ABAQUS - analysis output 1

[SofiaB]

Hello everyone!

I am analysing an SHS steel truss, simply supported, with concentrated forces (in Newtons) applied in the top nodes. The loads are applied in reference points that are constrained, type coupling, to the section of the chord. All the top nodes have a boundary condition to prevent out of plane displacements.

Since what I want to achieve is the force-displacement curve of each of the truss nodes in the history output I requested the TF2 and U2 variables. The problem is after the analysis is completed, the RF2 for that node does not show any values. Apart from that, the displacement increases but after a while reaches a plateau which does not lead to the nodes deformation that was expected. I don't know if the problem is in the wais I defined the load or if it's the type of output I requested that is incorrect, but any help solving this problem is appreciated!

I will leave some pictures for a better understatement.
Thanks in advance.

 

[FEA way]

RF is calculated only for nodes that have boundary condition applied in particular direction.

Is that a nonlinear analysis ? Do you have a reference solution for displacements ?

 

[SofiaB]

For the type of analysis, it's general static with NIgeom on.
What do you mean by reference solution for displacements?

 

[FEA way]

You’ve mentioned that displacements don’t match the expectations so I thought that you might have some reference solution to verify FEA (for example results from experiments or analytical calculations).

What about the material nonlinearity ? Which material model do you use ?

 

[SofiaB]

I just did a quick analysis in SAP2000 and indeed the displacements in the nodes confirm.
I was just trying to get the nodes to deform since that's what I am studying, and even after increasing the load I did not achieve their deformation.

As for the materials, I will leave the following pictures.

 

[oldNail]

TF2 will be the sum of concentrated force you specified (CF2) and reaction forces due to boundary conditions (RF2). RF2 should be all zero, as you are showing, since you don't have a boundary condition in that direction. Please take a look at TF2 or CF2 instead.