Biot stress and strain in thin-plate theory for large deformations

We propose a theory of nonlinear deformation of a plate on the basis of an energetically conjugate pair of the Biot stress tensors and the right stretch tensor. When the dimensionality of the problem is reduced from three to two, the classical Kirchhoff conjectures are used, the linear part is retained in the expansion of the right stretch tensor with respect to a degenerate coordinate, and no additional simplifications are assumed. Connection is obtained between the asymmetric and symmetric components of the Biot tensor; the equivalence is demonstrated of the virtual work principle with the equilibrium equations, the natural boundary conditions, and additional conditions for the dependence of asymmetric stress moment resultants on symmetric moments.