Temperature Dependence of Static Fatigue of Optical Fibers Coated with a Uv‐Curable Polyurethane Acrylate

Chandan, Harish C.; Kalish, David

doi:10.1111/j.1151-2916.1982.tb10389.x

Cited by 49 publications

(16 citation statements)

References 6 publications

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“…Other observations were similar to these, or reported the increased ratio of observed velocities as a function of increased temperature . Supporting evidence for thermally activated increases in crack velocity with temperature in fused silica is provided by decreased failure times in the constant stress failure data of Figure C 35 and earlier and decreased strengths in constant stressing rate data …”

Section: Crack Propagation Parameterssupporting

confidence: 75%

Thermal activation effects in crack propagation and reliability of fused silica

Cook

2019

J Am Ceram Soc

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The thermal activation energy u1 characterizing changes in crack velocity with temperature for fused silica in water is determined. The determination is based on a new analysis that incorporates the familiar Arrhenius term for thermally activated processes and a term characterizing the departure of the propagating crack system from fracture equilibrium. In determining u1 from experimental data, the Arrhenius term and the nonequilibrium term are of approximately equal magnitude. The analysis is applied to an extensive compilation of crack velocity measurements in fused silica to arrive at an estimate of u1 = (69 ± 11) kJ mol−1, where the value represents the multi‐laboratory mean ± variability. This value is greater than that assumed in some earlier works and characterizes a typical within‐laboratory increase in crack velocity of a factor of approximately 102 in fused silica between freezing and boiling water conditions and a decrease of a factor of 103 in component time to failure for the same change in conditions. The multi‐laboratory variation in velocity at fixed temperature is comparable to the within‐laboratory maximum increase, perhaps obscuring temperature effects.

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Section: Crack Propagation Parameterssupporting

confidence: 75%

Thermal activation effects in crack propagation and reliability of fused silica

Cook

2019

J Am Ceram Soc

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“…It is evident that the crack propagation velocity should change after intersection of the phase boundary. Consequently, the linear dependence of the logarithm of the durability on the logarithm of the tensile stress for the silica fiber in the range of small loads should exhibit a kink [10]. For large breaking loads, the depth of the critical crack is comparable to the size of microinhomogeneity region containing the impurity, which more easily interacts with water as compared to silicon dioxide.…”

Section: Resultsmentioning

confidence: 96%

Influence of the physicochemical state of impurities on the strength of silica fibers

et al. 2006

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The size distribution of compositional microinhomogeneities in silica glasses prepared by different methods is investigated by electron microscopy. The formation of these defects is caused by the presence of impurities introduced into the glass upon phase separation and segregation. The surface of millimeter-sized segments of silica optical fibers 125 µ m in diameter always contains inhomogeneities up to 1 µ m in size. This explains the growth of cracks to a critical size in microregions containing impurities in the course of strength tests of glass fibers.

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“…(4) relates the strength, a, to the loading rate, do/dt (dynamic fatigue). It is noted that dynamic fatigue experiments can be used to determine the unknown parameters in Eq.…”

Section: Infroductionmentioning

confidence: 99%

<title>Ionic effects on silica optical fiber strength and models for fatigue</title>

Rondinella

Matthewson

1991

SPIE Proceedings

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The strength and fatigue behavior of bulk fused silica is well understood in terms of the growth of microcracks under the combined influence of stress and environmental attack. The behavior of high strength, flaw free silica optical fiber shows significant differences from the bulk material for poorly understood reasons making long term predictions unreliable. It is known that silica fiber strength and fatigue are sensitive to such environmental parameters as temperature, humidity and pH. However, this paper presents results which also show a sensitivity to ionic species in the environment. These results are interpreted in terms of possible models for the fiber behavior. INFRODUCTIONIn most ceramic materials and, in particular, in oxide glasses, failure can occur after prolonged application of a constant stress which is significantly lower than the stress required to cause catastrophic failure on a short time scale. This phenomenon, called fatigue or delayed failure, can determine the long term reliability of ceramic components. A complete understanding of the mechanisms that produce delayed failure would allow one to make reliable lifetime predictions for components (in our case, optical fiber) under operating conditions.The mechanism that causes fatigue in most ceramic materials consists of slow growth of pre-existing cracks up to the critical size for fast crack growth. The slow growth is due to stress-enhanced environmental attack of the strained bonds at the crack tip. The empirical relationship between the rate of growth of a macroscopic crack, dc/dt, and the applied stress intensity factor, Kj, may be described by a power 1 = AK1.( 1) where n is the stress corrosion susceptibility parameter. By combining it with the Griffith relation, K1 = aYc1'2 , (2) and integrating, two equations can be obtained:relates the time to failure, tj, to a constant applied stress, oa, (static fatigue) while on+1 = 2&[a]fl2. (4) relates the strength, a, to the loading rate, do/dt (dynamic fatigue). It is noted that dynamic fatigue experiments can be used to determine the unknown parameters in Eq. (3) and hence predict time to failure under static conditions.The slow crack growth model provides a good explanation of fatigue behavior for crack containing bulk glass. By considering the published data for high strength silica fiber, however, some discrepancies are noted. The value of n derived from Eq. (3) and (4) for weak, bulk silica is around 40, in good agreement with crack velocity measurements made

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Temperature Dependence of Static Fatigue of Optical Fibers Coated with a Uv‐Curable Polyurethane Acrylate

Cited by 49 publications

References 6 publications

Thermal activation effects in crack propagation and reliability of fused silica

Thermal activation effects in crack propagation and reliability of fused silica

Influence of the physicochemical state of impurities on the strength of silica fibers

<title>Ionic effects on silica optical fiber strength and models for fatigue</title>

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