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In this Progress Report, we describe our continuing research activities concerning the development and implementation of advanced ultrasonic nondestructive evaluation methods applied to the inspection and characterization of complex composite structures. We explore the feasibility of implementing medical linear array imaging technology as a viable ultrasonic-based nondestructive evaluation method to inspect and characterize complex materials. As an initial step toward the application of linear array imaging technology to the interrogation of a wide range of complex composite structures, we present images obtained using an unmodified medical ultrasonic imaging system of two epoxy-bonded aluminum plate specimens, each with intentionally disbonded regions. These images are compared with corresponding conventional ultrasonic contact transducer measurements in order to assess whether these images can detect disbonded regions and provide information regarding the nature of the disbonded region. We present a description of a standoff/delay fixture which has been designed, constructed, and implemented on a Hewlett-Packard SONOS 1500 medical imaging system. This standoff/delay fixture, when attached to a 7.5 MHz linear array probe, greatly enhances our ability to interrogate flat plate specimens. The final section of this Progress Report describes a woven composite plate specimen that has been specially machined to include intentional flaws. This woven composite specimen will allow us to assess the feasibility of applying linear array imaging technology to the inspection and characterization of complex textile composite materials. We anticipate the results of this on-going investigation may provide a step toward the development of a rapid, real-time, and portable method of ultrasonic inspection and characterization based on linear array technology.

In this Progress Report, we describe our continuing research activities concerning the development and implementation of advanced ultrasonic nondestructive evaluation methods applied to the inspection and characterization of complex composite structures. We explore the feasibility of implementing medical linear array imaging technology as a viable ultrasonic-based nondestructive evaluation method to inspect and characterize complex materials. As an initial step toward the application of linear array imaging technology to the interrogation of a wide range of complex composite structures, we present images obtained using an unmodified medical ultrasonic imaging system of two epoxy-bonded aluminum plate specimens, each with intentionally disbonded regions. These images are compared with corresponding conventional ultrasonic contact transducer measurements in order to assess whether these images can detect disbonded regions and provide information regarding the nature of the disbonded region. We present a description of a standoff/delay fixture which has been designed, constructed, and implemented on a Hewlett-Packard SONOS 1500 medical imaging system. This standoff/delay fixture, when attached to a 7.5 MHz linear array probe, greatly enhances our ability to interrogate flat plate specimens. The final section of this Progress Report describes a woven composite plate specimen that has been specially machined to include intentional flaws. This woven composite specimen will allow us to assess the feasibility of applying linear array imaging technology to the inspection and characterization of complex textile composite materials. We anticipate the results of this on-going investigation may provide a step toward the development of a rapid, real-time, and portable method of ultrasonic inspection and characterization based on linear array technology.

A report of the activity related to the research on the role of defects and electronic structure on the sensitivity of energetic materials detonation.

Techniques have been developed for the quantitative characterization of particulate materials by computer evaluation of scanning electron microscope images (CESEMI). The full CESEMI analysis is particularily applicable to particles in the size range of 0.1 to 100 micrometers diameter. It measures, particle-by-particle, the following basic parameters: Project areas; Perimeter; Major axis of fitted ellipse; Minor axis of fitted ellipse; Orientation of major axis; and Particle type as deduced from characteristic x-ray signals for the elements. The technique is not described in detail here. On the other hand, the simple image analysis procedures have been only recently developed and are described in detail.

The objective of this Review was to evaluate the potential of new and/or improved techniques for predicting the performance of composite materials. A total of thirty-five technical papers were presented at the Review. The topics covered by session were: Cure Monitoring; Moisture; Predictive Composite Characterization; Advances of Significance to Composites; and Recapitulation.

The objective of this Review was to evaluate the potential of new and/or improved techniques for predicting the performance of composite materials. A total of thirty-five technical papers were presented at the Review. The topics covered by session were: Cure Monitoring; Moisture; Predictive Composite Characterization; Advances of Significance to Composites; and Recapitulation.

