O-ring - simulation

[RansiDevendra6239]

Hi Everyone,

I am trying to simulate the behavior of an O-ring in its application. When I run the model it does not converge and terminates with an error. Can someone let me know why my model is not running properly? I have herewith attached the model and the results.

I look forward to hearing from you.

Thank you.

Best regards,

Ransi

[RansiDevendra6239]

Sorry, I herewith attached the .ach file.

Thank you.

Best regards,

Ransi

[John_Holtz]

Hi Ransi,

The analysis actually is converging (but slowly). The "Error File can not be deleted" is a random error that occurs when the Results environment is using the files while the analysis is running. The best solution that I have found (maybe the only solution?) is to run the analysis from a command prompt. You can periodically re-load the model into the Results environment to view the latest results, but otherwise keep the use of the Results environment to a minimum. See the article Simulation Mechanical: Error: " File can not be deleted. Error (1)" (I see one of the suggestions in the article is to turn off the "Automatic Advance" button. I still got the Error (1) when running your analysis from within the Sim Mech environment.)

I am not sure if it is the contact or the hyperelastic material (or both) that is causing the slow convergence. Here are some things that you could try:

• setting a contact stiffness=2000 lb/in and contact distance = 0.001 or 0.002 inch.
• using surface contact instead of sliding/no bounce. (I do not remember the theory of slide/no bounce, so I am not sure if it helps or not.
• Because you have a flat surface against a round surface, you could force the contact type to be point to surface (with the 0-ring being the secondary part in the contact definition.) Presumably the steel is much stiffer than the o-ring, so you can probably use a much coarser mesh on the steel parts. Both of these would reduce the number of contact elements.

[RansiDevendra6239]

Hi John,

Thank you for the advice.  However, I still find the same error message coming randomly and stopping the calculation?  When I checked the link (Autodesk)  it says possible fixes:

·         Clear the Simulation Job Manager temp folder

1.       Open “Autodesk Mechanical Simulation Job Manager.”

2.       Open Preferences

3.       Go to File Transfer tab

4.       Find the “File transfer temporary folder” location

5.       Go to the “File transfer temporary folder” of Step 4

6.       Delete all files in the “File transfer temporary folder”

When I checked I find the folders as shown in the attachment.  Can I delete all these folders?

Is there a method of completely overcoming this problem?

Please advise.

Thank you.

Best regards,

Ransi

[RansiDevendra6239]

Hi John,

When I use solver manager and resumed the analysis the analysis run more than the specified event duration.  Can you please explain this anomaly?

Thank you.

Best regards,

Ransi

[John_Holtz]

Hi Ransi,

Here are a number of answers to your questions.

Q1: Resume analysis anomaly? 

A1: Yes, it is a bug. Both "restart" and "resume" have problems when running the analysis from a command prompt, so I think the problem is in the solver and not in the interface.

Q2: Deleting the Sim Job Manager temporary folder.

A2: Yes, all of those folders can be deleted.

Q3: Any method to avoid the "File can not be deleted. Error (1)" problem?

A3. The only method that I know of that works is to not monitor the results while the analysis is running. You can close the Results environment if you are running the analysis from within the Sim Mech interface; this lets you view the solve log file as it scrolls in the output bar. Or you can free up RAM by exiting Sim Mech and running the analysis from a command prompt.

In theory, you can view the model in the Results environment and turn off the automatic monitoring ("Load Case Options > Automatic Advance" off and "Load Case Options > Analysis in Progress" off), but I have not had 100% success with this.