Thermal expansion of rubber seal

[mizzjoey]

Hi.

I've been trying to model a rubber seal undergoing thermal expansion between 2 rigids and a steel tube, from room temperature to 150C using Standard.

Model is axisymmetric and I'm using Marlow mat model. I ran one analysis with Al tube before and it ran well. For this analysis, all I did was change the mat and TE data of the tube to those of steel.

TE step of this analysis only ran about 80% of the total time. Msg file tells me that:
- a contact has failed to converge
- the severe discontinuity iterations are more than allowed
- time increment required is too small

Anyone can suggest how to overcome this? I've already relaxed the tolerance controls AND tried the stabilization parameter.

 

[mizzjoey]

Hi forum members.

I hope someone can answer another question I have regarding this project. I'm trying to use contact controls to solve the contact problems between the rubber seal and the steel tube.

Can anyone please brief me what the different options of contact controls do, and the different stabilization options in Standard as well?

I tried the *Static, stabilization in my step but it did not work.

Your help is much appreciated.

jo

 

[bassmanjax]

Hi

Have you tried reducing the minimum time increment in the *STATIC step?

Regards

Martin

 

[mizzjoey]

Thanks Martin.

I have, down to 1e-09. The analysis then kept stalling at 0.9 of total step time and I had to kill the job after some time.

I managed to make the job run by switching off the SDI in the step. Will this affect the accuracy of my solution? I'm not sure if I can use the results.

 

[Yoman228]

Did you use small sliding or finite sliding for the contact?

 

[mizzjoey]

Finite sliding, surf to surf contact.

I added a user-defined contact prop for the interaction as well, with a stabilization factor of 1E-6 and delayed friction offset.

The step cards are

** STEP: Step-2
**
*Step, name=Step-2, nlgeom=YES, inc=10000, convert sdi=NO
thermal expansion
*Static, stabilize=1e-06
0.1, 1., 1e-05, 1.
**
**
*CONTROLS, ANALYSIS=DISCONTINUOUS
**
** set displacement tolerance to 100%
**
*CONTROLS, PARAMETERS=FIELD, FIELD=DISPLACEMENT
,100.0