Elastic-plastic-damage constitutive models with coupling internal variables (Q1911060)

The paper describes the elastic-plastic damage constitutive behaviour by use of coupling internal variables. This approach has several consequences on the description of the material behaviour: (i) the tangent stiffness matrix is symmetric; (ii) the softening behaviour can be reproduced as a consequence of the material degradation due to the damage, rather than a ``negative'' hardening; (iii) anisotropic elastic degradation can be accounted for by properly defining the material free energy parameters; (iv) it is possible to account for the stress relaxation phenomenon exhibited by a bar specimen subjected to strain-driven load cycles. The validity of the proposed material model is indicated by simple results, relative to uniaxial stress states.