I have been trying to solve a complex contact problem in workbench environment for a while now. I have following questions:
1) In the geometry branch of the tree all the 4 items have a small check mark at the side before the analysis begins. Then once I try to solve it, then I get this message:
Error: The solver engine was unable to converge on a solution for the nonlinear problem as constrained. Please see the Troubleshooting section of the Help System for more information. Project>Model>Environment>Solution 5/1/2007 1:53:18 PM
And then all the check marks next to the items in the geometry are crossed out. As if something is wrong.
2) I have been trying to following the settings suggested by "cbrn". But no luck.
LOAD STEP NUMBER. . . . . . . . . . . . . . . . 1
TIME AT END OF THE LOAD STEP. . . . . . . . . . 1.0000
AUTOMATIC TIME STEPPING . . . . . . . . . . . . ON
INITIAL NUMBER OF SUBSTEPS . . . . . . . . . 100
MAXIMUM NUMBER OF SUBSTEPS . . . . . . . . . 100
MINIMUM NUMBER OF SUBSTEPS . . . . . . . . . 10
MAXIMUM NUMBER OF EQUILIBRIUM ITERATIONS. . . . 100
STEP CHANGE BOUNDARY CONDITIONS . . . . . . . . NO
STRESS-STIFFENING . . . . . . . . . . . . . . . ON
TERMINATE ANALYSIS IF NOT CONVERGED . . . . . .YES (EXIT)
CONVERGENCE CONTROLS. . . . . . . . . . . . . .USE DEFAULTS
PRINT OUTPUT CONTROLS . . . . . . . . . . . . .NO PRINTOUT
PROBLEM DIMENSIONALITY. . . . . . . . . . . . .3-D
DEGREES OF FREEDOM. . . . . . UX UY UZ ROTX ROTY ROTZ
ANALYSIS TYPE . . . . . . . . . . . . . . . . .STATIC (STEADY-STATE)
NONLINEAR GEOMETRIC EFFECTS . . . . . . . . . .ON
EQUATION SOLVER OPTION. . . . . . . . . . . . .SPARSE
NEWTON-RAPHSON OPTION . . . . . . . . . . . . .PROGRAM CHOSEN
GLOBALLY ASSEMBLED MATRIX . . . . . . . . . . .SYMMETRIC
I thought that if I have 100 substeps, then the load of 50N will be ramped over the substeps. But it does not seem so. I think it is applied immediately and hence there are problems. Over the 100 substeps:
Subtstep 1 = 0 N
Substep 2 through Substep 100 = 50 N
How can I change this?
3) I have two moving parts which are hinged. I have defined a revolute contact. And this is my first time. Following warnings are hard for me to understand:
*** WARNING *** CP = 6.312 TIME= 13:53:00
Pivoting option activated for Sparse Direct Solver. The memory
required may greatly exceed predicted amount. In that event rerun
with increased memory using -m option (refer to the Basic Analysis
Procedures Guide, Ch. 19).
Sparse solver maximum pivot= 1.55586574E+19 at node 8605 UZ.
Sparse solver minimum pivot= -9.4805742E+19 at node 11161 UX.
Sparse solver minimum pivot in absolute value= 1.336904631E-08 at node
19508 ROTZ.
EQUIL ITER 1 COMPLETED. NEW TRIANG MATRIX. MAX DOF INC= -0.2188E+05
LINE SEARCH PARAMETER = 0.5000E-01 SCALED MAX DOF INC = -1094.
1 JOINT ELEMENTS WITH LAG MULT OPTION DO NOT SATISFY JOINT CONSTRAINT CONDITIONS
FORCE CONVERGENCE VALUE = 0.1418E+14 CRITERION= 0.1158
EQUIL ITER 2 COMPLETED. NEW TRIANG MATRIX. MAX DOF INC= 289.8
4) Eventually I get this error:
*** ERROR *** CP = 24.641 TIME= 13:53:17
One or more elements have become highly distorted. Excessive
distortion of elements is usually a symptom indicating the need for
corrective action elsewhere. Try incrementing the load more slowly
(increase the number of substeps or decrease the time step size). You
may need to improve your mesh to obtain elements with better aspect
ratios. Also consider the behavior of materials, contact pairs,
and/or constraint equations. If this message appears in the first
iteration of first substep, be sure to perform element shape checking.
Any help would be appreciated.
