Quasi-micromechanical constitutive theory for brittle damaged materials under tension

One of fundamental but difficult problems in damage mechanics is the formulation of the effective constitutive relation of microcrack-weakened brittle or quasi-brittle materials under complex loading, especially when microcrack interaction is taken into account. The combination of phenomenological and micromechanical damage mechanics is a promising approach to constructing an applicable damage model with a firm physical foundation. In this paper, a quasi-micromechanical model is presented for simulating the constitutive response of microcrack-weakened materials under complex loading. The microcracking damage is characterized in terms of the orientation domain of microcrack growth (DMG) as well as a scalar microcrack density parameter. The DMG describes the complex damage and its evolution associated with microcrack growth, while the scalar microcrack density factor defining the isotropic magnitude of damage yields an easy calculation of the effects of microcrack interaction on effective elastic moduli. Project supported by the National Natural Science Foundation of China (19891180).