Experimental and Numerical Analysis on Influence of Embedded Optical Fibre on Advanced Composites of Structural Health Monitoring of Passenger Car 2014-28-0011

The influence of embedded optical fibre on the strength and stiffness of flexurally loaded composite laminate is studied in this paper. In a given structure, different loads create a complex state of stresses in the structure. In-situ structural health monitoring of composite structures could be achieved by using embedded optical fiber as sensors. Modern OFS (Optical Fibre Sensors) are suitable for the measurement of temperature, pressure, strain, angular rotation, speed, acceleration, curvature, flow, refractive index, and many other parameters. The strength and fracture behaviour of the structure could be significantly affected by improper alignment and placement of optical fibres in the laminate. The utilization of embedded optical fibres for damage detection is accurate and reliable if the interaction between the optical fibre and the delamination is known. Despite their small size, compared to the typical diameter of the reinforcement fibres, the diameter of optical fibre is large enough to induce stress concentrations and geometric discontinuities in the structure.

The primary goal of this research is to assess whether the inclusion on optical fibre creates a local stress concentration which could trigger delamination and final collapse of the structure. In the current study optical fibres are embedded in three types of specimens; first at the neutral axis (50% thickness) and second at 75% thickness from the mould surface and at last without optical fibre. Glass Fibre Laminate specimens are manufactured with adequate post-curing. The resin rich area is around the optical fibre and the bonding between the optical fibre and the resin is studied using Scanning Electron Microscope (SEM). An attempt is made to assess the structure using C-Scan method. It was concluded that the embedded optical fibers could be successfully used as sensors in composite laminate and will not significantly compromise the strength and integrity of the composite host.