THERMOMECHANICAL INFLUENCE ON OPTICAL FIBERS DURING THE PRODUCTION AND OPERATION OF OPTICAL CABLE

Abstract

In this work the research shows that the maintenance of the mechanical integrity of optical fibers (OF) requires the determination of thermomechanical effects on OFs during the production and operation of an optical cable (OC) in order to prevent the appearance of excessive longitudinal mechanical loads on them. Generally, in the work situations are determined and analyzed in which the mechanical loads can act on optical fibers during the process of cable production and operation. It is established that due to the lower value of the thermal linear expansion coefficient (TLEC) compared with the similar parameter of optical module tube (OMT), optical fibers become considerably longer than the OMT with its contraction during cooling in production. The materials of optical module tube used in the work were polybutylene terephthalate, polyamide and polycarbonate. Calculations of the relative linear change of the OF length compared with the OMT length during its cooled showed that it significantly depends on the material of optical module tube. This causes the appearance of macrobends and may increase the value of the OF attenuation coefficient, This requires the appropriate adjustment of the speed of the sendres with the fiber coils, as well as the choice of the diameter and material of the optical module tube. On the other hand, the increase of temperature in the OC construction can lead to excessive stretching forces on the fibers which will cause the appearance of the conditions for OF rupture. This requires the consideration and creation of the necessary excess fiber length during its integration into the OMT in cable production. Research has shown that the material type of the OMT does not significantly affect on the relative linear change of the OF length compared with the length of the OC. Therefore, the way of determining the initial length of the OF in the OMT after thermal decomposition is proposed in the work, thus avoiding the appearance of excessive tensile strength.