Micromechanical identification of anisotropic damage evolution laws

摘要

This paper deals with the establishment ofanisotropic conjugate force based damage evolution laws in theframework of Rice's (1971) 'normality structure'. The damagevariable is the second-order crack tensor (Kachanov, 1980),which represents preexisting Griffith microcracks in a solid. Theprincipal results include the deduced damage surfaces, potentialsand kinetic equations for the basic internal variables and damagetensor during isothermal processes. The generalized pth ordercrack tensors and qth order energy release rates are introduced.The deduction in this paper is fully independent of the specificform of the free energy of Gibbs energy functions, so the deduceddamage evolution laws have a wide applicable range includingplasticity. Using the deviatoric stress as the conjugate force, thetwo well-established anisotropic yield surfaces. Karafillis andBoyce (1993) and Hill (1950), are recovered from the deduced damage surface.