Development of Hybrid Braided Composite Rods for Reinforcement and Health Monitoring of Structures

Sohel Rana,Emilija Zdraveva,Cristiana Pereira,A Gomes Correia,Raul Fangueiro

doi:10.1155/2014/170187

Abstract

In the present study, core-reinforced braided composite rods (BCRs) were developed and characterized for strain sensing capability. A mixture of carbon and glass fibre was used in the core, which was surrounded by a braided cover of polyester fibres. Three compositions of core with different carbon fibre/glass fibre weight ratios (23/77, 47/53, and 100/0) were studied to find out the optimum composition for both strain sensitivity and mechanical performance. The influence of carbon fibre positioning in BCR cross-section on the strain sensing behaviour was also investigated. Strain sensing property of BCRs was characterized by measuring the change in electrical resistance with flexural strain. It was observed that BCRs exhibited increase (positive response) or decrease (negative response) in electrical resistance depending on carbon fibre positioning. The BCR with lowest amount of carbon fibre was found to give the best strain sensitivity as well as the highest tensile strength and breaking extension. The developed BCRs showed reversible strain sensing behaviour under cyclic flexural loading with a maximum gauge factor of 23.4 at very low strain level (0.55%). Concrete beams reinforced with the optimum BCR (23/77) also exhibited strain sensing under cyclic flexural strain, although the piezoresistive behaviour in this case was irreversible.

Highlights

Light weight combined with very good mechanical properties has opened up the possibility of using fibre reinforced plastics (FRPs) in several high end applications including reinforcement of concrete structures
It can be noticed that the highest strain sensitivity or gauge factor was obtained with BCR1 and the strain sensitivity decreased with the increase in carbon fibre percentage in the braided composite rods (BCRs) composition
This paper reported the potential of core-reinforced hybrid carbon fibre/glass fibre braided rods for continuous monitoring of very low flexural strain

Summary

Introduction

Light weight combined with very good mechanical properties has opened up the possibility of using fibre reinforced plastics (FRPs) in several high end applications including reinforcement of concrete structures. The approach of inserting various types of sensor (strain gauges, piezoelectrics [1, 2], fibre optics [3, 4], etc.) into the structures for health monitoring is usually complex and expensive and requires highly skilled personnel for their application and use. These problems can be overcome by turning concrete structures intelligent, that is capable of sensing their own deformation and damage. Use of hybrid composites containing mixture of conductive reinforcements with other reinforcements such as glass and aramid proved helpful to introduce pseudoductility in order to detect

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Conclusion