Quantitative Thermal Wave Imaging of Corrosion on Aircraft

Pulse-echo thermal wave imaging is accomplished using a pulsed heat source (usually high-power flash lamps), an infrared (IR) video camera, and image processing hardware and software, all of which is controlled by a personal computer. The system has been described in detail elsewhere. [1,2] Figure 1 shows the thermal wave imaging system in operation at the FAA’s Aging Aircraft NDI Validation Center (AANC). As can seen from Fig. 1, the imaging head is hand-held. The computer, power supplies, etc., are located some distance away at the end of a fifty-foot long cable, the other end of which can be seen attached to the imaging head in Fig. 1. This same cable also carries the power for the flashlamps and the control signals from the computer. To make an image, the imaging head is held in place for three seconds. During this time, the flashlamps are fired, and a sequence of images is acquired and transferred to the computer’s hard disk. The head can then be moved to the next area to be imaged. An area of approximately a square foot is imaged at each flash by the system, so that wide areas of the aircraft can be covered very rapidly

MISpheroID: a knowledgebase and transparency tool for minimum information in spheroid identity

Spheroids are three-dimensional cellular models with widespread basic and translational application across academia and industry. However, methodological transparency and guidelines for spheroid research have not yet been established. The MISpheroID Consortium developed a crowdsourcing knowledgebase that assembles the experimental parameters of 3,058 published spheroid-related experiments. Interrogation of this knowledgebase identified heterogeneity in the methodological setup of spheroids. Empirical evaluation and interlaboratory validation of selected variations in spheroid methodology revealed diverse impacts on spheroid metrics. To facilitate interpretation, stimulate transparency and increase awareness, the Consortium defines the MISpheroID string, a minimum set of experimental parameters required to report spheroid research. Thus, MISpheroID combines a valuable resource and a tool for three-dimensional cellular models to mine experimental parameters and to improve reproducibility

Thermal Wave Imaging of Disbonding and Corrosion on Aircraft

Thermal wave imaging is emerging as a strong competitor to conventional nondestructive aircraft inspection techniques. Its strengths are in its ability to do rapid, wide-area, contactless imaging to detect corrosion and disbonding. It readily lends itself to the inspection of both metallic and composite aircraft structures. Recently [1], we have described the evolution of thermal wave hardware, and the role of the FAA’s NDI Validation Center in that evolution. In this report, we provide illustrative thermal wave images which show corrosion and disbonding on the B737 testbed aircraft at the NDI Validation Center. By showing sequences of images at successive times after the pulse-heating of the aircraft surface, we show that the greatest detail of subsurface corrosion occurs at very early times, thus mandating the use of rapid imaging techniques. More detailed laboratory studies confirming this conclusion are provided in a separate study by some of the authors [2]

MISpheroID: a knowledgebase and transparency tool for minimum information in spheroid identity

Spheroids are three-dimensional cellular models with widespread basic and translational application across academia and industry. However, methodological transparency and guidelines for spheroid research have not yet been established. The MISpheroID Consortium developed a crowdsourcing knowledgebase that assembles the experimental parameters of 3,058 published spheroid-related experiments. Interrogation of this knowledgebase identified heterogeneity in the methodological setup of spheroids. Empirical evaluation and interlaboratory validation of selected variations in spheroid methodology revealed diverse impacts on spheroid metrics. To facilitate interpretation, stimulate transparency and increase awareness, the Consortium defines the MISpheroID string, a minimum set of experimental parameters required to report spheroid research. Thus, MISpheroID combines a valuable resource and a tool for three-dimensional cellular models to mine experimental parameters and to improve reproducibility. © 2021, The Author(s)

Thermal Wave Imaging of Disbonding and Corrosion on Aircraft

Thermal wave imaging is emerging as a strong competitor to conventional nondestructive aircraft inspection techniques. Its strengths are in its ability to do rapid, wide-area, contactless imaging to detect corrosion and disbonding. It readily lends itself to the inspection of both metallic and composite aircraft structures. Recently [1], we have described the evolution of thermal wave hardware, and the role of the FAA’s NDI Validation Center in that evolution. In this report, we provide illustrative thermal wave images which show corrosion and disbonding on the B737 testbed aircraft at the NDI Validation Center. By showing sequences of images at successive times after the pulse-heating of the aircraft surface, we show that the greatest detail of subsurface corrosion occurs at very early times, thus mandating the use of rapid imaging techniques. More detailed laboratory studies confirming this conclusion are provided in a separate study by some of the authors [2].</p

NDE of Corrosion and Disbonding on Aircraft Using Thermal Wave Imaging

Thermal wave imaging has been shown to have the quantitative capability for measuring aircraft skin corrosion thinning. [1] For single fuselage skin, the technique is sensitive to less than 1% material loss, and can make rapid (a few seconds) measurements which compare well with direct micrometer readings. The method uses pulse heating of the aircraft by means of photographic flashlamps which are enclosed in a metal shroud to trap and funnel the light uniformly onto the surface during the 5msec duration of the pulse. An infrared (IR) focal plane array camera, aimed and focused at the surface through an opening in the rear of the hand-held shroud, monitors the rapid cooling of that surface following the pulse. Metal doublers, bonded to the inside surface of the fuselage, cause the outside surface just above them to cool more rapidly, whereas regions which are thinned because of internal surface corrosion cool less rapidly. By appropriate selection of the gate time(s) for monitoring the cooling, these features show up as distinct dark (light) features in the resulting thermal wave images. The system we have developed at Wayne State University has the electronics and computer mounted on a two-wheeled cart, and the imaging head (shroud/lamps/camera) remotely located and connected to the cart by a long (50-ft) umbilical cable (shown in the photo from the FAA’s Airworthiness Assurance Validation Center (AANC) hangar in Albuquerque, NM).</p

