Dear João Dias ,

in the description of your problem you mention that the structure constitutes of beams and connectors. So keeping that in mind I cannot see why you would like to apply interactions. For example you mean that between two beams you would like to have contact?

If your structure resembles a space truss-like structure I would suggest that you use coupling constraints to assemble your parts together, in order to have more control on what you constrain.

Regards,

Anargyros

Dear Joao Dias

Constraints defined in the Interaction module define constraints on the analysis degrees of freedom, whereas constraints defined in the Assembly module define constraints only on the initial positions of instances. In the Interaction module you can constrain the degrees of freedom between regions of a model, and you can suppress and resume constraints to vary the analysis model. Currently, you can create Coupling and MPC constraint from the library of ABAQUS.

Best regards

Mehdi

I would suggest that you use coupling constraints to assemble your parts together, too.

Dear Anargyros,

I am assuming interactions because beams are not welded together: Two separate beams are connected by a different part with two holes (and no fixing such as bolts or glue), which will then be assembled by hand. This part with two holes is what I am referring to as a "connector".

Dear Mehdi and Reza,

I have defined all Interactions or Tie Constraints on the Interaction Module. I have increased my results with interactions using some Displacement/Rotation Boundary Condition in some regions of the model, but will try Coupling Constraints further.

João Dias,

I think that I miss something regarding modeling of the problem you have described. May I ask if you use 3D solid/brick finite elements of 1D beam finite elemets? If you are modeling the parts with 3D elements and the geometry including holes is preserved, then probably the use of reference points and coupling constraints is the best option. Do you have any kind of screenshot with the ABAQUS model to help as understand better?

Regards,

Anargyros

Anargyros,

I am using 3D brick elements, the parts are imported from Step files. I cannot show any screenshot or image of the actual work, but I can post a link of a very similiar mechanism:

https://s3.amazonaws.com/tentcraft-cdn/images/event-tents-and-structures/frame-tent-models/x-series/x-series-tent-framework.gif

My model is something very similiar to that, only that the "legs" are not fixed to the "brackets", instead they are just hand-assembled. They also have no kind of fixing (these canopies often have metal clip springs to fix the legs to the brackets).

Hope I could be clearer, thank you for your help.

Regards,

João

Dear João,

the image you provided was really helpful.

So if had to deal with these problem I would choose between two connecting methods:

Method A: I would define a reference point at the centre of each hole and couple the nodes of the surface that defines the hole with the reference point. After that I would make pairs of reference points and create appropriate coupling constrains between RP pairs to simulate the connection between the parts.

Method B: lets say we have a rod and a connector part. I would partition the rod into two partitions so that the one of them represents the length of the rod that enters the connector. After that I would mesh with the exact same number of elements the corresponding parts and tie the nodes of the outer surface of the partitioned part with the nodes of the inner surface of the connector.

Method B seems less realistic for your case, but is easy to perform. Method A is more accurate but requires a little more effort to do it right.

Regards,

Anargyros