Effects of surface crack on the mechanical properties of Silica: A molecular dynamics simulation study

Chowdhury, Sanjib C.; Wise, Ethan A.; Ganesh, Raja; Gillespie, John W.

doi:10.1016/j.engfracmech.2018.12.025

Cited by 61 publications

(22 citation statements)

References 28 publications

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“…Motivated by findings from several recent attempts to homogenize the fracture toughness, in this work we decouple the plastic disspation from fracture degradation and propose a novel coalescence dissipation to model the coupling between plasticity and fracture. Rodriguez et al [32], Chowdhury et al [33], and Vo et al [34] found that ligament length, shape, and orientation of defects at the micro-scale influence the Mode-I fracture toughness. We postulate that the presence of plastic flow (or dislocations at the micro-scale) alters those properties related to defects, and at the continuum level, some configurational energy has been dissipated prior to crack initiation, effectively reducing the fracture toughness.…”

Section: Introductionmentioning

confidence: 99%

A variational phase-field model For ductile fracture with coalescence dissipation

Talamini

Stershic

et al. 2021

Comput Mech

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A novel phase-field for ductile fracture model is presented. The model is developed within a consistent variational framework in the context of finite-deformation kinematics. A novel coalescence dissipation introduces a new coupling mechanism between plasticity and fracture by degrading the fracture toughness as the equivalent plastic strain increases. The proposed model is compared with a recent alternative where plasticity and fracture are strongly coupled. Several representative numerical examples motivate specific modeling choices. In particular, a linear crack geometric function provides an "unperturbed" ductile response prior to crack initiation, and Lorentz-type degradation functions ensure that the critical fracture strength remains independent of the phase-field regularization length. In addition, the response of the model is demonstrated to converge with a vanishing phase-field regularization length. The model is then applied to calibrate and simulate a three-point bending experiment of an aluminum specimen with a complex geometry. The effect of the proposed coalescence dissipation coupling on simulations of the experiment is first investigated in a two-dimensional plane strain setting. The calibrated model is then applied to a three-dimensional calculation, where the calculated load-deflection curves and the crack trajectory show excellent agreement with experimental observations. Finally, the model is applied to simulate crack nucleation and growth in a specimen from a recent Sandia Fracture Challenge.

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Section: Introductionmentioning

confidence: 99%

A variational phase-field model For ductile fracture with coalescence dissipation

Talamini

Stershic

et al. 2021

Comput Mech

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“…It is very important for MD simulation to choosing the right interaction potential function, because it determines the accuracy of simulation result. 36 Only two kinds of atomic interactions, Si-Si and Si-C, need to be considered in this study, because the diamond indenter is set as a rigid body. The details of potential function used in this work are shown in Table 2.…”

Section: Simulation Methodsmentioning

confidence: 99%

Mechanism of crack evolution in nano-indentation of single crystal silicon by atomistic simulations and theoretical analysis

Zhou

Dai

2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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The molecular dynamics (MD) model of nano-indentation process was established to study the crack evolution in single crystal during nano-indentation. Two workpieces with different cracks and one workpiece with no crack were selected for indentation simulation in this study. The parameters of atom displacement, coordination number (CN), temperature, potential energy and loading force in the indentation process are analyzed in detail. Cracks were found to close during nano-indentation. Two modes of crack closure are observed: cooperative displacement and indentation failure. The existence of cracks will affect the size of transformation zone and the coordination number of atoms after indentation. Besides, the existence of cracks will reduce the increase of temperature and potential energy, and the closing mode of cracks is found to affect the value of indentation load. In addition, the change of stress with indentation depth at crack tip is calculated by theoretical model. The calculated stress curves reveal the evolution trend of cracks during indentation. These results provide guidance for the production of silicon wafer with higher surface quality.

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“…Moreover, an inelastic region of 3 nm in diameter was noticed from the stress fields and dissipation energies. In silica glass, Chowdhury et al [158] investigated the fracture mechanisms and the influence of surface crack on the mechanical attributes, where they figured out how the strength of fracture is greatly affected by the fracturing.…”

Section: Brittle Materials—advances In Fracture Study At Nanoscalementioning

confidence: 99%

A Review on Brittle Fracture Nanomechanics by All-Atom Simulations

Patil

Heider

2019

Nanomaterials

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Despite a wide range of current and potential applications, one primary concern of brittle materials is their sudden and swift collapse. This failure phenomenon exhibits an inability of the materials to sustain tension stresses in a predictable and reliable manner. However, advances in the field of fracture mechanics, especially at the nanoscale, have contributed to the understanding of the material response and failure nature to predict most of the potential dangers. In the following contribution, a comprehensive review is carried out on molecular dynamics (MD) simulations of brittle fracture, wherein the method provides new data and exciting insights into fracture mechanism that cannot be obtained easily from theories or experiments on other scales. In the present review, an abstract introduction to MD simulations, advantages, current limitations and their applications to a range of brittle fracture problems are presented. Additionally, a brief discussion highlights the theoretical background of the macroscopic techniques, such as Griffith’s criterion, crack tip opening displacement, J-integral and other criteria that can be linked to the fracture mechanical properties at the nanoscale. The main focus of the review is on the recent advances in fracture analysis of highly brittle materials, such as carbon nanotubes, graphene, silicon carbide, amorphous silica, calcium carbonate and silica aerogel at the nanoscale. These materials are presented here due to their extraordinary mechanical properties and a wide scope of applications. The underlying review grants a more extensive unravelling of the fracture behaviour and mechanical properties at the nanoscale of brittle materials.

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Effects of surface crack on the mechanical properties of Silica: A molecular dynamics simulation study

Cited by 61 publications

References 28 publications

A variational phase-field model For ductile fracture with coalescence dissipation

A variational phase-field model For ductile fracture with coalescence dissipation

Mechanism of crack evolution in nano-indentation of single crystal silicon by atomistic simulations and theoretical analysis

A Review on Brittle Fracture Nanomechanics by All-Atom Simulations

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