A Robust in situ TEM Experiment for Characterizing the Fracture Toughness of the Interface in Nanoscale Multilayers

Yan, Yabin; Sumigawa, Takashi; Kitamura, Takayuki

doi:10.1007/s11340-018-0375-6

Cited by 6 publications

(1 citation statement)

References 36 publications

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“…The cohesive force to separate the bonds was then supposed to be dependent on interatomic force-displacement relationships, i.e., interatomic potential, and later associated with the surface energy per unit area. However, it has been only recently that those concepts have been addressed systematically, due to important advancements of in-situ observation of mechanical behavior at small scales [2][3][4][5][6][7][8][9][10][11] and developments of computational techniques such as molecular dynamics supported by improvement in computational power [12][13][14]. Sumigawa et al.…”

Section: Introductionmentioning

confidence: 99%

Strain energy density approach for brittle fracture from nano to macroscale and breakdown of continuum theory

Gallo

Hagiwara

Shimada

et al. 2019

Theoretical and Applied Fracture Mechanics

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In contrast to the great success at the macroscale, fracture mechanics theory fails to describe the fracture at a critical size of several nanometers due to the emerging effect of atomic discreteness with decreasing material size. Here, we propose a novel formulation for brittle fracture, from macro-to even atomic scales, based on extended strain energy density, and give an insight into the breakdown of continuum theory. Numerical experiments based on molecular statistics (MS) simulations are conducted on single-edge cracked samples made of silicon while varying the size until few nanometers, and loaded under mode I. The strain energy density is then defined as a function of the interatomic potential and averaged over the fracture process zone. Finally, by using an attenuation function, the atomic strain energy density gradient is homogenized to allow a comparison between the continuum and discrete formulation. Results show that the fracture process zone is scale independent, confirming that the ideal brittle fracture is ultimately governed by atomic bond-breaking. A singular stress field according to continuum fracture mechanics is still also present. However, when the singular stress field length (distance from the crack tip at which the stress deviates 5% from the theoretical field of r 0.5) is in the range of 4-5 times the fracture process zone, continuum fracture mechanics fails to describe the fracture, i.e., the breakdown of continuum theory. The new formulation, instead, goes well beyond that limit.

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