Effects of gas-pore sizes and locations on fatigue failure: A peridynamic study

Due to complicated features of gas-pores and great dispersions of fatigue lifetimes in additively manufactured metals, it is cumbersome to reveal the exact effects of gas-pores on fatigue failure by purely analyzing experiment data. In this paper, two-dimensional peridynamic virtual fatigue experiments (PD-VFE) are performed to investigate the effects of a singular circular gas-pore on the fatigue failure in smooth specimens. PD-VFE well captures three different modes of fatigue crack initiation (FCI), which are revealed to dominate the gas-pore impacts on fatigue lifetimes. Effects of two typical features of gas-pores, i.e. locations and sizes, are also clarified; to be specific, gas-pore location is the major factor to decide FCI mode and subsurface gas-pore is the most dangerous, while the role of gas-pore size is to scale the impacts of gas-pore location on fatigue lifetimes. The above PD-VFE results accord with experiment data in variation tendency, and can also explain assumptions and simplifications in Murakami approach.