Hi Soumyadeep Mondal,

The choice of ‘starting node’ or ‘ending node’ is not arbitrary. It defines orientation of element and is closely connected with such features as cross-section, material points, contact surfaces, etc. Each type of elements has its own discription in documentation.

You can opt node numbering to identify accordingly.

Hi Soumyadeep Mondal.

Let me share a thumb rule regarding this:

The two end nodes of a 1D element are ith node and the jth node. The jth node should be chosen such that a positive motion of the jth node along the x, y or z axis should cause tension in the 1D element. Hope this helps.