Molecular dynamics study on crack tip expansion behavior of FeCr alloys under cyclic loading

The molecular dynamics simulation method is used to systematically study the effect of temperature on the fatigue crack propagation of FeCr alloys. The dimensional variations of cracks were dependent on the initial central crack, but the temperature had little effect on the variation of crack width. As the number of loading cycles increases, systemic temperature influences the crack tip propagation speed. The calculated results indicate that as temperature increases from 300K to 700K, both the degree of stress concentration and the maximum stress value decrease. As the strain increases, it was found that the surface area of the void increases, and these micro-voids finally connect with the main crack to form a new crack. The variation of cracks with the number of cycles indicates that the fatigue performance of FeCr alloy is related to the ambient temperature and the propagation of the predetermined crack tip.