The principle of virtual work states that the equilibrium of the structure requires that for any virtual displacement
field imposed on the structure, the sum of the virtual work of the internal and the inertial forces is equal to the total virtual work of the external loads, which results in the following weak form integral equation:
In viewing the televised commentators these last several days, I have noticed that the demagogues, of two or three decades ago, have re-emerged from their political grottoes to advocate, among other things, the virtual displacement
of our civil liberties, the resumption of the assassination of heads of state and the granting of unfettered power or authority to certain governmental agencies, all in the name of ``protecting our way of life.
0] and [GAMMA] stand respectively for the volume of the undeformed membrane and the surface of the deformed membrane, t is the external surface force due to pressure and [delta]u is a virtual displacement vector compatible with displacement boundary conditions.
e] represent respectively the real displacements, the compatible virtual displacements, and positions.
The principle of virtual displacements formulation for the dynamics equilibrium equation at t = t + [DELTA]t for the fiber can be written as
where [delta]u is the virtual displacements, [delta] [epsilon] is the corre-sponding virtual Green-Lagrange strain.