Dear Colleagues

I am a tyro of ABAQUS.   I would predict silo wall stress using ABAQUS. The
axisymmetrical elements (CAX8) are used to model the silo wall and bulked
solids. The interaction between silo wall and solids modelled using contact
element (INTER3A). The Cam-clay model is used to model the bulked
materials.  One error message shows that integration point in some element
have initial mean normal stress greater than or equal to 0.0. 
______________________________________________________________
1 ABAQUS VERSION 5.8-10       DATE 28-SEP-1999    TIME 11:33:31     PAGE    1
 FOR USE AT University of Wolverhampton UNDER ACADEMIC LICENSE FROM HKS,
INC.                                                    
 modified Cam-clay model-Axisymmetric simulation of squat steel silo
     
 self-grav load
     
 STEP    1     INCREMENT     1     STEP TIME   0.000E+00


                        S T E P       1     S T A T I C   A N A L Y S I S


          self-grav load
              

     AUTOMATIC TIME CONTROL WITH -
          A SUGGESTED INITIAL TIME INCREMENT OF                1.000E-02
          AND A TOTAL TIME PERIOD OF                            1.00    
          THE MINIMUM TIME INCREMENT ALLOWED IS                1.000E-05
          THE MAXIMUM TIME INCREMENT ALLOWED IS                 1.00    

 CONVERGENCE TOLERANCE PARAMETERS FOR FORCE    
     CRITERION FOR RESIDUAL FORCE     FOR A NONLINEAR PROBLEM
5.000E-03
     CRITERION FOR DISP.    CORRECTION IN A NONLINEAR PROBLEM
1.000E-02
     INITIAL VALUE OF TIME AVERAGE FORCE
1.000E-02
     AVERAGE FORCE     IS TIME AVERAGE FORCE    
     ALTERNATE CRIT. FOR RESIDUAL FORCE     FOR A NONLINEAR PROBLEM
2.000E-02
     CRITERION FOR ZERO FORCE     RELATIVE TO TIME AVRG. FORCE
1.000E-05
     CRITERION FOR RESIDUAL FORCE     WHEN THERE IS ZERO FLUX
1.000E-05
     CRITERION FOR DISP.    CORRECTION WHEN THERE IS ZERO FLUX
1.000E-03
     CRITERION FOR RESIDUAL FORCE     FOR A LINEAR INCREMENT
1.000E-08
     FIELD CONVERSION RATIO
1.00    

     VOLUMETRIC STRAIN COMPATIBILITY TOLERANCE FOR HYBRID SOLIDS
1.000E-05
     AXIAL STRAIN COMPATIBILITY TOLERANCE FOR HYBRID BEAMS
1.000E-05
     TRANS. SHEAR STRAIN COMPATIBILITY TOLERANCE FOR HYBRID BEAMS
1.000E-05
     SOFT CONTACT CONSTRAINT COMPATIBILITY TOLERANCE FOR P>P0
5.000E-03
     SOFT CONTACT CONSTRAINT COMPATIBILITY TOLERANCE FOR P=0.0
0.100    
     DISPLACEMENT COMPATIBILITY TOLERANCE FOR DCOUP ELEMENTS
1.000E-05
     ROTATION COMPATIBILITY TOLERANCE FOR DCOUP ELEMENTS
1.000E-05

