Convergence problems with soft material properties

[saja11]

Hi,
I have a knee joint model which needs to be simulated with Fibril reinforced poro elastic material properties. The model run fine with stiffer material properties but when i run the model with soft material properties (resembling human cartilage tissue), I can these convergence errors. Can someone suggest what I need to change in .inp file for this model? (I need to make changes in .inp file as I don't have access to .cae file)


Message file includes:

***WARNING: EXCESSIVE DISTORTION AT A TOTAL OF 2 INTEGRATION POINTS IN SOLID
(CONTINUUM) ELEMENTS


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

***ERROR: TIME INCREMENT REQUIRED IS LESS THAN THE MINIMUM SPECIFIED


***ERROR: TOO MANY ATTEMPTS MADE FOR THIS INCREMENT
ELEMENT PART2.9186 IS DISTORTING EXCESSIVELY.
ELEMENT PART2.9186 IS DISTORTING EXCESSIVELY.

***WARNING: EXCESSIVE DISTORTION AT A TOTAL OF 2 INTEGRATION POINTS IN SOLID
(CONTINUUM) ELEMENTS


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

***ERROR: THE ANALYSIS HAS BEEN TERMINATED DUE TO PREVIOUS ERRORS. OUTPUT FOR
THE LAST CONVERGED INCREMENT HAS NOT BEEN WRITTEN DUE TO CONVERGENCE
ISSUES.

 

[FEA way]

Locate this element (PART2.9186) in the output database and see how it behaves before the analysis stops. Maybe you will have to refine the mesh in this region or redefine boundary conditions/interactions.