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Iowa State University

Review of Progress in Quantitative Nondestructive Evaluation

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Novel Methods To Measure Surface Wave Velocity By Using Laser-Generated Tone-Burst Surface Wave, Ju-Ho Lee, Jongbeom Kim, Kyung-Young Jhang Jan 2016

Novel Methods To Measure Surface Wave Velocity By Using Laser-Generated Tone-Burst Surface Wave, Ju-Ho Lee, Jongbeom Kim, Kyung-Young Jhang

Review of Progress in Quantitative Nondestructive Evaluation

Ultrasonic wave velocity is a characteristic of material, which is considered as a significant factor of nondestructive testing (NDT) techniques. Generally, bulk wave velocity is measured by Time-of-Flight (TOF) of pulse echo from back wall reflection; however, pulse-echo method cannot be applied to surface acoustic wave in a case that an edge does not exist in a close range. Even when we use through-transmission method, it is quite cumbersome to measure the accurate distance between transmitter and receiver; this problem is more critical when using contact angle transducers.

This study proposes two new signal processing methods to measure laser-generated surface ...


A Novel Thermosonic Imaging System For Non-Destructive Testing, Dan Xiang, Micheal Long, Carson Willey Jan 2016

A Novel Thermosonic Imaging System For Non-Destructive Testing, Dan Xiang, Micheal Long, Carson Willey

Review of Progress in Quantitative Nondestructive Evaluation

Thermosonic (Sonic IR) Imaging is a new nondestructive testing (NDT) technique that uses high-frequency sonic excitation together with infrared (IR) detection to image surface and subsurface defects. This Sonic IR imaging technique uses a short (usually fraction of a second) pulse of high frequency (typically 20-40 kHz) sound which is applied at some convenient point on the surface of the object under inspection to produce localized frictional heating at the defect. An IR camera images the heating of the surface resulting from the effects of friction or other irreversible internal surface interactions in the vicinity of defects. These effects result ...


Non-Contact Evaluation Of Residual Stress In Metals With Laser-Generated Surface Acoustic Waves And A Point-Like Fiber-Optic Sagnac Detector, Łukasz Ambrozinski, Ivan Pelivanov, Michael B. Prime, Matthew O’Donnell Jan 2016

Non-Contact Evaluation Of Residual Stress In Metals With Laser-Generated Surface Acoustic Waves And A Point-Like Fiber-Optic Sagnac Detector, Łukasz Ambrozinski, Ivan Pelivanov, Michael B. Prime, Matthew O’Donnell

Review of Progress in Quantitative Nondestructive Evaluation

Stress can remain in a material after the original load is removed. It can be purposely introduced to improve the properties of structural components, but can also be undesired, shortening a component’s lifetime, changing its original geometry or even leading to failure.

There is a large spectrum of problems where residual stress must be evaluated. An acousto-elastic approach is non-destructive and uses stress-dependent alterations in ultrasound (US) speed of bulk or surface modes [1]. However, these alterations are incredibly small (10-3 ÷ 10-5) and, thus, accurate measurement of both the US wave speed and propagation distance is required. Thickness measurement ...


Assessment Of Reflective Tapes On The Accuracy Of Displacement Measurement In Laser Doppler-Vibrometry, Mostafa Hasanian, Cliff J. Lissenden Jan 2016

Assessment Of Reflective Tapes On The Accuracy Of Displacement Measurement In Laser Doppler-Vibrometry, Mostafa Hasanian, Cliff J. Lissenden

Review of Progress in Quantitative Nondestructive Evaluation

Laser Doppler Vibrometry, LDV, is known to be a useful tool for measuring vibration and wave propagation for Non-destructive testing (NDT). Although LDV systems have many advantages, most notably they provide non-contact measurements, they often require surface enhancement [1, 2]. In order to improve the signal-to-noise ratio, reflective tapes are commonly used as a surface enhancement method in LDV applications. While accurate for low frequencies, measured displacements are not reliable once the frequency exceeds a threshold value. In this study, different tapes are mounted on the surface of an aluminum block, and out-of-plane displacements are recorded for frequencies from 0 ...


