Hi all,
I was running optistruct 13.0 in order to make a correlation between a 1D and 3D model. First of all I simply created a fixed beam at one end, and the other end with a force of 1 kN. The outputs were very simple to obtain, indeed I could actually have pretty similar results in terms of stresses, displacements and constraining reactions. For the 3D the force and the constraint were applied using RBE2 elements, considering a node as independent and the ones on the cross-section of the beam as dependents, as you can see in the figures below I attached. Now the thing is, when I tried to make a correlation between a slightly different model than the one mentioned above, I couldn't obtain similar results, instead they were really different. I made a comparison between stresses, displacements and constraining reactions. The force applied was 1 kN as well, on the free end of the 'T-structure'. The section used for both 1D and 3D was an IPE360. For the beam of 1 m (the one where I applied the force) I used a freeze contact with the one of 2 m (fixed at both ends), in order to replicate the same condition of the 1D. The displacements were really different, almost 2 order of magnitudes of difference... the stresses obtained in the 1D was 4 times bigger than the one in the 3D and the constraining reactions (MRy) obtained didn't equal the real flexural moment generated by the force applied at the free end (it should equal 250000 N*mm as in the 1D, for a fixed-fixed condition). I attached all the comparisons and the .hm file if you wanna see the pre-process of the analysis. Could someone give me an explanation on this? Thanks in advance for any replies!
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