×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

ABAQUS Error msg - Pls Guide..

ABAQUS Error msg - Pls Guide..

ABAQUS Error msg - Pls Guide..

(OP)
Hi All,

I am doing a simulation of Hip Bone Prosthesis.A brief introduction about this would be,I have a 3 D model of bone inside which a cavity is made(whose dimensions are in sink with implant which will be assembled inside it) and an implant has been assembled in abaqus.Now I need to run a simple static analysis on this.I have meshed both bone and implant using tetrahedron elements using free meshing technique since creating a mapped mesh for bone(irregular shape) will be difficult.I have created an interaction in initial step which generates contact between bone and implant,here I was not able to select complete cavity inside bone as it is not visible in view port.Boundary Conditions given in initial step and load in step 1.I got the below mentioned error msgs,after referring the documents in this forum I corrected certain details like,increasing steps,decreasing minimum/initial and maximum increment,still the below error persists,I need your help in this.I request you to give me some advice.

                                                                                      

     AUTOMATIC TIME CONTROL WITH -
          A SUGGESTED INITIAL TIME INCREMENT OF                 1.00    
          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    

     LINEAR EQUATION SOLVER TYPE         DIRECT SPARSE

 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    
     CRITERION FOR ZERO FORCE     REL. TO TIME AVRG. MAX. FORCE        1.000E-05
     CRITERION FOR ZERO DISP.    RELATIVE TO CHARACTERISTIC LENGTH     1.000E-08

     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    
     TIME INCREMENT INCREASE FACTOR BEFORE A TIME POINT                1.000    

 CONTACT CONTROLS APPLIED TO ALL CONTACT PAIRS:
     AUTOMATIC TOLERANCES FOR OVERCLOSURE AND SEPARATION
     PRESSURE ARE SUPPRESSED
     GLOBAL STABILIZATION CONTROL IS NOT USED
     FRICTION IS INCLUDED IN INCREMENT THAT THE CONTACT POINT CLOSES
     RELATIVE PENETRATION TOLERANCE FOR AUGMENTED LAGRANGE CONTACT:
          FINITE-SLIDING SURFACE-TO-SURFACE                            5.000E-02
          OTHERWISE                                                    1.000E-03

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

     THE MAXIMUM NUMBER OF INCREMENTS IN THIS STEP IS                     200

          LARGE DISPLACEMENT THEORY WILL BE USED

     LINEAR EXTRAPOLATION WILL BE USED

     CHARACTERISTIC ELEMENT LENGTH      2.37    

     DETAILED OUTPUT OF DIAGNOSTICS TO DATABASE REQUESTED

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

     EQUATIONS ARE BEING REORDERED TO MINIMIZE WAVEFRONT

 NUMBER OF CONTACT ELEMENTS WITHOUT NORMAL LM=     13649


     COLLECTING MODEL CONSTRAINT INFORMATION FOR OVERCONSTRAINT CHECKS

     COLLECTING STEP CONSTRAINT INFORMATION FOR OVERCONSTRAINT CHECKS

***WARNING: EXCESSIVE DISTORTION AT A TOTAL OF 28 INTEGRATION POINTS IN SOLID
             (CONTINUUM) ELEMENTS
 

 ***NOTE: ELEMENTS ARE DISTORTING EXCESSIVELY. CONVERGENCE IS JUDGED UNLIKELY.
 

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

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

***System matrix has so many negative eigenvalues values***

and abaqus aborts after these.

Pls guide....

RE: ABAQUS Error msg - Pls Guide..

- Check the boundary conditions to restrain rigid body motion

Quote:


AUTOMATIC TIME CONTROL WITH -
          A SUGGESTED INITIAL TIME INCREMENT OF                 1.00    
          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
The settings for automatic time incremetantion if you have contact should have smaller values:
you can try:
- initial time increment ~ 0.005
- mininimum ~1.e-15
- maximum  ~0.1
 
To select the inner geometric entities you have to use the Selection "Options" Toolbar when you are prompted to select a region. Using Selection Options you can restrict the selection to the inner entities.

For details see:
ABAQUS/CAE User's Manual -> 6.3 Using the selection options

If you have multiple parts instances you can use :
CAE->Main menu->View->Assembly Display Options->Instance Tab , to show/hide part instances.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close