A large strain one-dimensional ductile damage model for space truss analysis considering Gurson’s porous plasticity, thermal effects and mixed hardening

Abstract

In this work, a large strain one-dimensional GTN ductile damage model accounting for thermal effects and mixed hardening is developed. The Lagrangian constitutive framework is based on the Kroner–Lee decomposition together with thermodynamic principles. The damage evolution is described in terms of the porosity rate. The yield function follows the usual GTN criterion, condensed according to the uniaxial stress state. Mixed hardening behavior is expressed combing the Swift isotropic model with the Armstrong–Frederick rule for kinematic hardening. Plastic work heating is also included in terms of temperature rate. The formulation developed is implemented in a 3D truss bar finite element code. Elastic predictor and plastic correction are adopted together with time integration of the inelastic variables. The consistent tangent operator is also provided and used in the numerical algorithm. Results illustrate the performance of the proposed formulation in predicting the large-strain behavior of truss bar problems regarding the evolution of forces, stresses, strains, porosity, isotropic hardening parameter, temperature and backstress. The influence of the set of plastic parameters is investigated in detail, considering four steels. The present formulation is also compared to the corresponding isothermal, undamaged and perfectly plastic situations, highlighting the importance of using the full model.