Fiber-optic sensor design for chemical process and environmental monitoring

Mahendran, Ramani S.; Wang, Liwei; Machavaram, Venkata R.; Pandita, Surya D.; Chen, Ruirun; Kukureka, Stephen N.; Fernando, Gerard Franklyn

doi:10.1016/j.optlaseng.2009.05.013

Cited by 28 publications

(16 citation statements)

References 24 publications

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“…However the silica treatment was found to affect the curing kinetics; higher curing rates but lower conversion of epoxy functional groups was observed with the increase of silane concentration. Mahendran et al [49] developed transmission mode OFS which were embedded in thermoset resins and used for cure monitoring. Simple fixtures kept the transmitting and receiving end of the optical fiber in position and infrared spectra was acquired periodically throughout conversion at various temperatures.…”

Section: Spectrometersmentioning

confidence: 99%

Monitoring the production of FRP composites: A review of in-line sensing methods

Konstantopoulos¹,

Fauster²,

Schledjewski³

2014

Express Polym. Lett.

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Abstract.Composites manufacturing is characterized by many degrees of freedom. Different materials, geometries and thermo-dynamical conditions contribute to a behavior that is difficult to predict. Monitoring the running process (in-line monitoring) eliminates the need for prediction; real time data provided by appropriate sensing systems can be used in the direction of process optimization, quality upgrade or material characterization. The aim of the review at hand is to record and discuss the latest progress in the field of in-line composites monitoring with a focus on Fiber Reinforced Polymericbased (FRP) composite structures. Summaries of each sensor's principles of operation, appropriate association with polymer/composite properties detection, brief descriptions of representative studies, a critical overview of implementation aspects and discussion on the upcoming trends, contribute in constructing a complete picture.

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Section: Spectrometersmentioning

confidence: 99%

Monitoring the production of FRP composites: A review of in-line sensing methods

Konstantopoulos¹,

Fauster²,

Schledjewski³

2014

Express Polym. Lett.

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“…From reaction schemes-1 and 2, the increase in the concentration of the OH functional group as a consequence of the cross-linking reaction can also be monitored to estimate the crosslinking kinetics [2].…”

Section: Introductionmentioning

confidence: 99%

“…The ring-opening cross-linking reactions shown in Fig. 1 are exothermic and hence it is necessary to monitor and manage the thermal gradients within the preform during processing [2]. In general, laboratory-based processing equipment have a facility for heating and cooling to enable isothermal conditions to be maintained; this is necessary to obtain repeatable and reliable cross-linking kinetic data.…”

Section: Introductionmentioning

confidence: 99%

Process monitoring of fibre reinforced composites using a multi-measurand fibre-optic sensor

Nair

Machavaram

Mahendran

et al. 2015

Sensors and Actuators B: Chemical

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a b s t r a c tThis paper reports on the design, fabrication, characterisation and deployment of a multi-measurand optical fibre sensor (MMS) that is capable of simultaneously monitoring strain, temperature, refractive index and cross-linking chemistry. The sensor design is based on the extrinsic fibre Fabry-Perot interferometer. A feature of this sensor system is that a conventional multi-channel fibre-coupled near-infrared spectrometer is used to monitor the four independent parameters. The issues relating to the measurement resolution of the individual sensors and the associated interrogation equipment are discussed. The MMS was embedded in between the fourth and fifth plies of an eight-ply E-glass plain-weave fabric. A commercially available thermosetting epoxy/amine resin system was used to impregnate the fabric layers manually. The laminated preform was vacuum-bagged and cured in an autoclave. The following parameters were monitored: the depletion rates of the epoxy and amine functional groups in the resin system; the temperature in close proximity to the "chemical sensor"; the evolution of strain; and the refractive index of the resin system. The effect of post-processing on the output from the embedded optical fibre sensors is also considered.

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“…Giordano et al demonstrated an optical fiber sensing system for the simultaneous measurement of refractive index via Fresnel reflection, and strain via a fiber Bragg grating . More recently, Mahendran et al demonstrated a multifunctional sensor system where a conventional fiber‐coupled FTIR near‐infrared spectrometer was used to monitor four independent parameters simultaneously: strain, temperature, refractive index, and cross‐linking kinetics of an epoxy/amine resin system . Fiber‐optic Fresnel sensors have also been used for cure monitoring of thermoset resins containing fillers and during resin infusion …”

Section: Introductionmentioning

confidence: 99%

Multi‐point monitoring of cross‐linking reactions

Machavaram

Wang

Pandita

et al. 2014

J of Applied Polymer Sci

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The feasibility of deploying optical fiber sensors to obtain qualitative and quantitative information on the cross-linking characteristics of thermosetting resin systems has been demonstrated by a number of researchers. This article is concerned with the demonstration of a low-cost fiber-optic Fresnel sensor system for monitoring the cross-linking reactions at multiple locations. Crosslinking reactions can be influenced by a number of parameters including the stoichiometry of the resin and hardener, and the heattransfer rates in and out of the preform as a function of the cross-section of the preform. In situations where there is a variation in the thickness of the preform or when large components are processed, a facility to monitor the cross-linking reactions at multiple locations will be valuable because the rate and extent of the cross-linking can be inferred. In this article, six Fresnel sensors were immersed in individual vials containing an epoxy/amine resin system and processed (cross-linked) in an air-circulating oven. One additional vial with a Fresnel sensor immersed in the neat epoxy resin (no hardener) was co-located in the oven to enable the effect of temperature to be monitored. The feasibility of using the multiplexed Fresnel sensors for cure monitoring was demonstrated successfully. The sensors in the post-cross-linked samples were used to study the effects of heating and cooling cycles. The feasibility of detecting the glass transition temperature using the Fresnel sensor is discussed along with the factors that give rise to variability in the output Fresnel signals.

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Fiber-optic sensor design for chemical process and environmental monitoring

Cited by 28 publications

References 24 publications

Monitoring the production of FRP composites: A review of in-line sensing methods

Monitoring the production of FRP composites: A review of in-line sensing methods

Process monitoring of fibre reinforced composites using a multi-measurand fibre-optic sensor

Multi‐point monitoring of cross‐linking reactions

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