Evaluation of residual curvature in two-point bent glass fibers

Lezzi, Peter J.; Tomozawa, M.; Blanchet, Thierry A.

doi:10.1016/j.jnoncrysol.2012.12.046

Cited by 11 publications

(24 citation statements)

References 14 publications

(33 reference statements)

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“…(b) for the sodium aluminosilicate glass. Also shown on each plot is the corresponding effective surface stress relaxation diffusion coefficients measured in water at low temperatures, 23°C–90°C for soda‐lime silicate glass and at 23°C for the sodium aluminosilicate glass by a fiber bending method . For the sodium aluminosilicate glass it appears that the entire range of water diffusion data can be fit by an Arrhenius relationship with an activation energy Δ E = 62 kJ/mol.…”

Section: Water Diffusion Coefficient Of Sodium Aluminosilicate Glassmentioning

confidence: 99%

“…(a) Low‐temperature water‐related diffusion data for soda‐lime silicate glass. Data include water diffusion in terms of hydroxyl (‐ ‐ ‐), alkali leaching diffusion coefficient (▲), as well as surface stress relaxation diffusion coefficients (♦) measured by a fiber bending method . (b) Water‐related diffusion data for 26Na 2 O–11Al 2 O 3 –63SiO 2 (mol%).…”

Section: Water Diffusion Coefficient Of Sodium Aluminosilicate Glassmentioning

confidence: 99%

“…(b) Water‐related diffusion data for 26Na 2 O–11Al 2 O 3 –63SiO 2 (mol%). Data include water diffusion in terms of hydroxyl (▲,●), alkali leaching diffusion coefficient (■) as well as surface stress relaxation diffusion coefficient (♦) measured at 23°C by a fiber bending method . For both glass types, the effective surface stress relaxation diffusion coefficient, D s , is found to be nearly 1–3 orders of magnitude faster than water‐related diffusion at room temperature.…”

Section: Water Diffusion Coefficient Of Sodium Aluminosilicate Glassmentioning

confidence: 99%

“…Data include water diffusion in terms of hydroxyl (---), alkali leaching diffusion coefficient (▲), as well as surface stress relaxation diffusion coefficients (♦) measured by a fiber bending method. 33 (b) Water-related diffusion data for 26Na 2 O-11Al 2 O 3 -63SiO 2 (mol%). Data include water diffusion in terms of hydroxyl (▲,•), alkali leaching diffusion coefficient (■) as well as surface stress relaxation diffusion coefficient (♦) measured at 23°C by a fiber bending method.…”

Section: (2) Shielding Stress Intensity Factor Due To Modified Stressmentioning

confidence: 99%

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Modeling Slow Crack Growth Behavior of Glass Strengthened by a Subcritical Tensile Stress Using Surface Stress Relaxation

et al. 2015

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Glasses exhibit slow crack growth under stress intensities below the fracture toughness in the presence of water vapor or liquid water. It has been observed by several authors that when an oxide glass with a large crack is held under a subcritical stress intensity (where no slow crack growth occurs) in room‐temperature water vapor or liquid water, upon reloading to a higher stress intensity, a finite restart time is observed prior to measurable crack extension. This phenomenon of apparent strengthening, or crack arrest, has been attributed to concepts such as corrosive dissolution of the crack tip, crack tip blunting, or water diffusion, and subsequent swelling of the material around the crack tip. Recently, a newly observed surface stress relaxation process that is aided by molecular water diffusion was used to improve the mechanical strength of glass fibers and to explain the subsurface compressive stress peak observed in ion‐exchange strengthened glasses. The same process is employed here to explain these delayed slow crack growth data. A simple mathematical model has been developed utilizing water‐assisted surface stress relaxation and fracture mechanics. Predictions of restart times using the model agreed well with published experimental data, indicating that surface stress relaxation is responsible for the anomalous delayed slow crack growth behavior.

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Section: Water Diffusion Coefficient Of Sodium Aluminosilicate Glassmentioning

confidence: 99%

Section: Water Diffusion Coefficient Of Sodium Aluminosilicate Glassmentioning

confidence: 99%

Section: Water Diffusion Coefficient Of Sodium Aluminosilicate Glassmentioning

confidence: 99%

Section: (2) Shielding Stress Intensity Factor Due To Modified Stressmentioning

confidence: 99%

See 2 more Smart Citations

Modeling Slow Crack Growth Behavior of Glass Strengthened by a Subcritical Tensile Stress Using Surface Stress Relaxation

et al. 2015

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“…Further, surface stress relaxation has been shown to occur for all oxide glass types and is not limited to glasses containing mobile alkali ions. 28 (3) Surface Stress Relaxation and the Fatigue Limit It is suggested that the effect of the surface stress relaxation diffusion process becomes large enough to influence the behavior of slowly growing cracks when the stress intensity is low, i.e., applied K P approaching down towards K o . 26 More recently, the surface stress relaxation mechanism was combined with a simple fracture mechanics based model to explain the apparent strengthening (or increasing delay time to repropagate a crack under a high stress intensity) for glass aged at subcritical stress intensity factors.…”

Section: Introductionmentioning

confidence: 99%

Origin of the Static Fatigue Limit in Oxide Glasses

2016

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Oxide glasses exhibit slow crack growth under stress intensities below the fracture toughness in the presence of water vapor or liquid water. The log of crack velocity decreases linearly with decreasing stress intensity factor in Region I. For some glasses, at a lower stress intensity, Ko, log v asymptotically diminishes where there is no measurable crack growth. The same glasses exhibit static fatigue, or a decreasing strength for increasing static loading times, as cracks grow and stress intensity eventually reaches the fracture toughness. In this case, some glasses exhibit a low stress below which no fatigue/failure is observed. The absence of slow crack growth under a low stress intensity factor is called the fatigue limit. Currently, no satisfactory explanation exists for the origin of the fatigue limit. We show that the surface stress relaxation mechanism, which is promoted by molecular water diffusion near the glass surface, may be the origin of the fatigue limit. First, we hypothesize that the slowing down of slow crack growth takes place due to surface stress relaxation during slow crack growth near the static fatigue limit. The applied stress intensity becomes diminished by a shielding stress intensity due to relaxation of crack tip stresses, thus resulting in a reduced crack velocity. This diminishing stress intensity factor should result in a crack growth rate near the static fatigue limit that decreases in time. By performing Double Cantilever Beam crack growth measurements of a soda‐lime silicate glass, a decreasing crack growth rate was measured. These experimental observations indicate that surface stress relaxation is causing crack velocities to asymptotically become immeasurably small at the static fatigue limit. Since the surface stress relaxation was shown to take place for various oxide glasses, the mechanism for fatigue limit explained here should be applicable to various oxide glasses.

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