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Abaqus convergence issue with *Controls

Abaqus convergence issue with *Controls

Abaqus convergence issue with *Controls

(OP)
Hello,

I am running the previous Abaqus model with changed loading magnitudes. Up to steps 8 my analysis can't converge. I have tried to use *controls to adjust the convergence criteria. But I am not familiar with it. I got the warning and error messages saying too many attempts. My input step and the corresponding message is as follow. Please anyone can advise how do I tune the magnitude in the *controls? Many thanks.

**-----------------------------------------------------------------------------------------------------------------------
**STEP 8 - WATERFILL
**The pipeline is filled with fresh water for the pressure test with mass density equal to 1000kg/m3.
**With a free surface at z = 0, this will also give an internal pressure equal to 1000·9.81·372Pa = 36.5bar.
**------------------------------------------------------------------------------------------------------------------------
*STEP, NAME=Waterfill, NLGEOM, INC=2000
*STATIC, STABILIZE, FACTOR=10
** dt_start t_end dt_min dt_max
0.00001, 1.0, 1.00E-10, 0.4
*CONTROLS, PARAMETERS=FIELD
1.0, 100.0, , 200.0
*CONTROLS, PARAMETERS=TIME INCREMENTATION
** Increase load incrementation faster than default
, , , , , , , , ,
, , , , , ,2,
,2, , , , , ,
**
*DLOAD
** Elements Bouyancy Scaling OD_eff Dens_int ID_eff Surf_int
PIPE_SEGMENT_ALL, PB, 1.0, 0.488, 1000, 0.314, 0.00
**
*RESTART, WRITE, FREQUENCY=99999
*OUTPUT, FIELD, VARIABLE=ALL, FREQUENCY=99999
*END STEP

S T E P 8 S T A T I C A N A L Y S I S




AUTOMATIC TIME CONTROL WITH -
A SUGGESTED INITIAL TIME INCREMENT OF 1.000E-05
AND A TOTAL TIME PERIOD OF 1.00
THE MINIMUM TIME INCREMENT ALLOWED IS 1.000E-10
THE MAXIMUM TIME INCREMENT ALLOWED IS 0.400

LINEAR EQUATION SOLVER TYPE DIRECT SPARSE

AUTOMATIC STABILIZATION WITH DAMPING FACTOR = 10.0

CONVERGENCE TOLERANCE PARAMETERS FOR FORCE
*** CRITERION FOR RESIDUAL FORCE FOR A NONLINEAR PROBLEM 1.00
*** CRITERION FOR DISP. CORRECTION IN A NONLINEAR PROBLEM 100.
*** USER DEFINED VALUE OF AVERAGE FORCE NORM 200.
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
CRITERION FOR ZERO FORCE REL. TO TIME AVRG. MAX. FORCE 1.000E-05
CRITERION FOR ZERO DISP. RELATIVE TO CHARACTERISTIC LENGTH 1.000E-08

CONVERGENCE TOLERANCE PARAMETERS FOR MOMENT
*** CRITERION FOR RESIDUAL MOMENT FOR A NONLINEAR PROBLEM 1.00
*** CRITERION FOR ROTATION CORRECTION IN A NONLINEAR PROBLEM 100.
*** USER DEFINED VALUE OF AVERAGE MOMENT NORM 200.
ALTERNATE CRIT. FOR RESIDUAL MOMENT FOR A NONLINEAR PROBLEM 2.000E-02
CRITERION FOR ZERO MOMENT RELATIVE TO TIME AVRG. MOMENT 1.000E-05
CRITERION FOR RESIDUAL MOMENT WHEN THERE IS ZERO FLUX 1.000E-05
CRITERION FOR ROTATION CORRECTION WHEN THERE IS ZERO FLUX 1.000E-03
CRITERION FOR RESIDUAL MOMENT FOR A LINEAR INCREMENT 1.000E-08
FIELD CONVERSION RATIO 1.00
CRITERION FOR ZERO MOMENT REL. TO TIME AVRG. MAX. MOMENT 1.000E-05

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
CONTACT FORCE ERROR TOLERANCE FOR CONVERT SDI=YES 1.00
DISPLACEMENT COMPATIBILITY TOLERANCE FOR DCOUP ELEMENTS 1.000E-05
ROTATION COMPATIBILITY TOLERANCE FOR DCOUP ELEMENTS 1.000E-05

