The authors have demonstrated previously that reinforcing glass fibres can be used as light-guides to facilitate chemical
process monitoring and structural integrity assessment of fibre reinforced composites. In the current paper, the authors
explore concepts for the development of self-sensing, self-healing and crack-arrestor composites.
The first part of the papers presents a brief overview of previously reported technologies for self-sensing, self-healing
and crack-arrestor; the advantages and disadvantages of the various technologies are discussed. The second part of this
paper present the design concept and performance requirements for the self-sensing, self-healing and crack-arrestor
composites. The final part of the paper presents preliminary results on the manufacture and evaluation of this class of
Fibre Bragg grating (FBG) sensors continue to be used extensively for monitoring strain and temperature in and on
engineering materials and structures. Previous researchers have also developed analytical models to predict the loadtransfer
characteristics of FBG sensors as a function of applied strain. The general properties of the coating or adhesive
that is used to surface-bond the FBG sensor to the substrate has also been modelled using finite element analysis.
In this current paper, a technique was developed to surface-mount FBG sensors with a known volume and thickness of
adhesive. The substrates used were aluminium dog-bone tensile test specimens. The FBG sensors were tensile tested in
a series of ramp-hold sequences until failure. The reflected FBG spectra were recorded using a commercial instrument.
Finite element analysis was performed to model the response of the surface-mounted FBG sensors. In the first instance,
the effect of the mechanical properties of the adhesive and substrate were modelled. This was followed by modelling the
volume of adhesive used to bond the FBG sensor to the substrate. Finally, the predicted values obtained via finite
element modelling were correlated to the experimental results. In addition to the FBG sensors, the tensile test specimens
were instrumented with surface-mounted electrical resistance strain gauges.
Significant progress has been made in recent years on the design and deployment of optical fibre-based sensors to
monitor the cross-linking (cure) reactions in thermosetting resins. In the current study, the following sensor designs
were used to study cross-linking reactions of an epoxy/amine resin system: (i) intensity-based Fresnel sensors, (ii)
extrinsic fibre Fabry-Perot interferometic (EFPI) sensors, (iii) fibre Bragg grating (FBG) sensors and (iv) sensor designs
to enable transmission, reflection and evanescent wave spectroscopy.
This paper presents a detailed study on a comparison of the above-mentioned techniques for a commercially available
epoxy/amine resin system. Conventional Fourier transform infrared spectroscopy was used as the reference method for
obtaining quantitative data on the cross-linking kinetics. The shrinkage of the resin during cross-linking was monitored
using EFPI and FBG sensors. This paper also discusses the cross-linking data obtained using optical fibre-based
evanescent wave spectroscopy.
The focus of this paper is on real-time damage detection in reinforcing fiber bundles and composites using high-speed
photography and image analysis. In other words, the end of a reinforcing fiber bundle or composite is imaged and the
sequence of fiber fracture is monitored using a high-speed camera. These studies were undertaken using as-received and
silane-treated custom-made optical fibers of around 12 μm diameter and E-glass fibers of 15 (±3) μm diameter.
The first part of this paper reports on the techniques that were developed to produce void-free test specimens and the
procedures used for imaging the end of the fiber bundle and composite during tensile loading. Evanescent wave
spectroscopy was used to study the effect of silane treatment on the cross-linking kinetics of an epoxy/amine resin
system. Conventional piezo-electric acoustic emission (AE) transducers were used to monitor the acoustic events
occurring during the tensile test. The signals from the AE transducers were used to trigger the high-speed camera.
The second part of this paper presents details of the image analysis routines that were developed to track the light
intensity transmitted through individual fibers during tensile loading. Good correlation was observed between the
transmitted light intensity and the AE signals.
The degradation mechanism of ionic polymer metal composites (IPMCs) containing hydrophobic ionic liquids has been investigated. The ionic liquid was mixed with ethylene glycol in order to obtain high solvent uptake. The actuation response of the IPMCs with the mixed solvent was faster than that with only ethylene glycol. During the actuation durability tests under an AC square wave input, the IPMCs suffered from liquid squeezing-out problem, resulting in lower solvent concentration inside the IPMCs and hence poor actuation response. The degradation development of the IPMCs was influenced by the applied AC frequency. The tip displacement and the electric current were used to study the degradation development under AC electric field. Tin layer of polyurethane was applied on the IPMC surface to minimize the squeezing problems. The degradation was not significant observed after being subjected to 3V square wave input for more than 20 hours. However, the conductivity of the coated IPMCs was lower than that of the uncoated ones.
Manufacturing and characterization of ionic polymer metal composites (IPMCs) with silver as electrodes have been investigated. Tollen's reagent that contains ion Ag(NH<sub>3</sub>)<sub>2</sub><sup>+</sup> was used as a raw material for silver deposition on the surfaces of the polymer membrane Nafion"R". Two types of inner solvents, namely common water based electrolyte solution (LiOH 1N) and ionic liquid were used and investigated. Compared to IPMCs with platinum electrodes, silver-plated IPMCs with water electrolyte showed higher conductivity. The actuation response of silver-plated IPMCs with the water based electrolyte was faster than that of platinum IPMCs. However, the silver electrode was too brittle and severely damaged during the solvent exchange process from water to ionic liquid, resulted in high resistance and hence very low actuation behavior.