Surface effect induced thickness-dependent stress intensity factors of nano-thickness cracked metal plates

SH Dong and XL Fang and PS Yu and JH Zhao, ENGINEERING FRACTURE MECHANICS, 261, 108235 (2022).

DOI: 10.1016/j.engfracmech.2022.108235

Fracture toughnesses of cracked plates strongly depend on their thicknesses at the macroscale in available experiments, where the main reason has been answered well using the threedimensional constraint theory. However, main factors dominating the thickness-effect fracture performance of nano-thickness cracked plates are still not clear. In this study, the surface effect addressed as a function of the bulk surface energy density and surface relaxation parameter is introduced into our theoretical model to characterize fracture properties of nano- thickness cracked metal plates. Equations of both stress intensity factors (SIFs) and crack-tip stress fields are derived by the principle of virtual work. By comparison with the results of molecular dynamics simulations, finite element method as well as the Gurtin and Murdoch surface model, our theoretical model exhibits better predictions with numerical simulations. Moreover, all results show that the effect of the surface property on SIFs is obvious only when the thickness of a plate is smaller than 10 nm. This study should be of great help for understanding the fracture mechanism of nano-thickness cracked metal plates.

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