Abstract: We brack through the tradilionat forms of potential energy density and complementary energy density to establish the generalized functionals and the generalized variational principles belonging to three independent argument functions by use of Lagrange multiplier method and we derived new forms of the functionals and new forms of the variational principles belonging to one or two independent argument functions.
In the course of the discussion we proved that Hu-Washizu's principle, H'ellinger-Reissner's principle and the generalized principle of Complementary energy²³ are the generalized varialional principles belonging to two independent argument functions in essence.