Monitoring Creep Damage And Microstructure Evolution In Concrete Using Nonlinear Rayleigh Waves, Gun Kim, Giovanni Loreto, Jin-Yeon Kim, Kimberly E. Kurtis, James J. Wall, Laurence J. Jacobs Jan 2016

Monitoring Creep Damage And Microstructure Evolution In Concrete Using Nonlinear Rayleigh Waves, Gun Kim, Giovanni Loreto, Jin-Yeon Kim, Kimberly E. Kurtis, James J. Wall, Laurence J. Jacobs

Review of Progress in Quantitative Nondestructive Evaluation

This paper uses nonlinear ultrasonic measurements to monitor creep-induced microstructural changes in concrete. A new NDE approach that enables the in-situ monitoring of the damage state in concrete is developed in which the second harmonic generation (SHG) technique using nonlinear Rayleigh surface waves is adapted to a cylindrical specimen. This cylindrical specimen is under a uniaxial compressive load (70% of the ultimate strength). The acoustic nonlinearity parameter, β is measured as a function of creep time. The following conclusions are drawn from the experiments: (1) the results suggest that the proposed NLU technique based on the SHG theory (β) is ...


Excitation Duration And Onset Time Effects In Active Thermography, Steven M. Shepard, James R. Lhota Jan 2016

Excitation Duration And Onset Time Effects In Active Thermography, Steven M. Shepard, James R. Lhota

Review of Progress in Quantitative Nondestructive Evaluation

In flash thermography, the surface of a test piece is excited by a pulse of light from a xenon flash lamp that is powered by a capacitor discharge. Typically, the lamps and power supplies are commercial units designed for photography applications. The equipment most often used for thermography has nominal energy output of 4-6 kJ and duration 3-5 msec. However, the actual optical output is more complex, since the energy rating pertains to the electrical discharge of the capacitors, and does not account for efficiency in converting electrical current to light, or resistive losses in the transfer of energy from ...


Study The Nonlinearity In Sonic Ir Imaging Nde, Xiaoyan Han, Qiuye Yu, Omar Obeidat Jan 2016

Study The Nonlinearity In Sonic Ir Imaging Nde, Xiaoyan Han, Qiuye Yu, Omar Obeidat

Review of Progress in Quantitative Nondestructive Evaluation

Sonic IR Imaging combines pulsed ultrasound excitation and infrared imaging to detect defects in materials. The sound pulse causes rubbing due to non-‐unison motion between faces of defects, and infrared sensors image the temperature map over the target to identify defects. It works in various materials, including metal/metal alloy, ceramics, and composite materials. Its biggest advantage is that it's a fast, wide area NDE technique. It takes only a fraction of a second or a few seconds, depending on the thermal properties of the target, for one test over a few square feet. However, due to the ...


Elastic Wave Fields Generated By Shear Horizontal Piezoelectric Fiber Patch (Sh-Pfp) Transducers: Parameter Study By Modelling And Laser Vibrometric Measurements, Bernd Köhler, Tobias Gaul, Frank Schubert, Uwe Lieske Jan 2016

Elastic Wave Fields Generated By Shear Horizontal Piezoelectric Fiber Patch (Sh-Pfp) Transducers: Parameter Study By Modelling And Laser Vibrometric Measurements, Bernd Köhler, Tobias Gaul, Frank Schubert, Uwe Lieske

Review of Progress in Quantitative Nondestructive Evaluation

Recently, a novel lightweight and thin piezoelectric transducer was proposed [1-3]. It generates in-plane surface tractions and thus shear horizontal elastic waves in both bulk materials and waveguides. The paper describes the principle of operation of this Shear Horizontal Piezoelectric Fiber Patch (SH-PFP). In continuation of the previous work, several variants of the SH-PFP are studied. The generated wavefield is characterized bywavefield snapshots and directivity functions. Both numerical simulation and measurements by 3D Laser Vibrometry are performed and the results are compared, showing a good agreement. We discuss possible further developments of the SH-PFP transducer to allow 1D directivity and ...


The Influence Of Pearlite Volume Fraction On Rayleigh Wave Propagation In A572 Grade 50 Steel, Zeynab Abbasi, Niloofar Nabili Tehrani, J. Ernesto Indacochea, Didem Ozevin Jan 2016

The Influence Of Pearlite Volume Fraction On Rayleigh Wave Propagation In A572 Grade 50 Steel, Zeynab Abbasi, Niloofar Nabili Tehrani, J. Ernesto Indacochea, Didem Ozevin

Review of Progress in Quantitative Nondestructive Evaluation

The acoustoelastic effect is the interaction between ultrasonic wave velocity and stress. To estimate the stress a perturbation signal is introduced and the shift in time of flight is measured at the receiving location. In addition to the stress, the wave velocity can be affected by the amount of phases in the material’s microstructure. This study investigates the changes in Rayleigh wave velocity for A572 grade 50 steel as a function of stress and pearlite phase volume fraction. In order to obtain different amounts of pearlite the samples are heat treated at 970 °C for time durations of 30 ...


