Nonlinear analysis fails

[w_shibata]

When I run a nonlinear stress analysis on the model shown below, I get this message and the simulation fails.

The same message keeps appearing even after increasing the number of steps.

What should I do?

エラー: MAXIMUM NUMBER OF BISECTIONS PERMITTED REACHED
Cause : The bisection limit specified on the NLPARM (static solutions) or a TSTEPNL (transient
solutions) Bulk Data entry for the current load increment has been reached (default
5).
Action : Increase the bisection limit and/or investigate the reason for the load bisection.See
message E5075 above.

[henderh]

Hi @w_shibata,

For nonlinear static stress, the setup has to constrain bodies enough such that there are no open degrees of freedom that would allow rigid body movement (i.e. the attached setup is potentially a dynamic situation instead of static).

I believe the separation contacts are causing the solve to fail. The solve can complete successfully after changing the contact types to Bonded.

The Separation contacts allow Body2 to spin freely about the Z direction, and it can lift freely in the +Z direction:

If the goal is to analyze how much Body2 will move and Body1 deform, it could be beyond the capabilities of a static simulation solver.

I presume there will be friction, and stiction in real life. Separation contacts allow defining the coefficient of static friction, and an advanced option offers 'Frictional Stiffness For Stick'. Setting those in addition to constraining Body2 further may allow the solver a better chance to succeed.

The Autodesk Explicit solver used in the Dynamic Event Simulation study type can handle a similar setup using a very short time duration (1/1000th of a second). I set it up basically the same as the nonlinear static stress study, but took advantage of model symmetry. Also, the coefficient of friction value is set to 0.2 in the Separation contact settings (model attached):

I hope this helps. Please let us know if you have any additional questions, comments or suggestions.