Fracture mechanics of micro samples: Fundamental considerations

Pippan, Reinhard; Wurster, Stefan; Kiener, Daniel

doi:10.1016/j.matdes.2018.09.004

Cited by 92 publications

(36 citation statements)

References 87 publications

(137 reference statements)

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“…Atomic simulations and small-scale experiments can provide enormous contribution when investigating, for example, the role of dislocations, microstructure, and short-crack growth. When dealing with fatigue, it should be expected a different size of the fracture process zone, since the physical processes involved are different than those of ideal brittle fracture, and occur at a different scale level [44].…”

Section: Final Remarks and Future Challengesmentioning

confidence: 99%

“…2, the so-called fracture process zone (FPZ), defined as the zone where nonlinear phenomena appear and the discrete motion of atoms is highly concentrated, is assumed as the control volume V FPZ . The FPZ is considered to be the material characteristic zone that controls the fracture in the case of ideal brittle materials[27,44]. For simplicity, in the case of a crack under mode I loading, it is described by a radius R FPZ centered at the crack tip, and its length is determined later by analyzing the atomic SED distribution in the results section 4.1.…”

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confidence: 99%

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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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Section: Final Remarks and Future Challengesmentioning

confidence: 99%

mentioning

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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“…Описанные методы и приемы опробованы и использовались на макрооднородных монокристаллических, аморфных, композитных материалах, высокоэнтропийных и интерметаллических сплавах [119,163,164], пленочных керамических покрытиях (как для определения их собственных свойств, так и энергии адгезии к подложке) [193][194][195]. В [196][197][198] этими методами определяли условия перехода от вязкого к хрупкому разрушению (в частности, температуру и размеры пластической зоны в вершине трещины), а в [199] -закономерности водородного охрупчивания.…”

Section: разрушение в микро- субмикрои наношкалеunclassified

Наноиндентирование И Механические Свойства Материалов В Субмикро- И Наношкале. Недавние Результаты И Достижения (О Б З О Р)

Головин¹

2021

Физика Твердого Тела

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The review discusses the details of various materials mechanical behavior in submicro- and nanoscale. Significant advances in this scope result from the development of wide family of load based precise nanotesting techniques called nanoindentation. But nowadays, nanomechanical properties are studied not only by nanoindentation techniques in narrow sense, i.e. local loading of macro, micro and nanoscale objects. Nanomechanical load testing is discussed here within a wider scope employing precise deformation measurement with nanometer scale resolution caused by various types of low load application to the object under study including uniaxial compression or extension, shearing, bending or twisting, optionally accompanied by in situ monitoring sample microstructure using scanning and transmission electron microscopy and Laue microdiffraction technique. The main courses of experimental techniques development in recent ten years along with the results obtained using them in single, poly and nano crystalline materials, composites, films and coatings, amorphous solids and such biomaterials as tissues, living cells and macromolecules are described. Special attention is paid to deformation size effects and atomic mechanisms in nanoscale. This review is a natural continuation and development of the review published at Fiz.Tverd.Tela vol.50, issue 12, 2008 of the same author that discusses details of nanomechanical properties of solids. Current review includes wider range of nanomechanical testing concepts and recent achievements in the scope. The work was supported by RFBR grant for project #19-12-50235.

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“…Small size components, e.g., at the nanometer scale, can be fabricated with different shapes including features such as notches and may have defects such as cracks [1,2]. These circumstances have brought problems commonly addressed by fracture mechanics and fatigue theory to a completely new scale level, raising several new questions, experimental challenges, but also attractive new scientific possibilities [3][4][5]. The demand for static and fatigue assessment of nanoscale components is increasing, on the one hand, and the validity of continuum-based approaches is questioned on the other.…”

Section: Introductionmentioning

confidence: 99%

Brittle Failure of Nanoscale Notched Silicon Cantilevers: A Finite Fracture Mechanics Approach

Gallo

Sapora

2020

Applied Sciences

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The present paper focuses on the Finite Fracture Mechanics (FFM) approach and verifies its applicability at the nanoscale. After the presentation of the analytical frame, the approach is verified against experimental data already published in the literature related to in situ fracture tests of blunt V-notched nano-cantilevers made of single crystal silicon, and loaded under mode I. The results show that the apparent generalized stress intensity factors at failure (i.e., the apparent generalized fracture toughness) predicted by the FFM are in good agreement with those obtained experimentally, with a discrepancy varying between 0 and 5%. All the crack advancements are larger than the fracture process zone and therefore the breakdown of continuum-based linear elastic fracture mechanics is not yet reached. The method reveals to be an efficient and effective tool in assessing the brittle failure of notched components at the nanoscale.

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Fracture mechanics of micro samples: Fundamental considerations

Cited by 92 publications

References 87 publications

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

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

Наноиндентирование И Механические Свойства Материалов В Субмикро- И Наношкале. Недавние Результаты И Достижения (О Б З О Р)

Brittle Failure of Nanoscale Notched Silicon Cantilevers: A Finite Fracture Mechanics Approach

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