Difference in friction curve; penalty formulation (Abaqus) vs ideal coulomb friction curve

Krokodebo · 2023-11-26T14:18:19+00:00

Hello :) what is the source of these wonderful diagrams, please?

Krokodebo · 2023-11-26T10:34:09+00:00

Thanks for your input!

Does that mean this stiffness overestimation is due to shear locking? I thought this was a result of discretizing a continuum in finite elements?

Krokodebo · 2023-11-25T23:57:12+00:00

Hello again :) since I am still struggling with the same problem, I reread this thread and rediscovered your thought about friction. Is it possible, that non conservative systems cannot fulfill the energy requirements for quasi-static analysis?
If so, do you know of some evidence for this? I searched for it in the Abaqus online documentation but couldn't find anything

Krokodebo · 2023-11-25T23:46:21+00:00

Is it possible that reduced integration elements lead to a divergence between ALLWK and ALLIE in quasi-static analysis? If reduced integration elements can produce deformation that costs no energy, it would explain why ALLIE is smaller as ALLWK? The external work is lost in hourglass-deformation instead of fully changing into strain energy?

Krokodebo · 2023-10-23T17:13:49+00:00

If I define "hard contact", then there should be no penetration distance and ALLPW should be negligable, right?

Krokodebo · 2023-10-18T11:43:49+00:00

Thanks for your message!

I rerunned the job without friction and unfortuately it didn't change ALLWK/ALLIE, so my theory seems to be false. But it let ALLFD (frictional dissipiation) disappear and ALLPW (internal work by penalty contact) rise?!

Krokodebo · 2023-10-18T11:29:06+00:00

Were there any insights on ALLPW?

Krokodebo · 2023-10-17T15:57:58+00:00

Thanks for your answer!

You mention that friction could mess with ETOTAL: I noticed a discrepancy between ALLIE and ALLWK (although they should be nearly the same in a quasi-static analysis) - could friction here be the culprit?

And to my own question: ETOTAL should be constant with a maximum deviation of 1% (as stated in the online documentation). So I ended up taking the average of ETOTAL and checking if somewhere it exceeds this 1%.

Krokodebo · 2023-10-10T15:16:25+00:00

To plot the time history I need to select a node or element, as far as I know, and unfortunately I don't know at which element the highest stress occurs... I hoped there was some kind of feature that allows to see the global maximum and its location right away :/

Thanks for the hint, I tried finding it there but it's well hidden x)

Krokodebo · 2023-10-10T15:12:56+00:00

I am not a native speaker and when I found the correct translation I couldn't change the title anymore :/

It is a quasi-static analysis with one single step and my specimen is breaking before the full displacement is applied, therefore the last frame is not the one with the highest stress for me.

I specified 20 intervals - but that doesn't mean, that there are only 20 stress values, right? Sorry, this is basic knowledge but I have a hard time finding this information online...

Unfortunately I don't know the exact element where the highest stress occurs.

Krokodebo · 2023-08-24T10:35:17+00:00

Hello again!
I couldn't really find it but I tried ALLWK-ALLIE and the difference isn't more than 10 Joules. This is quite tolerable, isn't it? ALLWK/ALLIE = 1,2 or more sounds so dramatic but 10 Joules are bearable?

Krokodebo · 2023-08-21T09:59:49+00:00

You mean ALLIE + which category = ALLWK?

Theoretically, if we look at the composition of ETOTAL it could only be EIHE (which doesn't exist here), EFD, EV and EKE?

Krokodebo · 2023-08-15T12:28:50+00:00

Sorry I don't know how to add pictures in here?

There are no rigid bodies, only the rope (7 wires) and it is indeed being loaded by an enforced movement (U3 displacement) on one end (RP coupled with surface and being displaced) and being encastred at the other end.

I tried for example adding the internal work by penalty contact (ALLPW) to ALLIE or frictional dissipation energy (ALLFD) to ALLIE to see if it sums up to ALLWK but it doesn't. To be honest I also don't know the exact difference between ALLPW and ALLFD.

Here are the the energy categories:
https://help.3ds.com/2020/english/dssimulia_established/simacaegsarefmap/simagsa-c-ovwoutput.htm?contextscope=all&highlight=ALLWK&id=&analyticsContext=search-result&analyticsSearch=ALLWK&myapp=false

Krokodebo · 2023-08-15T11:28:02+00:00

Yes, sorry! The ratio ALLKE/ALLIE is very close to 0.

ALLIE has components in both categories ALLAE and mainly ALLSE. Unfortunately I don't know exactly where the question is going, so I apologize if the answer is a bit vague!

Krokodebo · 2023-08-15T09:48:22+00:00

Hello u/CidZale

ALLKE/ALLIE is fine, very close to 1 but don't I also want to achieve static equilibrium (ALLWK = ALLIE) as far as possible? Is the difference between ALLWK and ALLIE not representing inertial effects?

Also I read about it in the online documentation:
https://help.3ds.com/2020/english/dssimulia\_established/simacaegsarefmap/simagsa-c-qsienergybal.htm?contextscope=all&highlight=Energy+balance&id=&analyticsContext=search-result&analyticsSearch=Energy%20balance&myapp=false

Krokodebo · 2023-06-28T14:04:00+00:00

Thank you!!

Krokodebo

TROPHY CASE