Shrink fit + Inertial load

[4782]

Hai,

For quick understading: I simulating shrink fit between two cylinders and then i am applying inertia load to the model. I am facing convergence issue could any one can help me on this.

To be more clear, my shrink fit step solves perfectly , then i use the restart option in Ansys, to apply the inertia load (Acceleration) it solves for few substep and then the force convergence value keeps on increasing than the force criterion value. No other external forces were applied.

can anyone help me to solve this issue.

Thanks in advance

regards

Kan

 

[Stringmaker]

What type of contact have you used? Is it possible that the is not constrained axially right now and could be flying out of the hole?

 

[4782]

Hai,

I used standard 3D surface to surface contact, also i have specified the CNOF for the shrink fit.

For information, only the outer cylinder is constrained in all DOF.
I am thinking the shrink fit contact pressure developed in the first sub step should hold the inner cylider with the outer one when the inertia (Acceleration)loads are applied in axial direction in second load step. That is right now i don't have any contraint for the inner cylinder.

Please correct me if i am wrong.

kan

 

[Stringmaker]

Kan, try including friction to see if that holds it. I would try specifying the "rough" contact option. This is tough to diagnose via the internet but it sounds like the internal cylinder might be underconstrained in the axial direction. If this doesn't work make stop the analysis and look at load step 999999 to see why the model isn't converging. If you are running via GUI just hit the "Stop" button on the process dialog box. In batch mode create the file jobname.abt with the text "nonlinear" (no quotes and where jobname is your jobname of the analysis) in the first line of the text file. This will force Ansys to complete the current equilibrium iteration and write it to a result file. Diagnosing your problem should be straightforward from that point as you can view the displacements to see what's going on.

-Brian

 

[4782]

Brain,

Thanks and you are true. Although I have friction defined between the two cylinders it is not enough to hold them together when I apply the inertia load. With the slightly increased friction value now I could able to solve the problem with the inertia load in the axial direction.

But when I tried to solve for the lateral and vertical Inertial load with the shrink fit results and with the same friction value. I am facing the very very slow convergence in the moment but the convergence with the force in very quick. Very slow convergence in the moment is related to the new friction value !

kan