic response analysis, the linear perturbation method is used to include prestress effects; a DC bias voltage effect of 0.45 V is considered. An acoustic velocity is applied on the sound port inlet, which leads to the vibration of the membrane:

CMSEL,S,AIRPORT    ! Select the sound port inlet
ESEL,S,ENAME,,30
SF,ALL,SHLD,0.01, 0      ! Apply surface normal velocity

The linear perturbation method for full harmonic response analyses is described in Prestressed Harmonic Analysis in the Structural Analysis Guide.