Meaning of warning message on job monitor?

[ShadowWarrior]

Hi all, I am seeing these warning messages on job monitor. Can anybody explain why these warnings are showing?

Basically, there are 3 warnings -
1. OP=NEW on *CONTACT is ignored when the general contact definition is specified as model data.
Background- The model has both general contact and self contact defined.
2. There are 1 warning messages in the data (.dat) file. Please check the data file for possible errors in the input file.
TYPE=BELOW MIN mass scaling will be ignored for mass elements.
TYPE=BELOW MIN mass scaling will be ignored for rigid elements.
Background- The model has rigid plate dropping on a deformable body. I have used variable mass scaling with below min option (specified target stable time increment).
3. The elements in the element set WarnElemSurfaceIntersect-Step1 are involved in surface intersections. Refer to the status and message file for further details.

 

[msjoey]

Hi,

I'm curious (and not likely to be able to offer a solution, sorry)... did your analysis run? Based on the warning messages I presume that it did, and Abaqus was simply telling you mass scaling was applied on 2D & 3D elements but not 0D (point mass) and rigids.

cheers
Jo

 

[ShadowWarrior]

Yes it ran fine and the result was good too. That is why I was wondering why showing warnings then. Thanks buddy!

Do you have any idea about No. 1 and 3 warning?

 

[msjoey]

Sometimes Abaqus shows warnings if it detects redundant keywords in the input file. But a warning may or may not lead to a fatal error (for fatal errors Abaqus will terminate).

My guess is, for #1: you may have specified general contact, and after that added another contact for specific area. Abaqus may be telling you that the second one is unnecessary therefore the second contact was ignored during the analysis. Just for you to be aware, as the analyst, in case your results seemed off you'll know where to start checking.

#3: you might want to check if some nodes / elems were overlapping at t=0 (beginning of analysis). This happens to me when I work with shell and beams. Because I forget to switch on 3D visualization I'm unaware that shell thickness or beam section might be in each other's way.

Basically warnings are things that Abaqus wants you to know, that might affect accuracy of your results.

Hope this helps,
Jo

 

[ShadowWarrior]

Hi msjoey, You are right about both warnings.

#1 - I have defined General contact for the whole of a 3 part model, top rigid plate + deforming body + bottom rigid plate. Then defined self contact for the deforming body only. Does the warning mean the self contact is not working?

#2 - Yes, the bottom rigid plate (zero thickness) is touching the deforming body at the bottom, but there should not be any intersecting contact. How do I overcome this?

 

[msjoey]

Hi,

I'm not an expert but these are my best guesses...

1- As far as I know Abaqus computes general contact differently than self contact. Therefore if you have self contact + general contact in your model Abaqus will carry out the analysis with both contact definitions active. But if you define general contact + contact pair, the contact pair is redundant and will be ignored. See this PDF; it's quite good and comprehensive

http://marketing.intrinsys.co.uk/CONTACT_SEMINAR.pdf

2- Can you post a screen cap of this intersecting contact? I'm having trouble imagining the analysis setup. This week I'm working with discrete rigid plate crushing a vehicle structure... we may have similar contact issues.

cheers
Jo

 

[ShadowWarrior]

Hi

I removed General contact and defined 2 contact pair for "top rigid plate-to-deforming body" and "bottom rigid plate-to-deformable body", plus the "self contact for the deforming body" itself. Now I don't have warning 1 and 3, only warning 2 is showing.

 

[ShadowWarrior]

Hi Jo,

I have switched back to General contact because it seems to be more robust than contact pair and a must for element removal at failure, plus my simulation runs 4 times faster with general contact than Contact Pair. Now all the previous warnings from above (read the top post) came back except warning #1 (yay!). And warning #2 is just a simple reminder, its harmless so I can ignore it.

Warning #3 is bugging me, the deformable body is placed between top and bottom discrete rigid plate (the top one is crushing the deformable body). Any tip on getting rid of this warning?

The model setup is below, note that the intersecting contact is happening between the deformable body and the bottom discrete rigid plate (both plates have zero thickness, and the deforming body is just sitting/resting on top of the plate). -