Richard Hartford Norris

Bend insensitive fibers for FTTH and MDU

As deployment of fiber to the home (FTTH) within multiple dwelling units (MDUs) is growing, more technicians will be involved in the deployment of optical drop cables, and there is a desire to use craft and practice similar to what is used for copper cables. We introduce a solid bend insensitive fiber in this application that is backwards compatible to G.652D fiber, and has macrobending, splice loss and system performance to meet the very demanding conditions of these applications. A closer look at the demands of this environment has made it necessary to re-evaluate reliability in these critical applications. We apply the Power Law Model to predict reliability in these demanding applications, and provide experimental evaluation of the model through testing on optical fibers and cables. It will be shown that bends and tension need to be considered together when evaluating the reliability of the passive optical plant.

Elevated temperature deformation and crack growth behavior in titanium alloy 6-2222

Abstract Elevated temperature tests were performed on titanium alloy 6-2222 (Ti 6-2222) sheet material to determine the creep deformation behavior and to evaluate the suitability of crack tip parameters for characterizing creep crack growth behavior in the temperature range of 350–450°C. At temperatures of 400°C and above, the material behaves essentially as a creep-ductile material in which the creep crack growth rate is characterized by the Ct parameter. At 350°C, transition from creep-ductile to creep-brittle behavior was observed. A correlation which is independent of temperature for creep-ductile conditions in the range of 350–450°C between creep crack growth rate and Ct is derived from these tests. The creep-brittle behavior observed at 350°C was in the transient range where no well-accepted crack tip parameter is available for characterizing the crack growth behavior. A methodology for predicting creep crack growth in Ti 6-2222 sheet structures at elevated temperature when creep-ductile behavior is observed is briefly discussed.