Application of low frequency ECT method in noncontact detection and visualization of CFRP material

Cheng, Jianwei; Qiu, Jinhao; Ji, Hongli; Wang, Enrong; Takagi, Toshiyuki; Uchimoto, Tetsuya

doi:10.1016/j.compositesb.2016.11.018

Cited by 77 publications

(35 citation statements)

References 25 publications

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“…The complex current density, J(z), decays in magnitude and phase with depth such that each layer of a material will contribute differently to the real and imaginary parts of the overall magneticfield measured and thus the ECT coil impedance. The electrical anisotropy of CFRP plies leads to a non-uniform distribution of current density within cross-ply CFRP materials, as shown by Cheng et al [19] through finite-element modelling. The simulated results in Cheng et al [19] predict that the current density is a local maximum at the interface between cross-ply layers, where contact is made between orthogonal fibres.…”

Section: Ply Structurementioning

confidence: 99%

Characterisation of carbon fibre-reinforced polymer composites through radon-transform analysis of complex eddy-current data

Hughes

Drinkwater

Smith

2018

Composites Part B: Engineering

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Maintaining the correct fibre orientations and stacking sequence in carbon-fibre reinforced polymers (CFRP) during manufacture is essential for achieving the required mechanical properties of a component. This paper presents and evaluates a method for the rapid characterisation of the fibre orientations present in CFRP structures, and the differentiation of different stacking sequences, through the Radon-transform analysis of complex-valued eddy-current testing (ECT) inspection data. A high-frequency (20 MHz) eddy-current inspection system was used to obtain 2D scans of a range of CFRP samples of differing ply stacking sequences. The complex electrical impedance scan data was analysed using Radon-transform techniques to quickly and simply determine the dominant fibre orientations present in the structure. This method is compared to 2D-fast Fourier transform (2D-FFT) analysis of the same data and shown to give superior quantitative results with comparatively fewer computational steps and corrections. Further analysis is presented demonstrating and examining a method for preserving the complex information inherent within the eddycurrent scan data during Radon-transform analysis. This investigation shows that the real and imaginary components of the ECT data encode information about the sacking sequence allowing the distinction between composites with different stacking structures. This new analysis technique could be used for in-process analysis of CFRP structures as a more accurate characterisation method, reducing the chance of costly manufacturing errors.

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Section: Ply Structurementioning

confidence: 99%

Characterisation of carbon fibre-reinforced polymer composites through radon-transform analysis of complex eddy-current data

Hughes

Drinkwater

Smith

2018

Composites Part B: Engineering

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“…The versatility of the sensor is also demonstrated with an immersion experiment. Future research will focus on optimisation of sensor geometries for specific measurement applications such as inspection of composite materials in NDT [20], [21] and multiphase flow measurements; where components with conductivity, permittivity and permeability are present. In addition, a custom instrument based on FPGA [22]- [24] will be built to replace the commercial instrument (SL 1260) to implement the measurement strategy.…”

Section: Resultsmentioning

confidence: 99%

A Novel Dual Modality Sensor With Sensitivities to Permittivity, Conductivity, and Permeability

et al. 2018

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-In this paper, an electromagnetic (EM) sensor which can operate simultaneously in capacitive and inductive modalities with sensitivities to permittivity, conductivity and permeability is developed, and a novel measurement strategy is proposed accordingly. The sensor is composed of two planar spiral coils with a track width of 4 mm, which promotes its capacitive mode. The capacitive coupling is measured in common mode while the inductive coupling is measured in differential mode. In capacitive mode, the sensor is sensitive to changes in permittivity, i.e. the dielectric material distribution; while in inductive mode, it is sensitive to magnetically permeable material and electrically conductive material. Furthermore, it is demonstrated that the sensor can simultaneously measure dielectric and conductive materials. This novel sensing element has been designed and implemented. Experimental results verified its effectiveness in dual modality measurement.

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“…Eddy current testing [15] is typically used for inspecting undulations in carbon fiber reinforcement fabrics, quality control of stacking sequence, fiber orientation and curing effects [16]. Delamination detection has been proposed [17] and shown with artificial delaminations made with interply release film [18]. Artificial cracks made by slitting the fabric before lamination have been detected [17,19,20] as well as impact damage [16,21].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Different Non-destructive Testing Methods to Detect Imperfections in Unidirectional Carbon Fiber Composite Ropes

et al. 2019

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Online monitoring of carbon fiber reinforced plastic (CFRP) ropes requires non-destructive testing (NDT) methods capable of detecting multiple damage types at high inspection speeds. Three NDT methods are evaluated on artificial and realistic imperfections in order to assess their suitability for online monitoring of CFRP ropes. To support testing, the microstructure and electrical conductivity of a carbon fiber rope is characterized. The compared methods are thermography via thermoelastic stress analysis, ultrasonic testing with commercial phased array transducers, and eddy current testing, supported by tailormade probes. While thermoelastic stress analysis and ultrasonics proved to be accurate methods for detecting damage size and the shape of defects, they were found to be unsuitable for high-speed inspection of a CFRP rope. Instead, contactless inspection using eddy currents is a promising solution for real-time online monitoring of CFRP ropes at high inspection speeds.

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Application of low frequency ECT method in noncontact detection and visualization of CFRP material

Cited by 77 publications

References 25 publications

Characterisation of carbon fibre-reinforced polymer composites through radon-transform analysis of complex eddy-current data

Characterisation of carbon fibre-reinforced polymer composites through radon-transform analysis of complex eddy-current data

A Novel Dual Modality Sensor With Sensitivities to Permittivity, Conductivity, and Permeability

Evaluation of Different Non-destructive Testing Methods to Detect Imperfections in Unidirectional Carbon Fiber Composite Ropes

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