Can generalized displacements approximate joint rotations in a solid-element model?

Yes, this will work for a model consisting only of solid elements. Suppose the position vector from joint 1 to 2 is given by (dx, dy, dz). A generalized displacement of type rotation may be defined for rotation about the Z axis, then given as Rz = dx*dUy – dy*dUx. Coefficients which define generalized displacement for Joint 1 are then (dy, -dx, 0, 0, 0, 0), and for Joint 2, (-dy, dx, 0, 0, 0, 0).

If necessary, separate rotational generalized displacements can be defined for Rx and Ry. Once defined, plots and tabular output are available.

Can generalized displacements calculate strain?

Yes, when element strain is not directly reported, strain values from joint displacements may be calculated using generalized displacements. This is done through the Define > Generalized Displacements menu.