scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Detection of dis-bond between honeycomb and composite facesheet of an Inner Fixed Structure bond panel of a jet engine nacelle using infrared thermographic techniques

TL;DR: The Inner Fixed Structure (IFS) bond panel is a honeycomb sandwich panel with CFRP facesheet and a heat shield on one side, and a perforated CFRP faceheet on the other side, of a jet engine nacell as mentioned in this paper.
Abstract: The Inner Fixed Structure (IFS) bond panel is a honeycomb sandwich panel with CFRP facesheet and a heat shield on one side, and a perforated CFRP facesheet on the other side, of a jet engine nacell...
Citations
More filters
Journal ArticleDOI
TL;DR: In this article, a new scheme deploying induction thermography to detect fiber breakage and identify its orientation is proposed, which is experimentally demonstrated on samples with realistic fiber breakages produced in a controlled manner.
Abstract: Carbon fiber reinforced polymer (CFRP) composites are preferred for their specific strength and toughness. As fibers are the main load-bearing constituent of composites, fiber breakage has a significant effect on their strength and stiffness. The complex nature of damage involving oriented fiber breakages across multiple layers has posed a challenge to manufacturers and end-users alike. While detailed investigations of the damage have been carried out using micro-CT scans, assessment of oriented fiber breakages with field-deployable non-destructive techniques would facilitate our understanding significantly. A new scheme deploying induction thermography to detect fiber breakage and identify its orientation is proposed. It is experimentally demonstrated on samples with realistic fiber breakage produced in a controlled manner. Further, a numerical model capturing the proposed inspection mechanism is described.

6 citations

Journal ArticleDOI
TL;DR: In this article , an ultrasonic guided wave propagation in an elastic-viscoelastic (steel-rubber) bilayer structure was investigated and several wave features, such as amplitude, phase velocity and phase delay, were measured and compared to determine the characteristic changes of the A0 wave mode in the steel layer alone as well as in the bilayer structures.
Abstract: This study investigates the ultrasonic guided wave propagation in an elastic–viscoelastic (steel–rubber) bilayer structure. 2D finite element models are developed in the frequency domain to simulate the wave propagation in the steel–rubber bilayer structure. The guided wave A0 mode is generated in the bilayer with a contact L-wave probe and detected with an out-of-plane laser vibrometer. Several wave features, such as amplitude, phase velocity and phase delay, are measured and compared to determine the characteristic changes of the A0 wave mode in the steel layer alone as well as in the bilayer structure. Studies are also performed for the bilayer structure when excited from the steel and rubber surfaces. The amplitude and phase velocity of the A0 mode are reduced in the bilayer compared to the steel layer alone. The phase velocity of the A0 wave mode in the bilayer does not depend on the viscoelastic properties of the rubber layer, rather depends only on the elastic properties of the rubber layer. The viscoelastic rubber layer in the bilayer structure does not sustain any independent wave mode; instead, it carries the A0 mode of the steel layer alone as a modified A0 wave mode in the bilayer structure. A parametric numerical study of the viscoelasticity of the rubber layer in the bilayer structure shows that the attenuation of the modified A0 mode in the bilayer is more affected by the bulk S-wave attenuation than the bulk L-wave attenuation. The rate of attenuation of the modified A0 mode in the bilayer is faster on the rubber surface than on the steel surface. A study on the A0 wave mode interaction with the interfacial disbond between steel and rubber layers is also carried out.

2 citations

Book ChapterDOI
01 Jan 2022

2 citations

Journal ArticleDOI
01 Aug 2022-Sensors
TL;DR: Wang et al. as mentioned in this paper proposed a threshold denoising model based on wavelet transformation with bilateral filtering (WTBF) and a salient components enhancement method based on a multi-scale retinex algorithm combined with frequency-tuned salient region extraction (MSRFT).
Abstract: Thermal imaging is an important technology in low-visibility environments, and due to the blurred edges and low contrast of infrared images, enhancement processing is of vital importance. However, to some extent, the existing enhancement algorithms based on pixel-level information ignore the salient feature of targets, the temperature which effectively separates the targets by their color. Therefore, based on the temperature and pixel features of infrared images, first, a threshold denoising model based on wavelet transformation with bilateral filtering (WTBF) was proposed. Second, our group proposed a salient components enhancement method based on a multi-scale retinex algorithm combined with frequency-tuned salient region extraction (MSRFT). Third, the image contrast and noise distribution were improved by using salient features of orientation, color, and illuminance of night or snow targets. Finally, the accuracy of the bounding box of enhanced images was tested by the pre-trained and improved object detector. The results show that the improved method can reach an accuracy of 90% of snow targets, and the average precision of car and people categories improved in four low-visibility scenes, which demonstrates the high accuracy and adaptability of the proposed methods of great significance for target detection, trajectory tracking, and danger warning of automobile driving.

