THz QCL-based active imaging dedicated to non-destructive testing of composite materials used in aeronautics

Destic, Fabien; Petitjean, Yoann; Massenot, Sébastien; Mollier, Jean-Claude; Barbieri, Stefano

doi:10.1117/12.859247

Cited by 6 publications

(3 citation statements)

References 9 publications

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“…The non-destructive evaluation of composite materials [1][2][3][14][15][16] was mostly carried out by the use of THz time-domain spectroscopy (TDS). Nevertheless, there are many other techniques based, for example, on FMCW radar [17], CW imaging using quantum cascade lasers [18], a gas laser [9], or a Gunn diode [19]. In this work, our THz TDS system is used in reflection configuration in order to obtain information about the structure of the multilayer sample including the distribution and thicknesses of particular internal layers.…”

Section: Introductionmentioning

confidence: 99%

Precise Determination of Thicknesses of Multilayer Polyethylene Composite Materials by Terahertz Time-Domain Spectroscopy

Pałka

Krimi

Ospald

et al. 2015

J Infrared Milli Terahz Waves

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The multilayer structure of an ultra-high molecular weight polyethylene (UHMWPE) composite material was investigated in the terahertz (THz) spectral range by means of time-domain spectroscopy (TDS) technique. Such structures consist of many alternating layers of fibers, each being perpendicular to the other and each having a thickness of about 50 μm. Refractive indices of two composite samples and of a sample composed of four single layers (plies) having the same fiber orientation were determined for two orthogonal orientations of the electric field in a transmission TDS system. The birefringence of a single layer was measured, and the origin of this phenomenon is discussed. Using the TDS system in reflection, the formation of many pulses shifted in time was observed originating from reflections from interfaces of successive layers caused by the periodic modulation of the refractive index along the propagation of the THz radiation. This phenomenon is theoretically described and simulated by means of a transfer matrix method (TMM). A time-domain fitting procedure was used to determine thicknesses of all layers of the composite material. The reconstructed waveform based on the optimized thicknesses shows very good agreement with the measured waveform, with typical differences between measurements and simulations J Infrared Milli Terahz Waves (2015) between 3 and 7 μm (depending on the sample). As a result, we were able to determine the thicknesses of all layers of two multilayer (~200 plies) structures by means of the reflection TDS technology with high accuracy.

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Section: Introductionmentioning

confidence: 99%

Precise Determination of Thicknesses of Multilayer Polyethylene Composite Materials by Terahertz Time-Domain Spectroscopy

Pałka

Krimi

Ospald

et al. 2015

J Infrared Milli Terahz Waves

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“…Although other techniques based on a FMCW radar (Quast et al 2010) as well as CW imaging by means of quantum cascade lasers (Destic et al 2010), a gas laser (Redo-Sanchez et al 2006) or with a Gunn diode (Karpowicz et al 2005) were also studied.…”

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confidence: 99%

Detailed non-destructive evaluation of UHMWPE composites in the terahertz range

Pałka

Miedzińska

2013

Opt Quant Electron

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We report on the terahertz analysis of an internal structure of an ultra-high molecular weight polyethylene (UHMWPE) composite material, which is based on the HB10-tape from Dyneema . This type of composite is very hard and resistant and therefore it is often used to manufacture personal armors such as bulletproof vests and helmets. The multilayer structure of the UHMWPE composite was investigated by means of a raster scanning time domain spectroscopy technique in a reflection configuration. The mechanism of the formation of many shifted in time THz pulses (reflected from the internal layers of the sample) originates from the periodic modulation of the refractive index along the propagation of the radiation. This modulation is connected with alternate layers of fibers, each having different direction (perpendicular to each other). As a result we obtained the detailed three dimensional profile of the 3.3-mm thick sample with all 74 layers clearly visible. Thicknesses of all layers, having around 45 µm each, were determined. Moreover, it is also possible to identify internal defects i.e. delaminations in the internal structure of this composite material.

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“…Reflectance and transmittance in carbon fiber sheets, however, depend on the orientation of the fibers with respect to the polarization of the THz radiation: Not unlike in a wire-grid polarizer, THz radiation which is polarized perpendicularly to the fibers experiences a higher transmittance than for parallel polarization. The anisotropic THz characteristics of carbon fibers have been utilized to examine heat damage 15 as well as delamination 16 at or close to the surface. There are numerous further examples of THz methodologies and applications in NDT of composites.…”

Section: Introductionmentioning

confidence: 99%

Aeronautics composite material inspection with a terahertz time-domain spectroscopy system

et al. 2013

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Abstract. The usability of pulsed broadband terahertz radiation for the inspection of composite materials from the aeronautics industry is investigated, with the goal of developing a mobile time-domain spectroscopy system that operates in reflection geometry. A wide range of samples based on glass and carbon fiber reinforced plastics with various types of defects is examined using an imaging system; the results are evaluated both in time and frequency domain. The conductivity of carbon fibers prevents penetration of the respective samples but also allows analysis of coatings from the reflected THz pulses. Glass fiber composites are, in principle, transparent for THz radiation, but commonly with significant absorption for wavelengths >1 THz. Depending on depth, matrix material, and size, defects like foreign material inserts, delaminations, or moisture contamination can be visualized. If a defect is not too deep in the sample, its location can be correctly identified from the delay between partial reflections at the surface and the defect itself.

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THz QCL-based active imaging dedicated to non-destructive testing of composite materials used in aeronautics

Cited by 6 publications

References 9 publications

Precise Determination of Thicknesses of Multilayer Polyethylene Composite Materials by Terahertz Time-Domain Spectroscopy

Precise Determination of Thicknesses of Multilayer Polyethylene Composite Materials by Terahertz Time-Domain Spectroscopy

Detailed non-destructive evaluation of UHMWPE composites in the terahertz range

Aeronautics composite material inspection with a terahertz time-domain spectroscopy system

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