Endochronic Theory of Continuum Damage Mechanics

Abstract

The constitutive framework presented accounts for the coupling between the damage process and the plastic deformation process. The model build its basis on the thermodynamic equivalence of an actual damaged continuum and an equivalent fictitious undamaged continuum. It uses damage internal state variables that are independent of the damage measure and it uses corotational derivatives of damage descriptors. An endochronic theory is used to derive explicit equations. Two intrinsic times are used. The first intrinsic time is used to describe the plastic deformation history of a material. The second intrinsic time is used to depict the damage history. The constitutive equations of this theory are continuous without discontinuities, and the yield conditions are not needed in the numerical calculation. The proposed model is verified against reported results for one-dimensional, monotonic and cyclic loading of concrete and mortar specimens subjected to uniaxial tension and compression.