Strengthening of E-glass fibers by surface stress relaxation

Lezzi, Peter J.; Seaman, Jared H.; Tomozawa, M.

doi:10.1016/j.jnoncrysol.2014.05.029

Cited by 20 publications

(34 citation statements)

References 22 publications

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“…Two main mechanisms have been investigated over the years: (1) thermally-activated changes to the anisotropic silica network structure initially induced by the high drawing stress during fibre manufacture [16][17][18][19], and (2) thermally-induced diffusion of water into the fibre surface leading to increased surface area and larger micropores as indicated through surface area measurements and fractography [15,[20][21][22]. Additionally, in a reverse study it was shown recently that glass fibres can be strengthened beyond their as-received strength via generation of additional surface compressive residual stresses during exposure to elevated temperatures [23].…”

Section: Introductionmentioning

confidence: 99%

Determining the mechanism controlling glass fibre strength loss during thermal recycling of waste composites

Feih

Mouritz

Case

2015

Composites Part A: Applied Science and Manufacturing

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Section: Introductionmentioning

confidence: 99%

Determining the mechanism controlling glass fibre strength loss during thermal recycling of waste composites

Feih

Mouritz

Case

2015

Composites Part A: Applied Science and Manufacturing

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“…When the applied tensile stress is removed after cooling, the fiber acquires a surface compressive stress with nearly the same magnitude as the applied tensile stress, compensated by a low tensile stress inside the fiber bulk. The strengthening of fibers by this method has been demonstrated for silica glass, E‐glass, and soda‐lime silicate glass . Fast surface stress relaxation has also been used to explain various mysterious phenomena related to the mechanical strength of glass, such as surface degradation of compressive stress made by ion‐exchange, crack arrest, and the static fatigue limit …”

Section: Introductionmentioning

confidence: 99%

Modeling birefringence in SiO₂ glass fiber using surface stress relaxation

et al. 2019

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The retardance of silica glass fibers was evaluated using photoelastic techniques. Here, surface birefringence in glass fibers is shown to be a consequence of surface stress relaxation for as‐received fibers drawn from Suprasil II. The surface features of the birefringent fibers were compared to a model of the residual axial stress profile resulting from a diffusion‐controlled surface stress relaxation. Additionally, a uniform birefringence in the fiber equivalent to a constant tensile stress was recognized and attributed to structural anisotropy produced during fiber drawing. The contribution of structural anisotropy to the observed birefringence remained constant as the surface features were successively etched away. Surface compressive stress generation was also observed, as retardance corresponding to a surface compressive stress was found to increase with applied tensile stress during short heat treatments. Significant features of the retardance profile in as‐received silica glass fibers, with a thin surface compressive stress layer and compensating interior tensile stress, agreed with the residual stress profiles predicted by the surface stress relaxation model after correcting for this observed structural anisotropy.

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“…Earlier, it was shown that surface stress relaxation can be used to make stronger glass fibers [23][24][25] and is also the source of surface compressive stress degradation of ion-exchange strengthened glasses. Earlier, it was shown that surface stress relaxation can be used to make stronger glass fibers [23][24][25] and is also the source of surface compressive stress degradation of ion-exchange strengthened glasses.…”

Section: Discussionmentioning

confidence: 99%

“…[18][19][20][21] When an applied uniaxial tensile stress relaxes at a specimen surface, the surface acquires a compressive stress upon release of the applied load. 18 Surface stress relaxation has been used to produce high strength glass fibers by formation of a surface compressive stress [23][24][25] and also to model the degradation of the surface compressive stress generated by the ion-exchange process. Thus, the acquired residual compressive stress has been shown to reach GPa range 22 if the applied tensile stress is also at this range.…”

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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Strengthening of E-glass fibers by surface stress relaxation

Cited by 20 publications

References 22 publications

Determining the mechanism controlling glass fibre strength loss during thermal recycling of waste composites

Determining the mechanism controlling glass fibre strength loss during thermal recycling of waste composites

Modeling birefringence in SiO₂ glass fiber using surface stress relaxation

Origin of the Static Fatigue Limit in Oxide Glasses

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Strengthening of E-glass fibers by surface stress relaxation

Cited by 20 publications

References 22 publications

Determining the mechanism controlling glass fibre strength loss during thermal recycling of waste composites

Determining the mechanism controlling glass fibre strength loss during thermal recycling of waste composites

Modeling birefringence in SiO2 glass fiber using surface stress relaxation

Origin of the Static Fatigue Limit in Oxide Glasses

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Modeling birefringence in SiO₂ glass fiber using surface stress relaxation