Evaluation of Defects in FRP Composites by NDT Techniques

Abstract

The very fast developments in the technology of composite materials have led to newer and wider applications of such promising materials. Composite materials offer a number of potential advantages in the aerospace field, particularly in safety-critical structures such as primary and secondary aircraft components. The presence of several types of defects such as voids, inclusions, debonds, improper cure, and delamination are almost common during the manufacture and use of composite materials. The proper assessment of such defects is necessary to utilize the full potential of these materials. This present study has been taken up to detect and characterize such defects using a thermal imaging technique. The technique is found to be deterministic in the acceptable level for the assessment of defects in polymer composites. The thermography, ultrasonics (A-scan and C-scan), and also microscopy (photo-microscope and scanning electron microscope) methods were used here to assess the defects. The detection and characterization of the wide range of defects requires a number of specialized non-destructive methods. The proper assessment of defects is essential, particularly in safety-critical structures such as primary and secondary aircraft components, to avoid catastrophic failure.

NDT evaluation of long-term bond durability of CFRP-structural systems applied to RC highway bridges

“…Impact-echo tests on concrete structures, such as CFRP plates applied to bridge structural members, produce distinctive waveforms and frequencies, in which dominant patterns in the number and distribution of peaks in the spectra are easily identified. Voids and de-laminations (flaws) in the CFRP-concrete structure change impact waveform patterns (frequency spectra) and provide qualitative and quantitative information about the existence and location of the structural deficiencies (Ray et al 2007). …”

Inspeção termográfica de danos por impacto em laminados de matriz polimérica reforçados por fibras de carbono

“…manufatura e de manutenção periódica de componentes estruturais. Além disso, a TIV favorece a obtenção de resultados confiáveis, quanto ao tamanho e à localização de defeitos e danos em laminados compósitos, de uma maneira rápida e eficiente [1][2][3][4][5] .…”

Effect of the Position of Defined Local Defect on the Mechanical Performance of Carbon-Fiber-Reinforced Plastics

“…In the recent years, the fabrication of defined local defects inserted FRPs has received considerable attention from the composite community [12][13][14][15][16][17][18][19][20][21][22]. In [12][13][14], defined local defect inserted FRPs were fabricated by blind holes of varying diameters in different layers of FRPs and defined local defects of polytetrafluorethylene (PTFE).…”

“…Also, carbon-fiber-reinforced plastics (CFRPs) with defined local defects containing aluminum oxide hollow balls and polystyrol balls were generated. Ray [15] used different types of materials, such as copper, zinc, gold, and aluminum foil, with different thicknesses to introduce artificial defects into the laminated composites during fabrication. The manufactured defined local defect incorporated FRPs are used for NDT, such as the quantitative evaluation of optical lock-in thermography or ultrasonic measurements of CFRPs, for the comparison of different NDTs, or for ultrasonic and thermographic NDT.…”