*HEADING
1D TRANSIENT WAVE PROPAGATION IN AN ACOUSTIC MEDIUM WITH PRESCRIBED ACCEL
IN ABAQUS/EXPLICIT [AC3D4];
**
** C = root (K/rho)= 343.05 m/s   K=bulk mod, rho=density.  
**
** Analytic solution to prescribed constant acceleration of a0 at x=0
** 
** p(x,t) = (K a0 / c^2) (ct - x)  for x < ct
**        = 0  			   for x > ct
** 
*PREPRINT,ECHO=NO,HISTORY=NO,MODEL=no
*NODE, Nset=ODB_NSET
    1, 0,
  101, 1,
 1001, 0, 1e-2
 1101, 1, 1e-2
 1501, 0, 1e-2, -1e-2
 1601, 1, 1e-2, -1e-2
 2501, 0, 0, -1e-2
 2601, 1, 0, -1e-2
*NGEN,NSET=CHANNEL_NODES
    1,101
 1001,1101
 1501,1601
 2501,2601
*NSET,NSET=SAMPLE_NODES,GENERATE
 1,101
*NSET,NSET=NALL
ODB_NSET, CHANNEL_NODES, SAMPLE_NODES
*NODE,NSET=LOAD
10001, 0,
10002, 0, 1e-2
10003, 0, 1e-2, -1e-2
10004, 0, 0, -1e-2
10005, -0.1e-2,
10006, -0.1e-2, 1e-2
10007, -0.1e-2, 1e-2, -1e-2
10008, -0.1e-2, 0, -1e-2
*ELEMENT,TYPE=AC3D4
    1,    1, 1002,    2, 2501
    2, 1002,    2, 2501, 1502
    3,    2, 2501, 1502, 2502
    4,    1, 1001, 1002, 2501
    5, 1001, 1002, 2501, 1501
    6, 1002, 2501, 1501, 1502
*ELGEN,ELSET=CHANNEL
 1,100,1,6
 2,100,1,6
 3,100,1,6
 4,100,1,6
 5,100,1,6
 6,100,1,6
**
*SOLID SECTION,MATERIAL=AIR,ELSET=CHANNEL
*surface,NAME=NRS
 597,S4
 596,S2
**
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
 0.1424E6,
*ELEMENT,TYPE=C3D6,ELSET=LOAD
800, 10001, 10002, 10004, 10005, 10006, 10008
900, 10002, 10003, 10004, 10006, 10007, 10008
*SOLID SECTION,MATERIAL=MAT1,ELSET=LOAD
*MATERIAL,NAME=MAT1
*ELASTIC
 180E2,0.333333
*DENSITY
 76.70,
**
*********************************
*SURFACE,TYPE=ELEMENT,NAME=SECONDARY
4, S2
5, S4
*SURFACE,TYPE=ELEMENT,NAME=MAIN
800, S1
900, S1
*TIE,NAME=COUPLING
SECONDARY,MAIN
********************
*NSET, NSET=QA_TEST
ODB_NSET
**
*STEP
*DYNAMIC,EXPLICIT
,.0036
** Define nonreflective boundary at x=1
*IMPEDANCE
 597,I4,
 596,I2,
**
** Prescribe volume acceleration a0=1.
** Acceleration of interface element specified.
** In order to run single precision, the reference
** magnitude is increased to 1000.
**
*BOUNDARY,TYPE=ACCELERATION
LOAD,1,1,1.0E3
**
*OUTPUT,FIELD,NUMBER INTERVAL=1
*NODE OUTPUT
POR
*OUTPUT,HISTORY, FREQ=1
*NODE OUTPUT, NSET=QA_TEST
POR
*ENDSTEP
*STEP
*DYNAMIC,EXPLICIT
,.0008
** Define nonreflective boundary at x=1
*IMPEDANCE,OP=NEW
*SIMPEDANCE
NRS
**
*BOUNDARY,TYPE=ACCELERATION
LOAD,1,1,1.0E3
**
*OUTPUT,FIELD,NUMBER INTERVAL=1
*NODE OUTPUT
POR
*OUTPUT,HISTORY, FREQ=1
*NODE OUTPUT, NSET=QA_TEST
POR
*ENDSTEP