Topic: Contact - master-slave pair/group BC

Hi there,

I am currently modelling a CFRP to concrete bond delamination problem using multiple layers of FRP material bonded to concrete using interface elements. I am currently recieving several of the following warning messages:

Invalid master-slave pair/group BC, master(s) 29109 29110 29111 29112 29113 29114 29115 29116 29117 29118 29119 29001 29055 29002 29009 29010 29011 29012 29013 29014 29015 29016 29017 29018 29019 29057 29058 29059 29060 29061 29062 29063 29064 29065 29066 29067 29068 29006 29069 29005 29020 29021 29022 29023 29024 29025 29026 29027 29028 29029 29030 29070 29071 29072 29073 29074 29075 29076 29077 29078 29079 29080 29081 , at least one dof of slave: 66112 could not be constrained,  specified in support id: 1, load case id 738197852, name: VOLUME 402653213 SURFACE 603979950 to VOLUME 402653250 SURFACE 603980176; BC ignored.

I read a similar post and the response on this forum, it was said to occur for Degrees of Freedom (DoFs) of nodes on a contact, that are already fixed.

I still cannot figure our how to resolve this warning. I currently have over 700 contacts in my model, and the warning message does not indicate which contact/or contacts are the problematic ones. Can you please give me some practical guidance on how to resolve this issue? Is this due to incorrect automatic Master/slave designation which I must manually change?



Re: Contact - master-slave pair/group BC

Dear Robin, please read the paragraph
I get the warning "Invalid master-slave" during analysis, what is wrong?
at our ATENA Known Problems page

Re: Contact - master-slave pair/group BC

thanks for your response

4 (edited by 2020-08-31 22:13:09)

Re: Contact - master-slave pair/group BC


There is a way to use master-slave conditions in surfaces that are separate over a distance? (see … sp=sharing The surfaces should have equal out-of-plane displacements (z-axis)

Maybe in 'Problem data'->'Global options'->'Master-slave distance manual' meet this purpose. However, I'm afraid I'm not using it correctly. Should I put the name of the boundary condition and the distance between the 2 surfaces?

Thank you in advance,
Best regards


Re: Contact - master-slave pair/group BC

Dear Marcos,
I assume you have already read about Fixed Contact in ATENA-GiD User's, 5.2 Conditions.

Yes, to connect Master and Slave which are relatively far from each other (i.e., not touching), you need to define an item in the Master-slave distance manual table, under the name of the M-S connection.

As far as I remember, the 1st choice is to set the Distance to a negative value, with absolute value somewhat larger than the distance between the 2 surfaces being connected (see also the help bubbles).


Re: Contact - master-slave pair/group BC

Thanks Dobromil.

Now it worked with negative values and larger distances.

Best regards