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
In this paper, a new model to describe the dynamic ductile fracture is proposed. The constitutive relation of the elastic-viscoplastic matrix has an overstress form given by previous authors. A dynamic loading surface...In this paper, a new model to describe the dynamic ductile fracture is proposed. The constitutive relation of the elastic-viscoplastic matrix has an overstress form given by previous authors. A dynamic loading surface at constant equivalent strain rate(with the volumetric part also taken into account) is derived and an approximate expression for this dynamic loading surface is suggested. In the case where the porous material element is subjected to spherically symmetric tension, the Carroll-Holt’s model and Johnson’s model are recovered; and in the case where the strain rate sensitivity of the material tends to zero, the Gurson’s model is recovered. Moreover, the normality condition of the plastic strain rate for the dynamic loading surface is discussed, and it is shown that the normality rule is no longer valid in general. Finally, comparisons of this model with the models recently proposed by Pan, Saje and Needleman as well as by Perzyna are also presented.展开更多
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.
基金Project supported by the National Natural Science Foundation of China and Chou Peiyuan's Science Foundation of Peking University.
文摘In this paper, a new model to describe the dynamic ductile fracture is proposed. The constitutive relation of the elastic-viscoplastic matrix has an overstress form given by previous authors. A dynamic loading surface at constant equivalent strain rate(with the volumetric part also taken into account) is derived and an approximate expression for this dynamic loading surface is suggested. In the case where the porous material element is subjected to spherically symmetric tension, the Carroll-Holt’s model and Johnson’s model are recovered; and in the case where the strain rate sensitivity of the material tends to zero, the Gurson’s model is recovered. Moreover, the normality condition of the plastic strain rate for the dynamic loading surface is discussed, and it is shown that the normality rule is no longer valid in general. Finally, comparisons of this model with the models recently proposed by Pan, Saje and Needleman as well as by Perzyna are also presented.