The development and implementation of advanced ultrasonic nondestructive evaluation methods applied to the characterization of composite materials requires a better understanding of the physics underlying the interaction of ultrasound with the material. The purpose of this investigation is to identify and characterize the features of complex, three dimensional materials that limit the ability of ultrasound to detect flaws in this broad class of emerging materials. In order to explore the interaction of ultrasound with such complex media, we investigate the characteristics of ultrasonic fields which have propagated through samples with complex geometries and/or internal architecture. We focus on the physics that underlies the detection of flaws in such materials.

In this Progress Report, the author describes the continuing research to explore the feasibility of implementing medical linear array imaging technology as a viable ultrasonic-based nondestructive evaluation method to inspect and characterize complex materials. Images obtained using an unmodified medical ultrasonic imaging system of a bonded aluminum plate sample with a simulated disbond region are presented. The disbond region was produced by adhering a piece of plain white paper to a piece of cellophane tape and applying the paper-tape combination to one of the aluminum plates. Because the area under the paper was not adhesively bonded to the aluminum plate, this arrangement more closely simulates a disbond. Images are also presented for an aluminum plate sample with an epoxy strip adhered to one side to help provide information for the interpretation of the images of the bonded aluminum plate sample containing the disbond region. These images are compared with corresponding conventional ultrasonic contact transducer measurements in order to provide information regarding the nature of the disbonded region. The results of this on-going investigation may provide a step toward the development of a rapid, real-time, and portable method of ultrasonic inspection and characterization based on linear array technology. In Section 2 of this Progress Report, the preparation of the aluminum plate specimens is described. Section 3 describes the method of linear array imaging. Sections 4 and 5 present the linear array images and results from contact transducer measurements, respectively. A discussion of the results are presented in Section 6.

An overall goal of this research has been to enhance our understanding of the scientific principles necessary to develop advanced ultrasonic nondestructive techniques for the quantitative characterization of advanced composite structures. To this end, we have investigated a thin woven composite (5-harness biaxial weave). We have studied the effects that variations of the physical parameters of the experimental setup can have on the ultrasonic determination of the material properties for this thin composite. In particular, we have considered the variation of the nominal center frequency and the f-number of the transmitting transducer which in turn address issues such as focusing and beam spread of ultrasonic fields. This study has employed a planar, two-dimensional, receiving pseudo-array that has permitted investigation of the diffraction patterns of ultrasonic fields. Distortion of the ultrasonic field due to the spatial anisotropy of the thin composite has prompted investigation of the phenomenon of phase cancellation at the face of a finite-aperture, piezoelectric receiver. We have performed phase-sensitive and phase-insensitive analyses to provide a measure of the amount of phase cancellation at the face of a finite-aperture, piezoelectric receiver. The pursuit of robust measurements of received energy (i.e., those not susceptible to phase cancellation at the face of a finite-aperture, piezoelectric receiver) supports the development of robust techniques to determine material properties from measure ultrasonic parameters.

Laser ablation provides a mechanism whereby non-volatile material can be ejected into the gas phase. As a novel way of making coatings and interesting thin films, PLD has been in use for a number of years and has found application in areas ranging from the growth of high temperature superconductors to diamond thin-film generation. PLD is initiated by laser ablation, which is essentially evaporation of a material by a high-powered laser. Subsequently, ejected material is deposited at a desired substrate. With regard to hard coatings such as SiC or TiC, PLD is being used to coat micro-electromechanical systems (MEMS) devices, which are becoming increasing important in Air Force related activities. Once put into space, it is clear that wear on components constitutes a serious maintenance issue, and minimizing wear is desirable. In terms of applying a hard coating, the advantages of PLD are numerous. The most important ones include ease of deposition, possibility of obtaining crystalline films with good adhesion and high optical response at low temperatures (even at room temperature), and the ability to reproduce the stoichiometry of the target in the film, including that of multi-component targets.

