Before you code — Make a prediction
Imagine that MAPDL assigns nodes to the free end 241–255. By increasing the length
of 1.0 m a 1.2 m and refine the mesh, will they still represent the tip?
There is no guarantee. IDs describe how it was stored this meshing, not what a region physically means. Instead, the phrase “nodes located at the tip” can be expressed by geometry:
NSEL,S,LOC,X,beam_l
In this lesson we will go a step further: we will place the origin of a local system at the tip
and we will always select it with X=0. The instruction will be relative to the part,
not to the particular size of the case.