AN INCREMENTAL STRESS-BASED CONSTITUTIVE MODELING ON ANISOTROPIC DAMAGED MATERIALS

An 'incremental form' of anisotropic damage constitutive equation is p roposed both for brittle and ductile materials. Based on the concept o f irreversible thermodynamics that damage processes are history indepe ndent coupled with irreversible energy dissipation, two types of defin ition for damage representation are established, known as damage tenso r D and damage strain tensor epsilon(d), to describe constitutive resp onses of damaged materials. A state variable coupled with damage and o ther observable state variables, i.e. epsilon(d), is formulated separa tely from other internal variables and defined as an equivalent damage variable. A constitutive relation due to damage is finally formulated by introducing 'damage flow potential function' employing the theory of irreducible integrity bases. A clear physical representation based on theoretical foundations and rigorous mathematical arguments of the conventional damage models defined in terms of 'damage effect tensor M (D)' is also elucidated. Validity of the proposed model is verified by comparing with the formulations of conventional damage effect tensor. A plastic potential function coupled with damage is also introduced b y employing the anisotropic plastic flow theory, so that the proposed damage model can be applied to characterize a wide range of damage pro blems of practical engineering interest.