Hamilton´s principle for linear piezoelectric media

Hamilton´s principle for the linear piezoelectric continuum is presented and is shown to yield the well-established differential equations and boundary conditions of the linear theory. The Lagrange density for the piezoelectric case is shown to be the kinetic energy minus the electric enthalpy, rather than the kinetic energy minus the internal energy as in the purely elastic case. The possible application of the variational principle in obtaining approximate solutions to both homogeneous and inhomogeneous piezoelectric boundary value problems is discussed.