Thanks,
Mahesh
1) In the geometry branch of the tree all the 4 items have a small check mark at the side before the analysis begins. Then once I try to solve it, then I get this message:
Error: The solver engine was unable to converge on a solution for the nonlinear problem as constrained. Please see the Troubleshooting section of the Help System for more information. Project>Model>Environment>Solution 5/1/2007 1:53:18 PM
And then all the check marks next to the items in the geometry are crossed out. As if something is wrong.
2) I have been trying to following the settings suggested by "cbrn". But no luck.
LOAD STEP NUMBER. . . . . . . . . . . . . . . . 1
TIME AT END OF THE LOAD STEP. . . . . . . . . . 1.0000
AUTOMATIC TIME STEPPING . . . . . . . . . . . . ON
INITIAL NUMBER OF SUBSTEPS . . . . . . . . . 100
MAXIMUM NUMBER OF SUBSTEPS . . . . . . . . . 100
MINIMUM NUMBER OF SUBSTEPS . . . . . . . . . 10
MAXIMUM NUMBER OF EQUILIBRIUM ITERATIONS. . . . 100
STEP CHANGE BOUNDARY CONDITIONS . . . . . . . . NO
STRESS-STIFFENING . . . . . . . . . . . . . . . ON
TERMINATE ANALYSIS IF NOT CONVERGED . . . . . .YES (EXIT)
CONVERGENCE CONTROLS. . . . . . . . . . . . . .USE DEFAULTS
PRINT OUTPUT CONTROLS . . . . . . . . . . . . .NO PRINTOUT
PROBLEM DIMENSIONALITY. . . . . . . . . . . . .3-D
DEGREES OF FREEDOM. . . . . . UX UY UZ ROTX ROTY ROTZ
ANALYSIS TYPE . . . . . . . . . . . . . . . . .STATIC (STEADY-STATE)
NONLINEAR GEOMETRIC EFFECTS . . . . . . . . . .ON
EQUATION SOLVER OPTION. . . . . . . . . . . . .SPARSE
NEWTON-RAPHSON OPTION . . . . . . . . . . . . .PROGRAM CHOSEN
GLOBALLY ASSEMBLED MATRIX . . . . . . . . . . .SYMMETRIC
I thought that if I have 100 substeps, then the load of 50N will be ramped over the substeps. But it does not seem so. I think it is applied immediately and hence there are problems. Over the 100 substeps:
Subtstep 1 = 0 N
Substep 2 through Substep 100 = 50 N
How can I change this?
3) I have two moving parts which are hinged. I have defined a revolute contact. And this is my first time. Following warnings are hard for me to understand:
*** WARNING *** CP = 6.312 TIME= 13:53:00
Pivoting option activated for Sparse Direct Solver. The memory
required may greatly exceed predicted amount. In that event rerun
with increased memory using -m option (refer to the Basic Analysis
Procedures Guide, Ch. 19).
Sparse solver maximum pivot= 1.55586574E+19 at node 8605 UZ.
Sparse solver minimum pivot= -9.4805742E+19 at node 11161 UX.
Sparse solver minimum pivot in absolute value= 1.336904631E-08 at node
19508 ROTZ.
EQUIL ITER 1 COMPLETED. NEW TRIANG MATRIX. MAX DOF INC= -0.2188E+05
LINE SEARCH PARAMETER = 0.5000E-01 SCALED MAX DOF INC = -1094.
1 JOINT ELEMENTS WITH LAG MULT OPTION DO NOT SATISFY JOINT CONSTRAINT CONDITIONS
FORCE CONVERGENCE VALUE = 0.1418E+14 CRITERION= 0.1158
EQUIL ITER 2 COMPLETED. NEW TRIANG MATRIX. MAX DOF INC= 289.8
4) Eventually I get this error:
*** ERROR *** CP = 24.641 TIME= 13:53:17
One or more elements have become highly distorted. Excessive
distortion of elements is usually a symptom indicating the need for
corrective action elsewhere. Try incrementing the load more slowly
(increase the number of substeps or decrease the time step size). You
may need to improve your mesh to obtain elements with better aspect
ratios. Also consider the behavior of materials, contact pairs,
and/or constraint equations. If this message appears in the first
iteration of first substep, be sure to perform element shape checking.
Any help would be appreciated.
Thanks,
Mahesh
