*HEADING
 Elastic body problem, C3D8 
 The "structure" alone has a frequency of 1.0 Hz
**
*RESTART, READ, STEP=1,  END STEP, WRITE, FREQUENCY=4
**
** Step 2
**
*STEP, INC=400
*DYNAMIC, ALPHA=0.0,INITIAL=NO
 0.025, 2.0
*INCIDENT WAVE, PRESSUREAMPLITUDE=PRES,PROPERTY=USA
 SOLID,1.0
*INCIDENT WAVE, PRESSUREAMPLITUDE=PRES,PROPERTY=USA
 FLUID,1.0
*SIMPEDANCE
 PLANE,
**
***NODE FILE, NSET=NODE2, FREQUENCY=1
** V,
*OUTPUT,FIELD,FREQ=1
*NODE OUTPUT,NSET=FRONT_F
 POR,
*NODE OUTPUT,NSET=NODE2
 U,V,
*OUTPUT,HISTORY,FREQ=1
*NODE OUTPUT,NSET=FRONT_F
 POR,
*NODE OUTPUT,NSET=NODE2
 U,V,
*END STEP