Overclosure error even when the contact surfaces are far apart

[anandv1603]

Hi users,

I am simulating a seat cover assembly process and my model has a seat foam structure and a leather seat cover in ABAQUS-6.13.4.

Throughout the model, i have assigned the

Foam as Slave surface (SOLID ELEMENTS)
Leather as Master surface. (SHELL ELEMENTS)

I am using Surface-surface contact pair.

Initially a part of the leather is penetrating the foam but the contact is not active in the initial steps.
Later I pull out the leather so that there is sufficient gap between the leather and the foam. After this i activate the contact in the next step.

However during my contact activation step, immediately after the step starts, it shows "CONTACT PAIR node Overclosure too severe" though the slave and master are far apart. That too only for a couple of contact regions (I have many contact regions in the model).

Kindly suggest me what could be the reason for this..

Thanks in advance..

 

[DrBwts]

Check the shell thickness & direction (eg is the thickness about the mid-line). It could be that the thickness is over lapping the solid elements, which you wouldnt see just looking at the model

 

[anandv1603]

Hallo DrBwts,

Thanks for the reply.

I have checked that also by using the "render shell thickness" option in ABAQUS to display my .ODB model with the specified thickness. There is enough gap between the slave and Master surface even after that.
I also changed the shell normals of the problematic contact pairs and ran the simulation. Though by this way, i have no penetration error, the simulation aborts again at the start of the contact activation step stating time increment required is too less.

One more point is that the problematic contact regions are the ones that were initially penetrating the slave surface when the contacts were inactive.

Could this be a problem? But i don't think so as ABAQUS doesn't recognise any contact between them during those initial penetrating steps. When ABAQUS realizes that there is a contact, the slave and master surfaces are well apart.

 

[Boris92]

hi,

What is your contact definition? You are used small sliding or finite sliding contact?
Otherwise you can try "*Contact controls, stabilize" in step level in order to initiate the contact.

 

[anandv1603]

Hello Boris92,

I am using CONTACT PAIR, SURFACE TO SURFACE with SMALL SLIDING and default friction in contact interaction. I tried the simulation with stabilize option also but no improvement !!!