Beam type B31 is automatically solved by CCX as B31R

Pierluigi

Hello everyone,
While doing some tests to compare beam elements I came up with a pretty strange error:
I modeled a simple cantilever beam of type B31, but CCX gives me a wrong displacement of the tip.
I calculated the correct value by hand, using the internal solver and using an equivalent user beam (in CCX) and all these methods give me the same result of 2.38mm, versus the 1.79 given by CCX beam.
In the output file with extension .12d appears the following message:
----
ELEMENT 1 with label "B31 R" and with nodes:
1 2
is expanded into a "C3D8I BR" element with topology:
3 11 12 4 6 14 13 5 0 0
----
Does anyone know why CCX reads the beam type as B31R even if in the .inp is clearly defined ad B31? I guess that's the problem but I don't know how to solve it.
All related files are attached except the .12d, because unfortunately the file type is not allowed by the website.

Thanks in advance for any help,
Pier

Victor

I don't know why it shows an R there and if that really means it's B31R or not, but regarding the error, you have to refine the mesh with CCX beams, then it approaches the correct value.