Optimisation of Optical Fibres for Structural Health Monitoring Through Micro-braiding

Abstract

Structural health monitoring (SHM) of composite structures has become paramount in aerospace industry in recent years. With advances in research and innovation, this can be achieved in real time by embedding optical fibre into the structure to be monitored. The optical fibre has been proven to be versatile for application in SHM due to its ability to measure strain and temperature. However, the optical fibres are brittle which makes their handling and integration difficult. This issue can be solved by micro-braiding the optical fibre, with the judicious type of reinforced fibre. Braiding is a textile forming (both tubular and flat) technique that is capable of producing near net shaped structures, in which the tow such as glass fibre can be interlaced at bias angle (braid angle). This paper presents the optimised material selection, fibre orientation and machine speed. Variation in braid angle is achieved by varying the take up speed while keeping the braider machine speed constant. The tensile properties of the conventional and micro-braided optical fibre are presented and compared. The improvement of tensile strength and strain is observed and discussed.