keywords: Multi-physical parameter point sensing, distributed FBG sensors, distributed FOS
This research work presents the development of fibre Bragg grating sensor model for simultaneous monitory of strain, stress and applied load on composite structures. The deployment of composite structures in harsh environment makes Structural Health Monitoring (SHM) system of great important. Point sensing is a process whereby a sensor senses physical parameter on a specific spot on the composite structure in which they are deployed. Most point sensors sense only one physical parameter which is subject to the nature of their encapsulation. Point sensors are generally classified into two broad areas they are the interferometric and the FBG sensors. In the distributed sensing the length of the fibre is the sensor or an array of sensor is inscribed in the length of the optical fibre. Distributed sensing is classified into Distributed Optical Fibre Sensor (DOFS) and Distributed Fibre Bragg Grating Sensor (DFBGS). In this work, with the aid of relationship model the measuring capacity of FBG point sensor is extended to simultaneously compute the values of strain, stress and load. By accounting for strain values and extending it to obtaining stress and applied load components on the structure, respectively. This in turn reduces the number of sensors deployed during monitoring, there for reducing cost of deployment and network complexity without depleting the sensors efficiency. Furthermore, the shift in Bragg wavelength for the enhanced FBG (iFBG) was plotted against that of the conventional FBG (FBG). The graphs show that the shift in Bragg wavelength for the enhanced FBG sensitivity is higher than that of the conventional FBG. It is due to the increase in Poisson’s ratio and decrease in effective refractive index of the FBG sensor.