ABSTRACT
Now suppose that there are nodes on the axis, and note that the radial displacements are constrained to vanish on the axis. For reasons shown later, it is necessary to enforce the symmetry constraints a priori in the formulation of the displacement model. In particular, suppose that node e is on the axis, with nodes e+1 and e+2 defined counterclockwise at the other vertices. The linear interpolation model is now
(9.20)
A similar formulation can be used if two nodes are on the axis of symmetry so that the u displacement in the element is modeled using only one nodal displacement, with a coefficient vanishing at each of the nodes on the axis of revolution.
