| The research presented here is concerned with the development of mathematical models for optical fibers drawing process. Optical fibers are made from glass rods called preforms, which are initially about two meters long and five to nine centimeters in diameter. The preform is fed into a cylindrical furnace, heated to its softening temperature, and then pulled downward to form a fiber. The diameter of the fiber is about 125 μm.; During the drawing process, the fiber diameter may exhibit significant fluctuations. Such fluctuations result from several factors such as furnace temperature variation, longitudinal variation of the preform diameter, preform feeding rate, fiber draw speed, ambient gas flow instabilities in the furnace, and/or mechanical vibration of the drawing machine. These factors may also affect the fiber tensile strength. To obtain high quality fibers, it is necessary to design a feedback control system for the drawing process. Optimization of such a control system requires identification of the distributed nonlinear drawing process and a quantification of the sensitivities of the process to both disturbances and changes in process parameters.; In this research, a systematic approach to modeling optical fibers drawing process is presented. First, a fluid dynamic model of the drawing process that, serves as a simulation tool is developed. Then, numerical methods are devised to perform numerical simulations of the drawing process. From these numerical simulations, steady state operating conditions of the drawing process, such as velocity and temperature profiles, are obtained. These operating points are in turn used to build state space models suitable for modern feedback control design. The research presented here is intended to improve the overall performance of existing optical fiber drawing processes by providing mathematical models and simulation tools for the drawing process. |
