A mixed finite-element formulation for the elasto-plastic analysis of shell structures

Abstract. Mixed assumed stress finite elements for elastic-perfectly plastic materials require the solution of a Closest Point Projection (CPP) involving all element parameters integration constitutive equation. Here, dual decomposition strategy is adopted to split CPP at level into series CPPs points and in nonlinear system equations over element. The tested with four nodes mixed shell element, named MISS-4, characterised by an equilibrated interpolation displacement field only along its boundaries. recovered elasto-plastic preserves advantages namely it accurate coarse meshes recovering equilibrium path evaluating limit load showing quadratic rate convergence.