Frequency Domain Reflectometry Nde For Aging Cables In Nuclear Power Plants, S. W. Glass, A. M. Jones, L. S. Fifield, T. S. Hartman Jan 2016

Frequency Domain Reflectometry Nde For Aging Cables In Nuclear Power Plants, S. W. Glass, A. M. Jones, L. S. Fifield, T. S. Hartman

Review of Progress in Quantitative Nondestructive Evaluation

Degradation of the cable jacket, electrical insulation, and other cable components of installed cables within nuclear power plants (NPPs) is known to occur as a function of age, temperature, radiation, and other environmental factors. System tests verify cable function under normal loads; however, demonstration of some cable’s ability to perform under exceptional loads associated with design-basis events is essential to assuring plant integrity. The cable’s ability to perform safely over the initial 40-year planned and licensed life has generally been demonstrated and there have been very few age-related cable failures.With greater than 1000 km of power, control ...


Evaluation Of Residual Stress In Ag/Glass Thin Films Using Dispersion Characteristic Of Rayleigh Wave, Taesung Park, Dongryul Kwak, Ikkeun Park Jan 2016

Evaluation Of Residual Stress In Ag/Glass Thin Films Using Dispersion Characteristic Of Rayleigh Wave, Taesung Park, Dongryul Kwak, Ikkeun Park

Review of Progress in Quantitative Nondestructive Evaluation

In this study, we suggest a method to measure residual stress of thin films nondestructively using dispersion characteristics of Rayleigh wave. Silver films were deposited on glass substrate by controlling the fabrication condition such as DC power and Ar pressure in order to verify a change of the surface acoustic wave velocity depending on the residual stress. The surface acoustic wave velocity of the thin films with different residual stress was measured using the V(z) curve method of scanning acoustic microscopy. To verify the actual residual stress in thin film, the X-ray diffraction method was applied. The change of ...


Application Of Diffracto Sight Ot The Nondestructive Inspection Of Aircraft Structures, Jerzy Komorowski, Ronald W. Gould, David L. Simpson, Omer Hageniers Jan 1993

Application Of Diffracto Sight Ot The Nondestructive Inspection Of Aircraft Structures, Jerzy Komorowski, Ronald W. Gould, David L. Simpson, Omer Hageniers

Review of Progress in Quantitative Nondestructive Evaluation

The D Sight optical set up was first assembled nearly ten years ago at Diffracto Ltd. It has received several patents, the first of which was in the United States [1]. Since the mid 1980’s, D Sight has been successfully applied to surface quality inspections, particularly in the automotive and plastics industries. Recently, Komorowski et al. [2–5] have shown several potential applications of D Sight in the field of nondestructive inspection of aircraft structures. The technique has been shown to be particularly effective in locating nonvisible impact damage on large surfaces of aircraft structures built from composite materials ...


High-Speed Time-Resolved Holography For Imaging Transient Events, Michael Ehrlich, James W. Wagner Jan 1993

High-Speed Time-Resolved Holography For Imaging Transient Events, Michael Ehrlich, James W. Wagner

Review of Progress in Quantitative Nondestructive Evaluation

A time-resolved holographic system was developed to study detonation dynamics in dispersed solid particulate explosives. This required a system capable of recording a rapid sequence of exposures during the approximate 1/µs lifetime of the detonation event.


Electronic Holography And Shearography Nde For Inspection Of Modern Materials And Structures, J. Clarady, M. Summers Jan 1993

Electronic Holography And Shearography Nde For Inspection Of Modern Materials And Structures, J. Clarady, M. Summers

Review of Progress in Quantitative Nondestructive Evaluation

Coherent optical techniques such as holography, shearography, and ESPI have been available for inspection applications for years. However, they are still not well known or widely used. In fact, they have sometimes been described as “a solution looking for a problem” and like so many new technologies, they may have been somewhat oversold. These optical NDE methods do, however, offer some impressive advantages over more conventional inspection techniques for the right applications. It is the intent of this paper to provide some basic information on how two of these optical methods, holography and shearography, work discuss capabilities and limitations of ...


