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Questions about Workbench environment

Questions about Workbench environment

Questions about Workbench environment

(OP)
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

RE: Questions about Workbench environment

Maheshh,
Specific questions like this one are nearly impossible to diagnose via message board.  I'd recommend you take the Ansys *.dsdb file for your analysis, zip it up, and put in on an FTP site.  If you did I (and i'm sure others) would be more than happy to see if we can help.

-Brian

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