Feasibility of integrated optical fibre sensors for condition monitoring of composite structures Part Ⅱ: Combination of Bragg-sensors and acoustic emission detection

摘要

This paper discusses the possibility of continuously monitoring the mechanical behaviour of composite structures by means of optical fibre sensors. In the first paper some basic principles of optical fibre sensors in general and Bragg-sensors in particular have been briefly reported. Experimental results showed that optical fibre Bragg-sensors are much more reliable compared to traditionally used electrical-resistance strain gauges. In the introduction to this second paper, the discussion is extended to the broader context of condition monitoring. Filament wound pressure vessels have again been used as a representative composite structure. Instrumentation of the vessel consisted of an embedded Bragg-sensor, an acoustic emission detector and a pressure transducer. The results of a burst pressure experiment are discussed in this second paper. In this 'fully monitored' experiment, Bragg-sensors are used for strain monitoring and damage is monitored through acoustic emission detection. With additional research effort, and provided that adequate tools for the simulation of a degrading fibre-reinforced structure become available, permanent condition monitoring of critical structures can become realistic in the near future. The Bragg-senssor type can be considered a key instrument for monitoring applications of composite structures, provided that they become available at economically interesting prices.