Hello,

I hope it's no problem, if I refer to this Post as I am facing similar difficulties.

I am trying to model a four Point Bending Beam made from FRC. I am using Gid Science in combination with ATENA Studio and "Cementious 2 user" as material model. The Model is a 3D Beam.
My first attempt was similar to the 2D Tutorial for FRC. I applied the same displacement on each loading plate. As the main Crack didn't developed symetricaly I got positive Forces in one of the boundary plates (Which wouldn't happen in reality)

Now I tried to model the beam of the Testing machine, which is able to rotate and therefore a uneven displacement of the loading plates is possible and therefore no pulling at the boundary loading plate can happen.

I tried to model the hinge by the conection of the beam of the testing machine with the loading plates via "fixed contact for line".

When I am trying to run the analysis now a warning message in Gid appears: "

',4MPa' Expected identifier at position 1
Warning: Some selection of condition Fixed_Contact_for_ MASTER has zero size. ContactName =Prüfmaschine links
Warning: Some selection of condition Fixed_Contact_for_ MASTER has zero size. ContactName =Prüfmaschine rechts
Warning: Some selection of condition Fixed_Contact_for_ SLAVE has zero size. ContactName =Prüfmaschine links
Warning: Some selection of condition Fixed_Contact_for_ SLAVE has zero size. ContactName =Prüfmaschine rechts
Info: Input file was written and is executed in AtenaStudio 

Moreover ATENA Studio won't start at all, stating:
"Can not Start analysis - Input file was not specified or doesn't exist"

I would highly apreciate your help. Thanks in advance.

Nils Rittel

Dear ali, as already explained, if you seek help with your particular modelling, please follow Troubleshooting, 2.1.1 to send us your model etc. - above all, sketches illustrating how the load distribution steel girder can move.

If 2 equal forces are the best approximation, you can apply 2 force loads and use the Arc Length solution method, see also Troubleshooting, 2.4.6.1.

Alternatively, you can include the girder in your model, and apply a single prescribed displacement.

Regards.

Thank you for your response,

The load from the test machine was transferred through a stiff steel girder onto the test beam in the form of two equally concentrated loads. Means single piston

Regards

Dear ali,
if you seek help/advice/comment related to your particular model, please follow ATENA Troubleshooting, 2.1.1 to send us your model along with information about what you are modelling (sketches/photos+explanation).

In this case, it is important how the load is distributed in the experiment - 2 pistons with the same pressure? A single piston + some distribution beam (how much free or blocked are its rotations)? 2 pistons with identical displacement? Something else?

Regards.