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

Konstantopoulos, Spyridon; Fauster, Ewald; Schledjewski, Ralf

doi:10.3144/expresspolymlett.2014.84

Cited by 85 publications

(57 citation statements)

References 75 publications

(77 reference statements)

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“…A range of optical techniques have been investigated for composite material processing, with demonstrations of the ability to detect the presence of resin using a single sensor [20,21], to measure resin flow during the infusion when the sensors are spatially multiplexed [14,22], and to monitor the cure of the resin [11,21,22]. Superimposed fibre grating sensors, offering strain-temperature discrimination, have also been demonstrated for cure monitoring [23].…”

Section: Ultrasonic Sensorsmentioning

confidence: 99%

Resin Directional Flow and Degree of Cure Sensing Using Chirped Optical Fiber Long Period Gratings

et al. 2017

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The use of chirped long period gratings (CLPGs) for monitoring the flow, the direction of the flow and the subsequent cure of an epoxy resin is presented. The asymmetric properties of the CLPG and its sensitivity to refractive index changes were exploited to facilitate the measurement of the direction of the flow. The performances of a continuously chirped LPG (CCLPG) and a step chirped LPG (SCLPG) were compared, with the CCLPG showing improved spatial resolution. The CCLPG and SCLPG were also used to monitor changes in the refractive index of the resin during cure, with the results showing close agreement with measurements undertaken simultaneously using a fibre optic Fresnel refractometer.

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Section: Ultrasonic Sensorsmentioning

confidence: 99%

Resin Directional Flow and Degree of Cure Sensing Using Chirped Optical Fiber Long Period Gratings

et al. 2017

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“…The tool supports heating by liquid that flows through heating channels opened in the tool body while it was designed to host different sensors, namely dielectric analyzer, direct current sensor, ultrasound sensor, and pressure transducers. All of the above detect (among other quantities) flow 17 but technical…”

Section: Computational Aspectsmentioning

confidence: 99%

Identification of the effect of typical curvatures encountered in RTM parts on localized permeability of fibrous preforms

Konstantopoulos

Hueber

Mühlbachler

et al. 2016

Advanced Manufacturing: Polymer & Composites Science

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Filling is a critical stage in resin transfer molding (RTM) manufacturing; it is associated to the formation of impregnation imperfections which can lead to defects. Simulations are typically employed to predict the flow behavior, which however need the preform permeability as an input. Significant work has been done in the past in in-plane permeability identification. This study focuses on the determination of the permeability of unidirectional curvatures typically encountered in RTM parts. A model for analytical calculation and a numerical optimization approach for inverse determination have been developed and applied in an omega-shaped RTM part where material-embedded flow sensors were employed for the essential flow measurements. The differences found between the experimentally derived permeability of the curvature and theoretical predictions were discussed critically and associated to flow time disagreements between simulations and reality.

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“…Therefore, the use of real‐time in‐mold sensors to monitor the material behavior and process conditions have continuously been a research topic over the last years . Dielectric analysis (DEA) has been evaluated as the technology with the greatest potential for in‐situ material characterization during the cure of an epoxy resin . Previous studies also showed that phase transitions of a two‐step‐curing polyurethane resin for pultrusion processing and of carbon fiber‐reinforced thermoplastic materials can be distinguished by DEA .…”

Section: Introductionmentioning

confidence: 99%

Dielectric and rheological study of the molecular dynamics during the cure of an epoxy resin

Chaloupka

Pflock²,

Horny

et al. 2018

J Polym Sci B Polym Phys

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Composite manufacturing is currently one of the most challenging processes for industrial lightweight applications. To date, the process conditions for polymer-based composite manufacturing are evaluated by laboratory measurements: usually, the flow behavior and the curing of the polymer matrix material are characterized by rheology and quality assurance is performed by thermo-physical analysis in postprocess measurements. In contrast a dielectric in-mold sensor offers the possibility to measure the real-time behavior of the polymer during processing. This study focuses on the correlation of simultaneous rheological and dielectric measurements on Hexcel RTM6 using a coupled setup of both techniques. For dielectric measurements a reusable in-mold sensor was used and a calibration, taking into account the cable response, was performed. The results show good agreement with respect to glass-transition temperature and the gel-point. This can be understood by the fluctuation-dissipation theorem that explicitly relates molecular dynamics to the macromolecular mechanical properties under dynamic time-dependent load. Furthermore, it was found that the dynamic viscosity can directly be related to the electrical conductivity. This proves the high potential of dielectric analysis as online-capable technique for material characterization during composite manufacturing. V C 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 907-913

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

Cited by 85 publications

References 75 publications

Resin Directional Flow and Degree of Cure Sensing Using Chirped Optical Fiber Long Period Gratings

Resin Directional Flow and Degree of Cure Sensing Using Chirped Optical Fiber Long Period Gratings

Identification of the effect of typical curvatures encountered in RTM parts on localized permeability of fibrous preforms

Dielectric and rheological study of the molecular dynamics during the cure of an epoxy resin

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