Beam Profile Reflectometry: A New Technique For Thin Film Measurements, J. Fanton, J. Opsal, D. L. Willenborg, S. M. Kelso, Allan Rosencwaig Jan 1993

Beam Profile Reflectometry: A New Technique For Thin Film Measurements, J. Fanton, J. Opsal, D. L. Willenborg, S. M. Kelso, Allan Rosencwaig

Review of Progress in Quantitative Nondestructive Evaluation

In the manufacture of semiconductor devices, it is of critical importance to know the thickness and material properties of various dielectric and semiconducting thin films. Although there are many techniques for measuring these films, the most commonly used are reflection spectrophotometry [1,2] and ellipsometry [3]. In the former method, the normal- incidence reflectivity is measured as a function of wavelength. The shape of the reflectivity spectrum is then analyzed using the Fresnel equations to determine the thickness of the film. In some cases, the refractive index can also be determined provided that the dispersion of the optical constants are ...


Electronic Shearography: Current Capabilities, Potential Limitations, And Future Possibilities For Industrial Nondestructive Inspection, John Deaton Jr., Robert S. Rogowski Jan 1993

Electronic Shearography: Current Capabilities, Potential Limitations, And Future Possibilities For Industrial Nondestructive Inspection, John Deaton Jr., Robert S. Rogowski

Review of Progress in Quantitative Nondestructive Evaluation

Image-shearing speckle pattern interferometry, more commonly referred to as ‘shearography’, is a full-field, laser-based interferometric technique first developed for applications in experimental mechanics [1,2]. Shearography is sensitive to derivatives of the out-of-plane surface displacement of a body under load, as opposed to other full-field methods such as holographic interferometry and conventional speckle pattern interferometry, which typically contour the surface displacement directly [3]. The early shearography experiments used high-resolution photographic film to record images of the laser speckle patterns. In contrast to traditional film-based techniques, electronic shearography uses an electronic camera for image recording [4]. This technology, commercially available for ...


Quantitative Analysis Of A Class Of Subsurface Cracks Using Shearography And Finite Element Modeling, Leland Melvin, Brooks A. Childers, James P. Fulton Jan 1993

Quantitative Analysis Of A Class Of Subsurface Cracks Using Shearography And Finite Element Modeling, Leland Melvin, Brooks A. Childers, James P. Fulton

Review of Progress in Quantitative Nondestructive Evaluation

The application of a full field non-contacting measurement system for nondestructively evaluating (NDE) subsurface flaws in structures has been conducted using Electronic Shearography. Shearography has primarily been used as a qualitative tool for locating areas of stress concentration caused by anomalies in materials[1–4]. NASA has been applying optical techniques such as these to NDE inspection of aircraft lap joint integrity, composite material defects, and pressure vessel quality assurance. This paper examines a special class of defects manufactured in thin metal panels and serves as a testbed for interpreting the displacement gradients produced on a simple well-characterized sample with ...


Laser Shearographic Testing Of Foam Insulation On Cryogenic Fuel Tanks, Douglas Burleigh, James E. Engel, David R. Kuhns Jan 1993

Laser Shearographic Testing Of Foam Insulation On Cryogenic Fuel Tanks, Douglas Burleigh, James E. Engel, David R. Kuhns

Review of Progress in Quantitative Nondestructive Evaluation

The Centaur is a high-energy rocket used as a second stage to the Atlas launch vehicle. The Centaur is cryogenically fueled, using liquid hydrogen and liquid oxygen, and requires insulation to prevent fuel boiloff prior to launch. The original insulation system used on Centaur is a set of fiberglass honeycomb panels, which are jettisoned after launch. These panels are still used on the Atlas I version of Atlas/Centaur.


Shearography With Syncrhonized Pressure Stressing, Tom Chatters, Bruno Pouet, Sridhar Krishnaswamy Jan 1993

Shearography With Syncrhonized Pressure Stressing, Tom Chatters, Bruno Pouet, Sridhar Krishnaswamy

Review of Progress in Quantitative Nondestructive Evaluation

Non-destructive evaluation (NDE) techniques of optical video-based speckle interferometry are gaining importance as inspection tools, particularly by the aerospace industry [1,2]. An optical technique such as shearography is attractive to the NDE community largely because of its non-contacting nature, full-field measurement and fast inspection results. However, in order for this optical interferometric method to become widely used as an NDE tool, this technique must be made to be robust enough to operate in noisy environments typically found in industry settings. In this paper, we address these issues for the case of detection of disbonds using shearography in conjunction with ...


