*HEADING
1D TRANSIENT WAVE PROPAGATION IN AN ACOUSTIC MEDIUM WITH CLOAD 
IN ABAQUS/EXPLICIT [ACAX3]; 
VERIFICATION PROBLEM: TRANSIENT DYNAMICS TESTS
**
** C=SQRT(K/RHO)= 343.05 M/S   K=BULK MODULUS, 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
** FOR EXAMPLE AT THE END OF THE SIMULATION : 
**              P_1(0,0.0044)=1.826
**              P_51(0.5,0.0044)=1.221
**              P_101(1.0,0.0044)=0.616
** THE ACCELERATION IS SPECIFIED USING *CLOAD ON DOF 8
**
** SEE CH. 3.7.7 OF ABAQUS/VERIFICATION MANUAL
**
*PREPRINT,ECHO=NO,HISTORY=NO,MODEL=NO
*NODE, NSET=NALL
    1, 0,
  101, 0, 1.,
  501, .5e-2,0.
  601, .5e-2,1.
 1001, 1.e-2,0.
 1101, 1.e-2,1.
*NGEN,NSET=NALL
    1,101
 1001,1101
*NSET,NSET=QA_TEST,GEN
1,10,1
45,55,1
90,101,1
*NSET,NSET=NOUT
QA_TEST,
*NSET,NSET=LOAD
 1,1001
*ELEMENT,TYPE=ACAX3
 1,1,1002,2
 2,1,1001,1002
*ELGEN,ELSET=CHANNEL
 1,100,1,2
 2,100,1,2
*SOLID SECTION,MATERIAL=AIR,ELSET=CHANNEL
 1.e-2, 
** Cross-section is 1.0e-4 * Pi
**
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
 0.1424E6,
**
*RESTART,WRITE,NUMBER=1
*STEP
*DYNAMIC,EXPLICIT
,.0044
** Define nonreflective boundary at z=1
*IMPEDANCE
 199,I2
**
**
** Prescribe volume acceleration inwards
**     of  a0=1.
**     Distribute to each node on edge according to:.
**  [1/3, 2/3] *area
*CLOAD
 1,8,1.04719755e-4
 1001,8,2.09439510e-4
**
*OUTPUT,FIELD,NUMBER INTERVAL=1
*NODE OUTPUT
POR
*NODE OUTPUT,NSET=QA_TEST
POR,
*************************
***OUTPUT,HISTORY, TIME INTERVAL=0.00022
***NODE OUTPUT, NSET=NOUT
**POR
*************************
*END STEP