Cracks: More Than Just a Clean Break

Hellemans, Alexander

doi:10.1126/science.281.5379.943

Cited by 15 publications

(9 citation statements)

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“…[1][2][3][4] Similar ideas have been hypothesized for organic polymers, 5,6 but a more detailed insight into the role of defects in crystalline polymer and organic molecular solids has only begun to be developed. Defects or local variations in structure are expected to play an important role in limiting macroscopic properties.…”

Section: Introductionmentioning

confidence: 95%

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Defect-mediated curvature and twisting in polymer crystals

Kübel

Gonzalez-Ronda

Drummy

et al. 2000

J. Phys. Org. Chem.

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Section: Introductionmentioning

confidence: 95%

“…The simulations were performed for varying chain length N (typically [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] to simulate different defect densities. To isolate the dislocation, we constructed superlattices that topologically trap the defect into a larger, periodic unit cell.…”

Section: Defects In Polymersmentioning

confidence: 99%

Defect-mediated curvature and twisting in polymer crystals

Kübel

Gonzalez-Ronda

Drummy

et al. 2000

J. Phys. Org. Chem.

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“…However, the existence of surface or subsurface defects and inhomogeneity strongly impedes the applicability of these fragile materials [ 3 , 4 ]. In the presence of surface and subsurface defects, the measured strength of glass and other brittle materials is significantly lower than the theoretical strength value [ 5 – 7 ]. Stress concentration at defect tips can initiate crack propagation and induce fractures in these materials [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

Strength Improvement of Glass Substrates by Using Surface Nanostructures

et al. 2016

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Defects and heterogeneities degrade the strength of glass with different surface and subsurface properties. This study uses surface nanostructures to improve the bending strength of glass and investigates the effect of defects on three glass types. Borosilicate and aluminosilicate glasses with a higher defect density than fused silica exhibited 118 and 48 % improvement, respectively, in bending strength after surface nanostructure fabrication. Fused silica, exhibited limited strength improvement. Therefore, a 4-μm-deep square notch was fabricated to study the effect of a dominant defect in low defect density glass. The reduced bending strength of fused silica caused by artificial defect increased 65 % in the presence of 2-μm-deep nanostructures, and the fused silica regained its original strength when the nanostructures were 4 μm deep. In fragmentation tests, the fused silica specimen broke into two major portions because of the creation of artificial defects. The number of fragments increased when nanostructures were fabricated on the fused silica surface. Bending strength improvement and fragmentation test confirm the usability of this method for glasses with low defect densities when a dominant defect is present on the surface. Our findings indicate that nanostructure-based strengthening is suitable for all types of glasses irrespective of defect density, and the observed Weibull modulus enhancement confirms the reliability of this method.

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“…Although limited to submicron samples and very short time scales, these simulations were able to reproduce key features of crack propagation like the initial acceleration and the onset of instabilities. Nevertheless, a detailed understanding of the complex physics of crack propagation, in particular, aspects of the pattern formation process, still remain a major challenge [23].…”

Section: Introductionmentioning

confidence: 99%

Brittle fracture in viscoelastic materials as a pattern-formation process

et al. 2011

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A continuum model of crack propagation in brittle viscoelastic materials is presented and discussed. Thereby, the phenomenon of fracture is understood as an elastically induced nonequilibrium interfacial pattern formation process. In this spirit, a full description of a propagating crack provides the determination of the entire time dependent shape of the crack surface, which is assumed to be extended over a finite and self-consistently selected length scale. The mechanism of crack propagation, that is, the motion of the crack surface, is then determined through linear nonequilibrium transport equations. Here we consider two different mechanisms, a first-order phase transformation and surface diffusion. We give scaling arguments showing that steady-state solutions with a self-consistently selected propagation velocity and crack shape can exist provided that elastodynamic or viscoelastic effects are taken into account, whereas static elasticity alone is not sufficient. In this respect, inertial effects as well as viscous damping are identified to be sufficient crack tip selection mechanisms. Exploring the arising description of brittle fracture numerically, we study steady-state crack propagation in the viscoelastic and inertia limit as well as in an intermediate regime, where both effects are important. The arising free boundary problems are solved by phase field methods and a sharp interface approach using a multipole expansion technique. Different types of loading, mode I, mode III fracture, as well as mixtures of them, are discussed.

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Cracks: More Than Just a Clean Break

Cited by 15 publications

References 0 publications

Defect-mediated curvature and twisting in polymer crystals

Defect-mediated curvature and twisting in polymer crystals

Strength Improvement of Glass Substrates by Using Surface Nanostructures

Brittle fracture in viscoelastic materials as a pattern-formation process

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