Computational analysis of isotropic plasticity models

The implementation of plasticity models with general isotropic yield surfaces is discussed. The computation of the return map solution and the algorithm linearization are carried out by suitably exploiting the isotropic character of the elastic constitution and of the yield function; the consistent tangent tensor is given an intrinsic explicit representation and the relevant coefficients are provided. It is also addressed the implementation of the constitutive algorithm in the subspace defined by the plane stress condition. This is obtained only by specializing the three-dimensional formulation to a two-dimensional ambient space, with the result that the structure of the return mapping scheme and the formal expression of the consistent tangent tensor are preserved. The effectiveness of the approach is demonstrated by means of representative numerical simulations.