Journal of Research of the National Bureau of Standards

In this Progress Report, we describe our current research activities concerning the development and implementation of advanced ultrasonic nondestructive evaluation methods applied to the characterization of stitched composite materials and bonded aluminum plate specimens. One purpose of this investigation is to identify and characterize specific features of polar backscatter interrogation which enhance the ability of ultrasound to detect flaws in a stitched composite laminate. Another focus is to explore the feasibility of implementing medical linear array imaging technology as a viable ultrasonic-based nondestructive evaluation method to inspect and characterize bonded aluminum lap joints. As an approach to implementing quantitative ultrasonic inspection methods to both of these materials, we focus on the physics that underlies the detection of flaws in such materials.

A final report of the activity related to the research on the role of defects and electronic structure on the sensitivity of energetic materials to detonation.

This article is from BMC Proceedings , volume 5 . Abstract Raw materials are a critical part of any cell culture medium; therefore, it is of utmost importance to understand and characterize them for high-quality product. The raw material characterization (RMC) program at SAFC focuses on individual screening of raw materials both analytically and biologically. The goal of the program is to develop the best-in-class knowledge base of the raw materials used in SAFC’s media formulations and their impact on performance of products.

Millimeter-wave reflection and transmission measurements were performed on various composite materials in order to characterize the changes in the structural and optical properties after being subjected to thermal and mechanical degradation.

The properties of the buried Si-SiO2 interface, the concentration of structural defects, and the level of contamination have been monitored nondestructively via their effect on the surface and bulk components of recombination lifetime by a laser/microwave photoconductance technique. It has been found for single and multiple implant/anneal SIMOX material that the bulk recombination lifetime decreases if the annealing alone (no implantation), or both implantation and annealing processes are applied. However, a bulk lifetime recovery for multiple implant/anneal process is observed after the second and third processing steps. In addition, the superficial layer and Si-SiO2 interface still contain a very high density of electrical defects even after the structural damage removing/oxide forming high temperature treatment. This defect density results in a surface recombination velocity on the order of 1000 cm/s, two or three orders of magnitude more than a surface subjected to annealing alone (without implantation), and only one order less than non-annealed, implanted material. (MM)

In this Progress Report, we describe our further development of advanced ultrasonic nondestructive evaluation methods applied to the characterization of anisotropic materials. We present images obtained from experimental measurements of ultrasonic diffraction patterns transmitted through water only and transmitted through water and a thin woven composite. All images of diffraction patterns have been included on the accompanying CD-ROM in the JPEG format and Adobe TM Portable Document Format (PDF), in addition to the inclusion of hardcopies of the images contained in this report. In our previous semi-annual Progress Report (NAG 1-1848, December, 1996), we proposed a simple model to simulate the effect of a thin woven composite on an insonifying ultrasonic pressure field. This initial approach provided an avenue to begin development of a robust measurement method for nondestructive evaluation of anisotropic materials. In this Progress Report, we extend that work by performing experimental measurements on a single layer of a five-harness biaxial woven composite to investigate how a thin, yet architecturally complex, material interacts with the insonifying ultrasonic field. In Section 2 of this Progress Report we describe the experimental arrangement and methods for data acquisition of the ultrasonic diffraction patterns upon transmission through a thin woven composite. We also briefly describe the thin composite specimen investigated. Section 3 details the analysis of the experimental data followed by the experimental results in Section 4. Finally, a discussion of the observations and conclusions is found in Section 5.

