Structural Analysis Methods II: Structural Systems - Mechanics of Structures: Variational and Computational Methods - page 252

FIGURE 5.6
Structural discretization in terms of elements.
FIGURE 5.7
Global coordinates X , Y , Z and the nodal displacements and forces for the whole system.
structural analysis method. The internal forces and displacements between the nodes of an
element, e.g., a bar, are evaluated after the nodal responses are computed.
As explained in Chapter 4, the independent coordinates (displacements) essential for
completely describing the motion of a node are called the nodal degrees of freedom (DOF).
The number of DOF can vary from one element type to another. For the general solid
elements of Fig. 5.7a, each node can have three DOF: three translations (shown at node k )
U Xk ,U Yk , and U Zk . There are also three corresponding forces (shown at node j ) P Xj ,P Yj ,
and P Zj . For the shell elements of Fig. 5.7b, each node can have six DOF: three translations
and three rotations. Corresponding to these DOF will be three forces and three moments.