Practical Estimates Of The Errors Associated With The Governing Shearography Equation, John Fulton, M. Namkung, L. D. Melvin Jan 1993

Practical Estimates Of The Errors Associated With The Governing Shearography Equation, John Fulton, M. Namkung, L. D. Melvin

Review of Progress in Quantitative Nondestructive Evaluation

In a series of papers Hung[1–3] pioneered the development of shearography, an optical NDE technique that detects gradients of surface displacements. Its utility for qualitative flaw characterization has been demonstrated, and while there is a need for using shearography in NDE for quantitative analysis, a large amount of the research[2–7] has concentrated on the qualitative evaluation of structures and materials. The purpose of this paper is to begin building upon a foundation for the newly emerging quantitative shearography[8].


Noise Reduction Techniques For Electronic Speckle Interferometry, Bruno Pouet, Sridhar Krishnaswamy Jan 1993

Noise Reduction Techniques For Electronic Speckle Interferometry, Bruno Pouet, Sridhar Krishnaswamy

Review of Progress in Quantitative Nondestructive Evaluation

Video-based speckle interferometric methods such as electronic speckle pattern interferometry (ESPI) allow us to measure full-field surface deformation of a diffuse object. In this paper we show, in a first step, that the susceptibility of ESPI to noise can be substantially reduced [1] by synchronizing the optical interferometer and the object stressing system with the CCD image acquisition and processing system, and by performing what amounts to a repetitive sequence of rapid ESPI tests. In this manner, a stable fringe pattern can be obtained as long as the ambient noise is of sufficiently lower frequency than the video acquisition rate ...


Optical Probing Of Spherical Resonance Applied To Surface Defect Inspection, Chung-Kao Hsieh, B. T. Khuri-Yakub Jan 1993

Optical Probing Of Spherical Resonance Applied To Surface Defect Inspection, Chung-Kao Hsieh, B. T. Khuri-Yakub

Review of Progress in Quantitative Nondestructive Evaluation

Ceramic materials keep high strength under high temperature and nonlubricative environments. Ceramic bearing balls are more commonly used now to replace steel bearing balls to sustain high loads under such hostile environments. However, because ceramics are brittle, surface defects of ceramic bearing balls can cause total mechanical failure of the whole mechanism. In this paper, we shall discuss a quick, efficient, and accurate method for performing nondestructive testing of spherical objects. Currently, there are several techniques being used to inspect spherical objects. Here, we introduce a new noncontacting technique, the optical probing technique of spherical resonance. This technique has great ...


Seeing With Light, Sound, Microwaves, X-Rays, Gamma Rays, Etc., Glen Wade Jan 1990

Seeing With Light, Sound, Microwaves, X-Rays, Gamma Rays, Etc., Glen Wade

Review of Progress in Quantitative Nondestructive Evaluation

It is common to regard humans as being able to see only with light, but about a hundred years ago at the beginning of the modern era, along came x-rays and sonograms. By now technology has made it possible for us to see in a great many different ways. Important views such as underground pools of oil, tumors in the brain, fine structure in the rings of Saturn, ship wreckage on the bottom of the ocean, cracks in the ice packs of the Arctic, all these views and many more, completely unperceivable one hundred years ago, are available to us ...


Process Monitoring Of Polymer Matrix Composites Using Fluorescence Probes, Bruno Fanconi, Francis Wang, Robert Lowry Jan 1987

Process Monitoring Of Polymer Matrix Composites Using Fluorescence Probes, Bruno Fanconi, Francis Wang, Robert Lowry

Review of Progress in Quantitative Nondestructive Evaluation

On-line process monitoring and control are prerequisites for more efficient and reliable manufacture of polymer matrix composites. The cure process involves complex chemical and physical changes that must be adequately controlled to consistently produce high quality products. Of various changes that occur, the viscosity is particularly important as it influences fiber wetting, uniformity of resin distribution and consolidation of the reinforcement plies. In the usual cure cycle, the viscosity of the resin initially decreases as the temperature of the resin rises owing to the higher temperature of the autoclave and heat released by the exothermic chemical reactions of the cross-linking ...


Optical Generation Of Coherent Ultrahigh Frequency Surface Waves, Sheryl M. Gracewski, R. J. Dwayne Miller Jan 1987

Optical Generation Of Coherent Ultrahigh Frequency Surface Waves, Sheryl M. Gracewski, R. J. Dwayne Miller

Review of Progress in Quantitative Nondestructive Evaluation

It has been demonstrated [1–4] that coherent bulk acoustic waves can be holographically induced by the interference pattern of two intersecting picosecond laser pulses. The coupling between the optical and elastic fields can either be due to electrostriction or optical absorption which produces thermal stresses. The resulting waveform can then be detected by a third time-delayed laser pulse which diffracts off the density grating of the wave field. The elastic response within the laser spot caused by either coupling mechanism has been shown to consist of 1-D counter-propagating pressure waves. From the frequency and attenuation of the diffracted signal ...


