Mechanica analysis run error with 'internal engine error'

[yzhu-2]

When I run a sensitivity design study, it occurs error at step 2, as rounded below in red spline. The design variable is tensile force. Why did it come out such a error?

This thread is inactive and closed by the PTC Community Management Team. If you would like to provide a reply and re-open this thread, please notify the moderator and reference the thread. You may also use "Start a topic" button to ask a new question. Please be sure to include what version of the PTC product you are using so another community member knowledgeable about your version may be able to assist.

[Chris3]

That is a general error that gets thrown out for a lot of issues. There is no one issue that causes that. Your best bet is to play a game of wack a mole. Try simplifying the geometry or eliminating boundary or load cases until it goes away. Then start to turn things (like contact interfaces) back one 1 by one until you get the message again. This will tell you what the problem is.

[yzhu-2]

I'm not exactly sure about your advise. I have tried many methods, but failed.

[Chris3]

Have you tried running the analysis with everything welded together (no free or contact interfaces)?

[yzhu-2]

If every part is weld together, there will be no this error, but it would not be in accord with the real contact situation.

[Chris3]

Right, so this helps narrow down the issue though. Do you have more than one interface? Try turning them back on one at a time until you get the failure. Once you get the failure you will know which one is causing the issue. At that point you can take a closer look at how you have defined that interface and or come up with an alternative way to define that interface.

[yzhu-2]

I want to know the difference of settings between bonded and contact with infinite friction?  Do they lead to the same effect?

[unickque]

The results will most certainly be different when the two parts are pulled away from each other

[yzhu-2]

As to my case, the two parts are connected wtih no distance, then what setting is suitable for it? And if pulled away, what difference will be to the results?

[unickque]

Bonded: the separate parts will act as if they were one part. They are bonded or 'glued' together. This means that if you pull the parts apart, the parts will not separate and you will get tensile stress.

Contact: if you pull the parts apart there will be separation and the stress will return to zero.

If your parts are in compressive contact (over the entire contact region! ) there will be no difference between bonding or contact with infinite friction.

The bonded assembly will however have much shorter calculation times, because no iteration is needed to reach an equilibrium in the contact zone.

[yzhu-2]

As to my case, there is friction at the contact surfaces. When applied tensile force as shown in figure, the cable tie will deform and generate relative silde between the contact surfaces. In Pro/e mechanica, it can only define the infinite friction in contact mode, which is not consistent with the real situation. How should I define the setting?

[unickque · Accepted solution]

In Creo 3 there is an option to define contact with finite friction. You can set a static and a dynamic coefficient of friction.

I haven't tried it, so can't help you any further with this.

[yzhu-2]

Thank you, very helpful!

[yzhu-2]

In the status log, the Von Mises Stress value is marked at or close to result singularity. Is the value still available as analysis reference?

[Chris3]

Bonding something and defining a contact region is not the same thing. Bonding something is like welding it together. There will be no localized stresses at the interface. When you define a contact interface Creo puts springs in between those surfaces. It then iteratively increases the stiffness of the springs until the loading is equalized. As the springs get stiffer, the local contact stress increases.

Here is a great presentation with some contact interface examples:

https://www.tu-chemnitz.de/mb/MHT/SAXSIM/2009/pdf/SAXSIM_2009_PTC_Jakel_The_Mechanica_Wildfire_4p0_Contact_with_Friction…

[yzhu-2]

Thank you very much! Only in PTC community can I find my desired answer.

[yzhu-2]

Sorry to trouble you. In the below two pictures, the cylinder is contacted to the arc surface at the boundary. Then should  I define the two surfaces as contact with infinite friction or contact without friction?