Jean Lemaître proposed a continuous damage mechanics model for ductile fracture, based on a continuum damage variable, effective stress, and thermodynamics. The model describes isotropic ductile plastic damage, where damage increases linearly with equivalent strain and is influenced by triaxiality through a damage equivalent stress. The model is identified using changes in the elasticity modulus induced by damage and compared with the McClintock and Rice-Tracey models and experimental data to assess the effect of triaxiality on strain to rupture. The model introduces a damage variable D, defined as the ratio of the original area to the effective resisting area, and is related to the effective stress. The model assumes isotropic damage, where cracks and voids are equally distributed in all directions, and that the mechanical effects of cavities and microcracks are the same in tension and compression. The model also incorporates the hypothesis of strain equivalence, where the strain behavior of a damaged material is represented by the constitutive equations of an undamaged material with effective stress replacing the actual stress. The model is derived from thermodynamics, with the free-energy function assumed to be a convex function of all observable and internal variables. The model includes a damage criterion, where the damage process leads to the initiation of a macrocrack when the damage variable reaches a critical value. The model also incorporates a potential of dissipation, allowing for the derivation of constitutive equations for dissipative variables. The model is applied to several metals, showing that the damage variable D is linear with strain and is strongly influenced by triaxiality. The model is validated against experimental data and compared with the McClintock and Rice-Tracey models, demonstrating its effectiveness in predicting ductile fracture behavior. The model is also applied to radial loading, where the damage variable is related to the accumulated plastic strain. The model's parameters are identified through elasticity modulus changes, and the model is shown to be effective in predicting ductile fracture in metals. The model is summarized as a linear function of strain with a strong dependence on triaxiality, and is validated against experimental data and other models.Jean Lemaître proposed a continuous damage mechanics model for ductile fracture, based on a continuum damage variable, effective stress, and thermodynamics. The model describes isotropic ductile plastic damage, where damage increases linearly with equivalent strain and is influenced by triaxiality through a damage equivalent stress. The model is identified using changes in the elasticity modulus induced by damage and compared with the McClintock and Rice-Tracey models and experimental data to assess the effect of triaxiality on strain to rupture. The model introduces a damage variable D, defined as the ratio of the original area to the effective resisting area, and is related to the effective stress. The model assumes isotropic damage, where cracks and voids are equally distributed in all directions, and that the mechanical effects of cavities and microcracks are the same in tension and compression. The model also incorporates the hypothesis of strain equivalence, where the strain behavior of a damaged material is represented by the constitutive equations of an undamaged material with effective stress replacing the actual stress. The model is derived from thermodynamics, with the free-energy function assumed to be a convex function of all observable and internal variables. The model includes a damage criterion, where the damage process leads to the initiation of a macrocrack when the damage variable reaches a critical value. The model also incorporates a potential of dissipation, allowing for the derivation of constitutive equations for dissipative variables. The model is applied to several metals, showing that the damage variable D is linear with strain and is strongly influenced by triaxiality. The model is validated against experimental data and compared with the McClintock and Rice-Tracey models, demonstrating its effectiveness in predicting ductile fracture behavior. The model is also applied to radial loading, where the damage variable is related to the accumulated plastic strain. The model's parameters are identified through elasticity modulus changes, and the model is shown to be effective in predicting ductile fracture in metals. The model is summarized as a linear function of strain with a strong dependence on triaxiality, and is validated against experimental data and other models.