*** INDICATES USE OF NON-DEFAULT CONVERGENCE TOLERANCE PARAMETER
SELECTED WITH *CONTROLS

EQUILIBRIUM WILL BE CHECKED FOR SEVERE DISCONTINUITY ITERATIONS

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 50
MAXIMUM CUT-BACKS ALLOWED IN AN INCREMENT 5
MAXIMUM DISCON. ITERS IN TWO INCREMENTS FOR TIME INCREMENT INCREASE 50
MAXIMUM CONTACT AUGMENTATIONS FOR *SURFACE BEHAVIOR,AUGMENTED LAGRANGE 50
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 2.000
*** MAX. TIME INCREMENT INCREASE FACTOR ALLOWED 2.000
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
TIME INCREMENT INCREASE FACTOR BEFORE A TIME POINT 1.000

*** INDICATES USE OF NON-DEFAULT TIME INCREMENTATION CONTROL PARAMETER
SELECTED WITH *CONTROLS
GLOBAL STABILIZATION CONTROL IS NOT USED

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

RESTART FILE WILL BE WRITTEN EVERY 99999 INCREMENTS

THE MAXIMUM NUMBER OF INCREMENTS IN THIS STEP IS 2000

LARGE DISPLACEMENT THEORY WILL BE USED

UNSYMMETRIC MATRIX STORAGE AND SOLUTION WILL BE USED

LINEAR EXTRAPOLATION WILL BE USED

CHARACTERISTIC ELEMENT LENGTH 1.00

DETAILS REGARDING ACTUAL SOLUTION WAVEFRONT REQUESTED

DETAILED OUTPUT OF DIAGNOSTICS TO DATABASE REQUESTED

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

COLLECTING STEP CONSTRAINT INFORMATION FOR OVERCONSTRAINT CHECKS


INCREMENT 1 STARTS. ATTEMPT NUMBER 1, TIME INCREMENT 1.000E-05

***WARNING: THERE ARE 4003 UNCONNECTED REGIONS IN THE MODEL.

NUMBER OF EQUATIONS = 40013 NUMBER OF FLOATING PT. OPERATIONS = 4.01E+07

CHECK POINT START OF SOLVER

CHECK POINT END OF SOLVER

ELAPSED USER TIME (SEC) = 0.50000
ELAPSED SYSTEM TIME (SEC) = 0.10000
ELAPSED TOTAL CPU TIME (SEC) = 0.60000
ELAPSED WALLCLOCK TIME (SEC) = 1


***WARNING: THE SYSTEM MATRIX HAS 8827 NEGATIVE EIGENVALUES.
EXPLANATIONS ARE SUGGESTED AFTER THE FIRST OCCURRENCE OF THIS MESSAGE.

***WARNING: THE PLASTICITY/CREEP/CONNECTOR FRICTION ALGORITHM DID NOT CONVERGE
AT 32000 POINTS


***NOTE: MATERIAL CALCULATIONS FAILED TO CONVERGE OR WERE NOT ATTEMPTED AT ONE
OR MORE POINTS. CONVERGENCE IS JUDGED UNLIKELY.


INCREMENT 1 STARTS. ATTEMPT NUMBER 2, TIME INCREMENT 2.500E-06

NUMBER OF EQUATIONS = 40013 NUMBER OF FLOATING PT. OPERATIONS = 4.01E+07

CHECK POINT START OF SOLVER

CHECK POINT END OF SOLVER

ELAPSED USER TIME (SEC) = 0.40000
ELAPSED SYSTEM TIME (SEC) = 0.10000
ELAPSED TOTAL CPU TIME (SEC) = 0.50000
ELAPSED WALLCLOCK TIME (SEC) = 0


***WARNING: THE SYSTEM MATRIX HAS 8854 NEGATIVE EIGENVALUES.
EXPLANATIONS ARE SUGGESTED AFTER THE FIRST OCCURRENCE OF THIS MESSAGE.