QNDE of a 3-D Carbon-Carbon Composite Using Photoacoustic Microscopy

A composite is composed of several distinct material components, one of which is contiguous and forms a matrix. The overall properties of the composite material are some average of the properties of its components. The fiber reinforced composites, like the carbon-carbon composites, are heterogenous materials consisting of reinforcement fibers embedded in a matrix. In most cases, the matrix may be considered homogenous and isotropic, but not the fiber reinforcement, which are highly anisotropic fibers. These fibers are grouped into yarns and woven in specific directions. The thermal properties of the matrix and the fibers are usually different. Thermally, the fibers are more conductive than the matrix and play a dominant role in the heat transfer through the composite, especially when the heat flux is parallel to one of the fiber reinforcement directions. The complex nature and strong thermal anisotropy of the fiber reinforcement makes characterization and modeling of 3-D carbon-carbon composites very difficult. Recently, [1,2,3,4,5] using the flash method for measuring thermal diffusivity, the in-situ thermal properties of the constituents of composite materials were determined.</p

Quantitative Thermal Wave Imaging of Corrosion on Aircraft

Pulse-echo thermal wave imaging is accomplished using a pulsed heat source (usually high-power flash lamps), an infrared (IR) video camera, and image processing hardware and software, all of which is controlled by a personal computer. The system has been described in detail elsewhere. [1,2] Figure 1 shows the thermal wave imaging system in operation at the FAA’s Aging Aircraft NDI Validation Center (AANC). As can seen from Fig. 1, the imaging head is hand-held. The computer, power supplies, etc., are located some distance away at the end of a fifty-foot long cable, the other end of which can be seen attached to the imaging head in Fig. 1. This same cable also carries the power for the flashlamps and the control signals from the computer. To make an image, the imaging head is held in place for three seconds. During this time, the flashlamps are fired, and a sequence of images is acquired and transferred to the computer’s hard disk. The head can then be moved to the next area to be imaged. An area of approximately a square foot is imaged at each flash by the system, so that wide areas of the aircraft can be covered very rapidly.</p

Studying Candidal adhesin and biofilm formation using atomic force microscopy (AFM)

Thermal wave imaging has been shown to have the quantitative capability for measuring aircraft skin corrosion thinning. [1] For single fuselage skin, the technique is sensitive to less than 1% material loss, and can make rapid (a few seconds) measurements which compare well with direct micrometer readings. The method uses pulse heating of the aircraft by means of photographic flashlamps which are enclosed in a metal shroud to trap and funnel the light uniformly onto the surface during the 5msec duration of the pulse. An infrared (IR) focal plane array camera, aimed and focused at the surface through an opening in the rear of the hand-held shroud, monitors the rapid cooling of that surface following the pulse. Metal doublers, bonded to the inside surface of the fuselage, cause the outside surface just above them to cool more rapidly, whereas regions which are thinned because of internal surface corrosion cool less rapidly. By appropriate selection of the gate time(s) for monitoring the cooling, these features show up as distinct dark (light) features in the resulting thermal wave images. The system we have developed at Wayne State University has the electronics and computer mounted on a two-wheeled cart, and the imaging head (shroud/lamps/camera) remotely located and connected to the cart by a long (50-ft) umbilical cable (shown in the photo from the FAA’s Airworthiness Assurance Validation Center (AANC) hangar in Albuquerque, NM)

Dosage‐Dependent Antimicrobial Activity of DNA‐Histone Microwebs Against Staphylococcus Aureus

Neutrophil extracellular traps (NETs) are antimicrobial cobweb‐structured materials produced by immune cells for clearance of pathogens in the body, but are paradoxically associated with biofilm formation and exacerbated lung infections. To provide a better materials perspective on the pleiotropic roles played by NETs at diverse compositions/concentrations, a NETs‐like material (called “microwebs”, abbreviated as μwebs) is synthesized for decoding the antimicrobial activity of NETs against Staphylococcus aureus in infection‐relevant conditions. It is shown that μwebs composed of low‐to‐intermediate concentrations of DNA‐histone complexes successfully trap and inhibit S. aureus growth and biofilm formation. However, with growing concentrations and histone proportions, the resulting microwebs appear gel‐like structures accompanied by reduced antimicrobial activity that can even promote the formation of S. aureus biofilms. The simplified model of NETs provides materials‐based evidence on NETs‐relevant pathology in the development of biofilms.“Microwebs”, a web‐like DNA structure mimicking the neutrophil extracellular traps (NETs) shows antimicrobial activity against Staphylococcus aureus at physiological conditions, but it paradoxically induces biofilm formation at higher concentrations. This paradigm can be explained under the framework of electrostatic interactions between DNA, histone, and bacterial cell walls, which provides a materials‐based insight for understanding the NETs‐relevant pathology in the biofilm disease.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/170195/1/admi202100717_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/170195/2/admi202100717.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/170195/3/admi202100717-sup-0001-SuppMat.pd