 TIME INCREMENTATION CONTROL PARAMETERS:
     FIRST EQUILIBRIUM ITERATION FOR CONSECUTIVE DIVERGENCE CHECK
   4
     EQUILIBRIUM ITERATION AT WHICH LOG. CONVERGENCE RATE CHECK BEGINS
   8
     EQUILIBRIUM ITERATION AFTER WHICH ALTERNATE RESIDUAL IS USED
   9
     MAXIMUM EQUILIBRIUM ITERATIONS ALLOWED
  16
     EQUILIBRIUM ITERATION COUNT FOR CUT-BACK IN NEXT INCREMENT
  10
     MAXIMUM EQUILIB. ITERS IN TWO INCREMENTS FOR TIME INCREMENT INCREASE
   4
     MAXIMUM ITERATIONS FOR SEVERE DISCONTINUITIES
  12
     MAXIMUM CUT-BACKS ALLOWED IN AN INCREMENT
   5
     MAXIMUM DISCON. ITERS IN TWO INCREMENTS FOR TIME INCREMENT INCREASE
   6
     CUT-BACK FACTOR AFTER DIVERGENCE
0.2500    
     CUT-BACK FACTOR FOR TOO SLOW CONVERGENCE
0.5000    
     CUT-BACK FACTOR AFTER TOO MANY EQUILIBRIUM ITERATIONS
0.7500    
     CUT-BACK FACTOR AFTER TOO MANY SEVERE DISCONTINUITY ITERATIONS
0.2500    
     CUT-BACK FACTOR AFTER PROBLEMS IN ELEMENT ASSEMBLY
0.2500    
     INCREASE FACTOR AFTER TWO INCREMENTS THAT CONVERGE QUICKLY
1.500    
     MAX. TIME INCREMENT INCREASE FACTOR ALLOWED
1.500    
     MAX. TIME INCREMENT INCREASE FACTOR ALLOWED (DYNAMICS)
1.250    
     MAX. TIME INCREMENT INCREASE FACTOR ALLOWED (DIFFUSION)
2.000    
     MINIMUM TIME INCREMENT RATIO FOR EXTRAPOLATION TO OCCUR
0.1000    
     MAX. RATIO OF TIME INCREMENT TO STABILITY LIMIT
1.000    
     FRACTION OF STABILITY LIMIT FOR NEW TIME INCREMENT
0.9500    

          PRINT OF INCREMENT NUMBER, TIME, ETC., EVERY    1  INCREMENTS

     RESTART FILE WILL BE WRITTEN EVERY   999  INCREMENTS

     THE MAXIMUM NUMBER OF INCREMENTS IN THIS STEP IS                      10

          UNSYMMETRIC MATRIX STORAGE AND SOLUTION WILL BE USED

     EXTRAPOLATION WILL BE USED

     CHARACTERISTIC ELEMENT LENGTH     0.974    

     PRINT OF INCREMENT NUMBER, TIME, ETC., TO THE MESSAGE FILE EVERY     1
 INCREMENTS

 ***ERROR: ELEMENT 702 INTEGRATION POINT 1 HAS AN INITIAL MEAN NORMAL STRESS 
           GREATER THAN OR EQUAL TO 0.0



     ANALYSIS SUMMARY:
     TOTAL OF          0  INCREMENTS
                       0  CUTBACKS IN AUTOMATIC INCREMENTATION
                       0  ITERATIONS
                       0  PASSES THROUGH THE EQUATION SOLVER OF WHICH 
                       0  INVOLVE MATRIX DECOMPOSITION, INCLUDING
                       0  DECOMPOSITION(S) OF THE MASS MATRIX
                       0  ADDITIONAL RESIDUAL EVALUATIONS FOR LINE SEARCHES
                       0  ADDITIONAL OPERATOR EVALUATIONS FOR LINE SEARCHES
                       7  WARNING MESSAGES DURING USER INPUT PROCESSING
                       0  WARNING MESSAGES DURING ANALYSIS
                       0  ANALYSIS WARNINGS ARE NUMERICAL PROBLEM MESSAGES
                       0  ANALYSIS WARNINGS ARE NEGATIVE EIGENVALUE MESSAGES
                       1  ERROR MESSAGES


     THE SPARSE SOLVER HAS BEEN USED FOR THIS ANALYSIS.



     JOB TIME SUMMARY
       USER TIME (SEC)      =  5.00000E-02
       SYSTEM TIME (SEC)    =  9.00000E-02
       TOTAL CPU TIME (SEC) =  0.14000    
       WALLCLOCK TIME (SEC) =          0
______________________________________________

I am grateful to get any insight from FEM colleagues. 

Many thanks.

Shenkai



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