A mixed finite element method for the elastoplastic plate bending and buckling

We propose and test a mixed finite element method for the elastoplastic plate problem. We approximate the plane displacement with a P 1 ∩ C 0 finite element. The deflection and the curvature tensor, considered as independent degrees of freedom, are approximated with a P 1 ∩ C 0 triangular finite element. This proves insufficient for some triangulations (those not generated by three families of parallel lines) and particularly for the computation of the buckling load parameter value. The use of a P 2 ∩ C 0 finite element gives satisfactory results for the bending problem, as well as that of stability and of buckling.