Atomistic simulation on crack growth in a-Fe under high temperature
(0) Fracture in bcc iron (a-Fe) under different temperatures through molecular simulation has been investigated using Large-scale Atomic Molecular Massively Parallel Simulator (LAMMPS) code. The interatomic bonds of atoms are characterized using the embedded atom method interatomic potential. The simulation models were built with initial edge cracks subjecting to uniaxial constant strain rate loading. For the sake of revealing the influence of the temperature on crack growth, only one typical crack system is chosen and a temperature range from 100 K to 1200 K is considered. At different temperature, crack growth mechanism, rate, fracture profile, the evolution of the associated atomic stress fields near the crack tip and radial distribution function (RDF) during crack growth in iron single crystals were investigated and compared. The dynamic atomic velocity vectors and stress contours appear a discontinuous distribution, which illustrates the heterogeneity and uneven development of material damage. The results show that the mechanisms at the crack tip are sensitive to temperature and the boundary conditions. Mechanisms such as cleavage crack propagation and dislocation emission are observed. By proposed image adjusting technology expanded from Moire interferometry method, the dislocation slip bands describing material damage are clearly shown on screen. Based on thermal activation theory and simulation results, the effect of temperature on crack growth can be taken into account by an expression in an exponential function form which describes crystal plasticity. The coefficient and index values in expression are determined by the RDF peak value obtained from atomistic simulations. The simulation results show that the crack growth process is highly dependent on the temperature.
Molecular simulation Crack growth High temperature Radial distribution function Iron Thermal activation
Tong Liu Minshan Liu
Thermal energy engineering research center ofZhengzhou University, Zhengzhou 450002, China
国际会议
2012 International Symposium on Structural Integrity 2012国际结构完整性学术研讨会 ISSI 2012
济南
英文
229-237
2012-10-31（万方平台首次上网日期，不代表论文的发表时间）