Self-sensing hybrid composite rod with braided reinforcement for strutural health monitoring

摘要

Enhancing the performance and lightness of different structures has already beenachieved by the employment of fibre reinforced composite materials. Nowadays, a new challengingperspective is being given to these materials by the inclusion of non-metallic conductivecomponents. This emerging technology will lead to multifunctional composites with possibleapplications in structural health monitoring and traffic monitoring. The aim is to avoid corrosionproblems from metallic components, as well as to eliminate the need of expensive equipments usedfor the health monitoring of large infrastructures.In the present research, the strain-sensing capability of a core-reinforced hybrid carbon fibre/glassfibre braided composite has been investigated in order to develop continuous monitoring system.The characterization of sensing behaviour was performed with the help of an instrumental set-upcapable of measuring the change in electrical resistance with mechanical stresses applied to thesamples. The effect of core composition (carbon fibre/glass fibre weight ratio) on the strainsensitivity of the braided composites has been studied in order to find out the optimum compositionfor best sensing capability. Among the three compositions studied (23/77, 47/53 and 100/0),composites with lowest amount of carbon fibre showed the best strain sensitivity with gauge factorsup to 23.4 at very low flexural strain (0.55%). Attempts have also been made in this research todevelop a piezoresistive matrix for the braided composites in order to further enhance their strainsensitivity. For this purpose, the strain sensing capability of an unsaturated polyester matrixdispersed with chopped carbon fibres (1mm and 3 mm lengths) at various weight % (0.5, 0.75 and1.25%) was evaluated in order to find out their optimum length and concentration. It was observedthat chopped fibres with different lengths showed similar strain sensitivity, which however,improves with the decrease in their concentrations.