***WARNING: THE PLASTICITY/CREEP/CONNECTOR FRICTION ALGORITHM DID NOT CONVERGE
AT 32000 POINTS


***NOTE: MATERIAL CALCULATIONS FAILED TO CONVERGE OR WERE NOT ATTEMPTED AT ONE
OR MORE POINTS. CONVERGENCE IS JUDGED UNLIKELY.


INCREMENT 1 STARTS. ATTEMPT NUMBER 3, TIME INCREMENT 6.250E-07

NUMBER OF EQUATIONS = 40013 NUMBER OF FLOATING PT. OPERATIONS = 4.01E+07

CHECK POINT START OF SOLVER

CHECK POINT END OF SOLVER

ELAPSED USER TIME (SEC) = 0.50000
ELAPSED SYSTEM TIME (SEC) = 0.0000
ELAPSED TOTAL CPU TIME (SEC) = 0.50000
ELAPSED WALLCLOCK TIME (SEC) = 1


***WARNING: THE SYSTEM MATRIX HAS 8579 NEGATIVE EIGENVALUES.
EXPLANATIONS ARE SUGGESTED AFTER THE FIRST OCCURRENCE OF THIS MESSAGE.

***WARNING: THE PLASTICITY/CREEP/CONNECTOR FRICTION ALGORITHM DID NOT CONVERGE
AT 32000 POINTS


***NOTE: MATERIAL CALCULATIONS FAILED TO CONVERGE OR WERE NOT ATTEMPTED AT ONE
OR MORE POINTS. CONVERGENCE IS JUDGED UNLIKELY.


INCREMENT 1 STARTS. ATTEMPT NUMBER 4, TIME INCREMENT 1.563E-07

NUMBER OF EQUATIONS = 40013 NUMBER OF FLOATING PT. OPERATIONS = 4.01E+07

CHECK POINT START OF SOLVER

CHECK POINT END OF SOLVER

ELAPSED USER TIME (SEC) = 0.30000
ELAPSED SYSTEM TIME (SEC) = 0.10000
ELAPSED TOTAL CPU TIME (SEC) = 0.40000
ELAPSED WALLCLOCK TIME (SEC) = 0


***WARNING: THE SYSTEM MATRIX HAS 8028 NEGATIVE EIGENVALUES.
EXPLANATIONS ARE SUGGESTED AFTER THE FIRST OCCURRENCE OF THIS MESSAGE.

***WARNING: THE PLASTICITY/CREEP/CONNECTOR FRICTION ALGORITHM DID NOT CONVERGE
AT 32000 POINTS


***NOTE: MATERIAL CALCULATIONS FAILED TO CONVERGE OR WERE NOT ATTEMPTED AT ONE
OR MORE POINTS. CONVERGENCE IS JUDGED UNLIKELY.


INCREMENT 1 STARTS. ATTEMPT NUMBER 5, TIME INCREMENT 3.906E-08

NUMBER OF EQUATIONS = 40013 NUMBER OF FLOATING PT. OPERATIONS = 4.01E+07

CHECK POINT START OF SOLVER

CHECK POINT END OF SOLVER

ELAPSED USER TIME (SEC) = 0.40000
ELAPSED SYSTEM TIME (SEC) = 0.0000
ELAPSED TOTAL CPU TIME (SEC) = 0.40000
ELAPSED WALLCLOCK TIME (SEC) = 0


***WARNING: THE SYSTEM MATRIX HAS 7718 NEGATIVE EIGENVALUES.
EXPLANATIONS ARE SUGGESTED AFTER THE FIRST OCCURRENCE OF THIS MESSAGE.

***WARNING: THE PLASTICITY/CREEP/CONNECTOR FRICTION ALGORITHM DID NOT CONVERGE
AT 32000 POINTS


***NOTE: MATERIAL CALCULATIONS FAILED TO CONVERGE OR WERE NOT ATTEMPTED AT ONE
OR MORE POINTS. CONVERGENCE IS JUDGED UNLIKELY.


***ERROR: TOO MANY ATTEMPTS MADE FOR THIS INCREMENT

RE: Abaqus convergence issue with *Controls

maybe you start with a even smaller time increment and have decrease the minimum increment say

1e-10, 1.0, 1.00E-20, ,
or 1e-20, 1.0, 1.00e-25, ,

it worked once for me with a very small loading size.

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