| In metal material, microcrack initiation, expansion, link, is the result of main incentive failure of many high-temperature, high-pressure component in chemical engineering, electric power, nuclear power and other industries and also reduce the lifetime of interconnects. The law of microcrack evolution is one of the hot spots in the study of microstructure evolution. It is of great theoretical and engineering application value. The evolution of microcracks is related of many outside environment, such as electric field, magnetic field and stress field. This paper is focus on the effect of stress field on microcrack evolution.First of all, based on the elasticity theory and the theory of energy, the evolution of intragranular microcracks under stress is analyzed. A approximate analytical formula is derived for 2-D intragranular microcracks bifurcation.Then, the model of microcrack evolution under stress is established. Based on the finite element method for micro-structural evolution developed by Suo etc, a program which is able to simulate the surface evolution induced by surface and strain energy is developed.Finally the evolution of the intragranular, transgranular microcracks and the microcraks along grain boundarys under external load is simulated. The evolution bifurcation of the three typical microcrack is more detailed analyzed. The FEM results for the intragranular microcracks are consistent with the theoretical predictions.
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