Symmetry Groups and Equivalence Transformations in the Nonlinear   Donnell-Mushtari-Vlasov Theory for Shallow Shells
  In the case of transversely only loaded shallow shells, the nonlinear Donnell-Mushtari-Vlasov theory for large deflection of isotropic thin elastic shells leads to a system of two coupled nonlinear forth-order partial differential equations known as Marguerre's equations. This system involves two arbitrary elements -- the curvature tensor of the shell middle-surface and the function of transversal load per unit surface area. In the present note, the point symmetry groups of Marguerre's equations are established, the corresponding group classification problem being solved. It is shown that Marguerre's equations are equivalent to the von Karman equations for large deflection of plates in the time-independent case and in the time-dependent case as well. It is also observed that the same holds true in respect of the field equations for anisotropic shallow shells. 
Vassil M. Vassilev