Probing Through The Gas-Solid Interface With Thermal Waves: A Study Of The Temperature Distribution In The Gas And In The Solid, L. J. Inglehart, J. Jaarinen, P. K. Kuo, E. H. Le Gal La Salle Jan 1987

Probing Through The Gas-Solid Interface With Thermal Waves: A Study Of The Temperature Distribution In The Gas And In The Solid, L. J. Inglehart, J. Jaarinen, P. K. Kuo, E. H. Le Gal La Salle

Review of Progress in Quantitative Nondestructive Evaluation

Thermal wave nondestructive evaluation is one of the few NDE methods applicable to the characterization of ceramic and composite materials. As a near surface characterization technique, it has been shown to be useful for metals and semiconductors and has been developed for use with those materials. Limited work has been done with the technique on ceramics, with little effort to investigate the resulting fundamental differences which can occur in the case of insulating materials.


Internal Monitoring Of Acoustic Emission In Graphite-Epoxy Composites Using Imbedded Optical Fiber Sensors, K. D. Bennett, R. O. Claus, M. J. Pindera Jan 1987

Internal Monitoring Of Acoustic Emission In Graphite-Epoxy Composites Using Imbedded Optical Fiber Sensors, K. D. Bennett, R. O. Claus, M. J. Pindera

Review of Progress in Quantitative Nondestructive Evaluation

The monitoring of acoustic emission (AE) is an important technique for the nondestructive characterization of strained materials because time and frequency domain analyses of AE events yield information about the type, geometry, and location of defects, as well as how material failure may occur. The quantitative interpretation of AE event signatures is critically dependent upon the faithfulness of the acoustic transduction and signal processing system in reproducing localized stress wave amplitude as a function of time. Although the usual sensor for acoustic emission is the piezoelectric transducer, several investigators have considered the application of interferometric optical sensing techniques which offer ...


Optical Range Finder, G. Q. Xiao, D. B. Patterson, G. S. Kino Jan 1987

Optical Range Finder, G. Q. Xiao, D. B. Patterson, G. S. Kino

Review of Progress in Quantitative Nondestructive Evaluation

Recently, a great deal of interest has been shown in making accurate range measurements with good transverse definition. This capability makes it possible, in machine vision systems, to extract geometrical shape information from the images. In robot position sensing, it is important to determine the absolute distance instead of distance change so that noncontinuous measurements can be made without the need for calibration at start-up. A third application of great importance is to measure the shape and size of machined parts with a noncontacting sensor.


Magnetic Resonance Imaging In Medicine: Quantitative Tissue Characterization, Gary H. Glover Jan 1985

Magnetic Resonance Imaging In Medicine: Quantitative Tissue Characterization, Gary H. Glover

Review of Progress in Quantitative Nondestructive Evaluation

The medical community has long practiced the art of nondestructive evaluation in its various diagnostic imaging branches. Only within about the last decade, however, has there been an attempt to provide quantitative information to the clinical radiologist. The most important example of a system providing such information is the computed x-ray tomography (CT) scanner. The resulting digitally created images portray maps of an approximation to the electron density at discrete sampling points within the subject. Density resolution of the order of 0.1% and spatial resolution reaching 0.5 mm have become readily available.


Fiber Optics For A Damage Assessment System For Fiber Reinforced Plastic Composite Structures, Roger M. Crane, Aleksander B. Macander, James Gagorik Jan 1983

Fiber Optics For A Damage Assessment System For Fiber Reinforced Plastic Composite Structures, Roger M. Crane, Aleksander B. Macander, James Gagorik

Review of Progress in Quantitative Nondestructive Evaluation

There are a limited number of nondestructive evaluation techniques available for field inspection of large composite structures and practically no viable techniques for in-service inspection. With this in mind, an innovative Damage Assessment System is proposed which is based on a concept of using an optical fiber mesh, implanted into the body of a fiber reinforced composite structure. Such a mesh would become an integral part of the structure during the course of its fabrication. The selection of the mesh fibers would be predicated on their strain to failure characteristics and strain compatibility with the base, composite reinforcing fibers. This ...