Article

The combined effect of temperature and humidity on the fatigue parameters and reliability of optical fiber

Proc SPIE 09/2004; DOI: 10.1117/12.582546

ABSTRACT The lifetime of an optical fiber depends on its environment. Previous work extensively measured and characterized the separate effects of humidity and temperature on the fatigue parameters using three different kinetics models, but the combined effect has not been determined in detail. In this work, the details of how the fatigue parameters vary with temperature in a humid environment were investigated. It was found that the kinetics model parameters were different from values obtained elsewhere in liquid water. This may be the result of differences in the apparent activation energy for fatigue in liquid and vapor environments.

0 Bookmarks
 · 
84 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Stress corrosion cracking of six glasses was studied using fracture mechanics techniques. Crack velocities in water were measured as a function of applied stress intensity factor and temperature, and apparent activation energies for crack motion were obtained. Data were consistent with the universal fatigue curve for static fatigue of glass, which depended on glass composition. Of the glasses tested, silica glass was most resistant to static fatigue, followed by the low-alkali aluminosilicate and borosilicate glasses. Sodium was detrimental to stress corrosion resistance. The crack velocity data could be explained by the Charles and Hillig theory of stress corrosion. It is probable that stress corrosion of glass is normally caused and controlled by a chemical reaction between the glass and water.
    Journal of the American Ceramic Society 09/1970; 53(10):543 - 548. · 2.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Subcritical crack growth in fused silica is treated as a stress assisted chemical reaction between water and strained bonds at the crack tip. In this work, the kinetics of the reaction is modeled by assuming the stress reduces the energy barrier of the activated complex by affecting both the activation enthalpy and entropy, where the stress dependence can take different forms. This theory is compared with dynamic fatigue data obtained for pristine fused silica optical fiber. The experiments were conducted in both distilled water and pH 7 buffer solution, and the results are found to be similar. The fatigue parameters were found by fitting to three different forms for the stress dependence; the activation enthalpy and entropy were then determined from the fatigue parameters. It is found that stress increases the activation entropy, whichever kinetic form is used, and thereby reduces the activation energy barrier height. The activation enthalpy is also stress dependent, but stress tends to increase the enthalpy contribution to the barrier height. The results show subcritical crack growth in high strength silica is dominated by entropy effects. © 2001 American Institute of Physics.
    Journal of Applied Physics 05/2001; · 2.21 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: There have been numerous studies of the fatigue and strength behavior of fused silica optical fibers. However, no coherent model has emerged that self-consistently describes the simultaneous effects of stress, temperature and activity of the corroding species (e.g. water). A power law degradation kinetics model (relating the crack growth rate to the applied stress intensity factor, K I) is widely used although various exponential forms based on chemical rate theory have also been proposed. The dependence of fatigue on parameters such as humidity, pH and temperature, has usually been treated in an empirical manner. Sometimes it is even ignored -for example, the service environment is often assumed to be the same as the proof test environment when making lifetime predictions, thus avoiding the need for understanding the humidity dependence; this assumption is often unjustified. This paper reviews the dependence of fatigue on environmental factors and highlights some of the inconsistencies in published data. It is then attempted to present a coherent kinetics model that simultaneously accounts for stress temperature, humidity, etc. Several possible forms of the model are compared to a range of experimental data of several different types. The comparison is made using fitting techniques that account for correlation between fit parameters. It is found that a simple exponential form of the degradation kinetics model gives the best overall description of the temperature, humidity and pH effects on static and dynamic fatigue. It should be noted that the exponential form predicts shorter lifetimes than the ubiquitous power law model. Therefore, under some circumstances, the predictions of "worst case" models based on power law kinetics are unduly optimistic.

Full-text (2 Sources)

View
109 Downloads
Available from
May 19, 2014