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...
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10 citations
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
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
01 Jan 2022
2 citations
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.
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TL;DR: In this article, a numerical model is proposed to describe in-plane heat generation spatial response during induction processing of carbon fiber-reinforced thermoplastics, based on a unified approach that considers three possible heating mechanisms: fiber heating (Joule losses in fiber), noncontact junction heating (dielectric hysteresis), and contact junction heating at junctions).
Abstract: A numerical model is proposed to describe in-plane heat generation spatial response during induction processing of carbon fiber-reinforced thermoplastics. The model is based on a unified approach that considers three possible heating mechanisms: fiber heating (Joule losses in fiber), noncontact junction heating (dielectric hysteresis), and contact junction heating (Joule losses at junctions). A lumped meshing scheme is used to construct a numerical representation for cross-ply and angle-ply orientations of 2-ply prepreg stacks. Heat generation patterns are calculated based on voltage and current conservation laws and verified with induction heating of AS4 carbon fiber-reinforced polyetherimide (AS4/PEI) prepreg stacks. Excellent agreement is found except at very low angle-ply orientations where the predicted heating patterns show significant deviations from the experiment results. A sensitivity analysis is also performed to assess the relationship between heating patterns and material and process paramete...
18 citations
TL;DR: In this paper, a model was developed and verified to predict the strength and distribution of heat generation and distribution in carbon-fiber-based composites subjected to an alternating magnetic field.
18 citations
10 Mar 2008
TL;DR: In this paper, a Tone Burst Eddycurrent Thermography (TBET) technique was used to generate local heating inside the material, induced by pulsed/short-time induction heating.
Abstract: This paper reports on a Tone Burst Eddycurrent Thermography (TBET) technique that uses short‐time bursts of eddy‐currents induced in conducting media to generate local heating inside the material. The transient diffusion of the heat inside the material, induced by pulsed/short‐time induction heating, is imaged by measuring the transient temperature profiles on the surface of the material. The presence and characteristics of the defects inside the materials changes the surface temperature transients and thus can be used for the nondestructive evaluation (NDE) of conducting materials. Axisymmetric numerical models of the conventional transient thermography technique are used to benchmark the TBET technique. From the temperature profile data, temperature contrast information is obtained for the different defect depths. Temperature contrast data obtained for TBET, in this process, was compared with that obtained from conventional transient thermography data. It was found that the frequency of the eddy‐current...
15 citations
"Detection of dis-bond between honey..." refers background in this paper
...Induction thermography [11] relies on heat generated within the material due to eddy currents....
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TL;DR: In this article, a die-less forming process is described which is intended to be an eco-nomical method for manufacturing large, complex-shaped components from thermoplastic matrix, continuous-fiber composite materials.
Abstract: A die-less forming process is described which is intended to be an eco nomical method for manufacturing large, complex-shaped components from thermoplastic matrix, continuous-fiber composite materials. The concept is specialized to tapered shapes which are singly curved, long in their straight direction, and of arbitrary variable cross section along their length. An array of universal, computer-controlled rollers generates such shapes from initially flat laminates or stacks of prepreg sheet. Heating and bending of the material are strictly local operations occurring only within a small active zone at any one instant, thereby eliminating the need for fixed tooling and for large autoclaves or presses. The rollers are controlled using a "kinematically admissible bending" algorithm which requires interply sliding only in the local hot zone. Despite the fact that all of the regions not being formed are cold and rigid, the fibers of the composite are not forced to change length.Experimental verification to date...
14 citations
01 Jan 1992
13 citations