Damage and failure due to distributed microcracks or microvoids are on the challenging frontiers of solid mechanics. This appeals strongly to tools not yet fully developed in continuum damage mechanics, in particular ...Damage and failure due to distributed microcracks or microvoids are on the challenging frontiers of solid mechanics. This appeals strongly to tools not yet fully developed in continuum damage mechanics, in particular to irreversible statistical thermodynamics and a unified macroscopic equations of mechanics and kinetic equations of microstructural transformations. This review provides the state of the art in statistical microdamage mechanics. (1) It clarifies on what level of approximation continuum damage mechanics works. Particularly,D-level approximation with dynamic function of damage appears to be a proper closed trans-scale formulation of the problem. (2) It provides physical foundation of evolution law in damage mechanics. Essentially, the damage-dependent feature of the macroscopic evolution law is due to the movement of microdamage front, resulting from microdamage growth. (3) It is found that intrinsic Deborah numberD *, a ratio of nucleation rate over growth rate of microdamage, is a proper indication of critical damage in damage mechanics, based on the idea of damage localization. (4) It clearly distinguishes the non-equilibrium damage evolution from equilibrium phase transition, like percolation.展开更多
The statistical evolution of microvoids under high stress triaxiality is investigated. Based on the expression for the void growth rate in a power-law viscous matrix and the balance law of microvoids’ number, the evo...The statistical evolution of microvoids under high stress triaxiality is investigated. Based on the expression for the void growth rate in a power-law viscous matrix and the balance law of microvoids’ number, the evolution of microvoids’ number density under dynamic loading is studied. Thus, the si2E distribution functions of microvoids are found from the theoretical analysis, and the effect of strain rate-sensitivity of the matrix on the evolution of microvoids is examined. The present theoretical analysis may provide a reasonable explanation for the experimental phenomena observed by previous researchers.展开更多
基金The project supported by the National Natural Science Foundation of China (19891180-02, 19972004) Major State Research Project (G200007735)
文摘Damage and failure due to distributed microcracks or microvoids are on the challenging frontiers of solid mechanics. This appeals strongly to tools not yet fully developed in continuum damage mechanics, in particular to irreversible statistical thermodynamics and a unified macroscopic equations of mechanics and kinetic equations of microstructural transformations. This review provides the state of the art in statistical microdamage mechanics. (1) It clarifies on what level of approximation continuum damage mechanics works. Particularly,D-level approximation with dynamic function of damage appears to be a proper closed trans-scale formulation of the problem. (2) It provides physical foundation of evolution law in damage mechanics. Essentially, the damage-dependent feature of the macroscopic evolution law is due to the movement of microdamage front, resulting from microdamage growth. (3) It is found that intrinsic Deborah numberD *, a ratio of nucleation rate over growth rate of microdamage, is a proper indication of critical damage in damage mechanics, based on the idea of damage localization. (4) It clearly distinguishes the non-equilibrium damage evolution from equilibrium phase transition, like percolation.
基金Laboratory for Nonlinear Mechanics of Continuous Media(Institute of Mechanics,Chinese Academy of Sciences)Doctoral Program Foundation of the State Education Commission of China.
文摘The statistical evolution of microvoids under high stress triaxiality is investigated. Based on the expression for the void growth rate in a power-law viscous matrix and the balance law of microvoids’ number, the evolution of microvoids’ number density under dynamic loading is studied. Thus, the si2E distribution functions of microvoids are found from the theoretical analysis, and the effect of strain rate-sensitivity of the matrix on the evolution of microvoids is examined. The present theoretical analysis may provide a reasonable explanation for the experimental phenomena observed by previous researchers.
