*HEADING
1D TRANSIENT WAVE PROPAGATION IN AN ACOUSTIC MEDIUM WITH CLOAD 
IN ABAQUS/EXPLICIT [AC3D8R]; 
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, 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=NALL
    1,101
 1001,1101
 1501,1601
 2501,2601
*NSET,NSET=QA_TEST,GEN
1,10,1
45,55,1
90,101,1
*NSET,NSET=NOUT
QA_TEST,
*NSET,NSET=LOADED_NODES
 1,1001,1501,2501
*ELEMENT,TYPE=AC3D8R
 1,1,2,2502,2501,1001,1002,1502,1501
*ELGEN,ELSET=CHANNEL
 1,100
*SOLID SECTION,MATERIAL=AIR,ELSET=CHANNEL
**
*MATERIAL,NAME=AIR
*DENSITY
 1.21,
*ACOUSTIC MEDIUM,BULK MODULUS
 0.1424E6,
**
** Define nonreflective boundary at x=1
** Using user calculated constants:
** 1/k1=0, 1/c1=1/(rho*c)
*IMPEDANCE PROPERTY,NAME=NONREF
 0, 2.41E-3
**
*RESTART,WRITE,NUMBER=1
*STEP
*DYNAMIC,EXPLICIT
,.0044
** Define nonreflective boundary at x=1
*IMPEDANCE,prop=nonref
 100,I4,
**
** Prescribe unit particle acceleration a0 inwards,
** so that _volume_ acceleration is a0 * cross-section.
**  Distribute 1/4 to each corner node:   
*CLOAD
 LOADED_NODES,8,.25e-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