1 citations

References
More filters
Journal ArticleDOI
TL;DR: In this article, the wave-drag characteristics of an over-the-wing nacelle cone guration were analyzed and theoretical analyses and experimental measurements demonstrate that a wave-rate reduction can be achieved by locating the nacels front face near the shock-wave position on the wing.
Abstract: This paper presents the wave-drag characteristics of an over-the-wing nacelle cone guration. The e ow over the wing is accelerated such that the aerodynamic interference between the nacelle and the wing is critical in the transonic e ight regime.In general, locating nacellesoverthewing causesanunfavorableaerodynamicinterference and inducesa strongshock wave,which resultsina lowerdrag-divergenceMach number. Ifthenacelleislocated at the optimum position relative to the wing, however, the shock wave can be minimized, and drag divergence occurs at a Mach number higher than that for the clean-wing cone guration. Theoretical analyses and experimental measurements demonstrate that a wave-drag reduction can be achieved by locating the nacelle front face near the shock-wave position on the wing.

35 citations


"Detection of dis-bond between honey..." refers background in this paper

  • ...It provides an aerodynamic shell for minimum drag [1], incorporates de-icing capability [2], noise attenuation [3], and mechanisms to reverse engine thrust for braking [4]....

    [...]

Journal ArticleDOI
TL;DR: In this article, a finite element heat transfer analysis is used to predict thermal generation in carbon fiber reinforced polymers (CFRP), and the validity of the global thermal generation model is established through an experimental test matrix in which various specimen configurations are evaluated.
Abstract: Heating of continuous-carbon-fiber-reinforced polymers (CFRPs) by the application of an alternating magnetic field has been shown to be due to dielectric losses in the polymer. Models that predict thermal generation in these composites are input to a finite element heat transfer analysis, providing the predicted transient thermal profile in the plane of the laminate. The validity of the global thermal generation model is established through an experimental test matrix in which various specimen configurations are evaluated and compared with theoretical predictions of transient surface temperatures.

30 citations

Journal ArticleDOI
TL;DR: In this paper, the authors describe some approaches to thermal detection and characterization of impact damage in carbon fiber reinforced plastic (CFRP) of whose inspection is an important issue in several industrial areas, first of all, in aero space where subsurface defects might lead to catastrophic consequences.
Abstract: Thermal/infrared non-destructive testing (T/I NDT) is a particular application of IR thermography. T/I NDT is typically classified for passive and active, as well as for steady-state (stationary) and transient (non-stationary, or dynamic). Active T/I NDT can be classified by: (1) the type of thermal stimulation, (2) the arrangement of a sample and a thermal stimulation source, and (3) the size and shape of stimu l ated area. T/I NDT has proven to be a convenient technique for the detection of impact damage in composite materials due to the following: (1) graphite-based composites are similar to a blackbody by absorption/radiation properties in the infrared (IR) wavelength band, (2) their thermal conductivity is lower than that of metals but higher than of many non-metals thus ensuring reasonable temperature signals at convenient observation times, (3) impact damage leads to thin but laterally-extended air-filled defects which produce considerable thermal resistance to the in-depth heat flux, and (4) T/I NDT is a fast, remote and illustrative technique which, unlike ultrasonic inspection, does not require immersing a sample into water. This paper describes some approaches to thermal detection and characterization of impact damage in carbon fiber reinforced plastic (CFRP) of whose inspection is an important issue in several industrial areas, first of all, in aero space where subsurface defects might lead to catastrophic consequences. Realistic solutions of T/I NDT theoretical problems can be obtained by using 3D numerical models of heat conduction. Direct solutions allow better understanding of heat propagation in defect areas while inverse solutions ensure the evaluation of defect parameters, such as defect depth, size and thickness. Several characterization algorithms are available, with a one-sided T/I NDT procedure being better suited for the characterization of defect depth, while defect thickness is best evaluated in a two-sided procedure. In the case of CFRP composites, the defect characterization approaches are well developed, including the technique of dynamic thermal tomography, which enables a considerable reduction of surface clutter and allows the imaging of separate layers of a composite test sample.

30 citations


"Detection of dis-bond between honey..." refers background in this paper

  • ...beneath aircraft skins [7], notches under multi-ply composite patching, porosities [8], delamination [9], impact damages on carbon fibre reinforced plastic panels [10] and...

    [...]

Journal ArticleDOI
TL;DR: In this paper, an inversion method is proposed to determine simultaneously the electrical and the thermal properties of a given isotropic material from the time-temperature data obtained from tone-burst eddy current thermography (TBET).
Abstract: In this paper, an inversion method is proposed to determine simultaneously the electrical and the thermal properties of a given isotropic material from the time-temperature data obtained from tone-burst eddy current thermography (TBET). A multiphysics forward model for computing the surface temperature data was used in a genetic algorithm (GA) based inversion technique to determine the material properties such as electrical conductivity (σ), thermal conductivity (k), density (ρ), and specific heat (Cp) simultaneously. Different trials were carried out initially with simulated temperature data (with and without noise) and then validated with experiments.

27 citations

Journal ArticleDOI
TL;DR: In this article, an experimental and computational hybrid system is developed for detecting defects in various composite structures, which consists of an infrared thermal video system which measures the surface temperature distribution of the structure, a computer with a PIP-1024B image board which performs image processing of thermograms, and a HP ink jet XL printer.

21 citations


"Detection of dis-bond between honey..." refers background in this paper

  • ...beneath aircraft skins [7], notches under multi-ply composite patching, porosities [8], delamination [9], impact damages on carbon fibre reinforced plastic panels [10] and...

    [...]