A dual decomposition of the closest point projection in incremental elasto‐plasticity using a mixed shell finite element

Mixed assumed stress finite elements (FEs) have shown good advantages over traditional displacement-based formulations in various contexts. However, their use incremental elasto-plasticity is limited by the need for return mapping schemes which preserve interpolation. For elastic-perfectly plastic materials and small deformation problems, integration of constitutive equation furnishes a closest point projection (CPP) involving all element parameters. In this work, dual decomposition strategy adopted to split problem into series CPPs at points level nonlinear system equations element, order simplify its solution. The tested with four nodes mixed shell FE, named MISS-4, characterized an equilibrated interpolation improves accuracy. Two strategies are express admissibility either terms resultants or point-wise Cauchy stresses. recovered elasto-plastic solution preserves namely it accurate coarse meshes recovering equilibrium path evaluating limit load showing quadratic rate convergence, as demonstrated numerical results.