Two new techniques have been developed to characterize Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) based ferroelectric single crystals: (i) electro-thermal imaging, and (ii) single crystal x-ray diffraction in the transmission mode. (i) Electro-thermal imaging is a remote sensing technique that can detect the polarization direction and poling state of a whole crystal slice. This imaging technique utilizes an IR camera to determine the field induced temperature change and does not require any special or destructive sample preparation. In the resulting images it is possible to distinguish regions of 180 deg domains. This powerful technique can be used remotely during poling to determine the poling state of the crystal to avoid over-poling that can result in inferior properties and/or cracking of the crystals. Electro-thermal imaging produced the first direct observations of polarization rotation. Under bipolar field, the domains near the corners were the first to switch direction. As the field increased above the coercive field, domains at the center part of the crystals switched direction. (ii) X-ray diffraction in the transmission mode has long been used in structure determination of organic crystals and proteins; however, it is not used much to characterize inorganic systems. 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystals were examined by this XRD technique for the first time, and a never-before-seen super-lattice was revealed with a doubling of the unit cell in all three directions, giving a cell volume eight times that of a traditional perovskite unit cell. The significance of the super-lattice peaks increased with poling, indicating a structural contribution to ordering. Lack of such observations by electron diffraction in the transmission electron microscope examinations suggests the presence of a bulk effect.

Two new techniques have been developed to characterize Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) based ferroelectric single crystals: (i) electro-thermal imaging, and (ii) single crystal x-ray diffraction in the transmission mode. (i) Electro-thermal imaging is a remote sensing technique that can detect the polarization direction and poling state of a whole crystal slice. This imaging technique utilizes an IR camera to determine the field induced temperature change and does not require any special or destructive sample preparation. In the resulting images it is possible to distinguish regions of 180 deg domains. This powerful technique can be used remotely during poling to determine the poling state of the crystal to avoid over-poling that can result in inferior properties and/or cracking of the crystals. Electro-thermal imaging produced the first direct observations of polarization rotation. Under bipolar field, the domains near the corners were the first to switch direction. As the field increased above the coercive field, domains at the center part of the crystals switched direction. (ii) X-ray diffraction in the transmission mode has long been used in structure determination of organic crystals and proteins; however, it is not used much to characterize inorganic systems. 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystals were examined by this XRD technique for the first time, and a never-before-seen super-lattice was revealed with a doubling of the unit cell in all three directions, giving a cell volume eight times that of a traditional perovskite unit cell. The significance of the super-lattice peaks increased with poling, indicating a structural contribution to ordering. Lack of such observations by electron diffraction in the transmission electron microscope examinations suggests the presence of a bulk effect.

Laser ablation provides a mechanism whereby non-volatile material can be ejected into the gas phase. As a novel way of making coatings and interesting thin films, PLD has been in use for a number of years and has found application in areas ranging from the growth of high temperature superconductors to diamond thin-film generation. PLD is initiated by laser ablation, which is essentially evaporation of a material by a high-powered laser. Subsequently, ejected material is deposited at a desired substrate. With regard to hard coatings such as SiC or TiC, PLD is being used to coat micro-electromechanical systems (MEMS) devices, which are becoming increasing important in Air Force related activities. Once put into space, it is clear that wear on components constitutes a serious maintenance issue, and minimizing wear is desirable. In terms of applying a hard coating, the advantages of PLD are numerous. The most important ones include ease of deposition, possibility of obtaining crystalline films with good adhesion and high optical response at low temperatures (even at room temperature), and the ability to reproduce the stoichiometry of the target in the film, including that of multi-component targets.

The objective of this review is to evaluate the potential of new and/or improved techniques and combinations thereof in the prediction of field life of polymeric and composite materials in military hardware. Various types of spectroscopic methods, chemical separation techniques, and dielectric and thermal methods of analysis were used to determine mechanisms and rates of deterioration on these materials after prolonged exposure to various weather conditions. (Author, modified-PL).

An overall goal of this research has been to enhance our understanding of the scientific principles necessary to develop advanced ultrasonic nondestructive techniques for the quantitative characterization of advanced composite structures. To this end, we have investigated a thin woven composite (5-harness biaxial weave). We have studied the effects that variations of the physical parameters of the experimental setup can have on the ultrasonic determination of the material properties for this thin composite. In particular, we have considered the variation of the nominal center frequency and the f-number of the transmitting transducer which in turn address issues such as focusing and beam spread of ultrasonic fields. This study has employed a planar, two-dimensional, receiving pseudo-array that has permitted investigation of the diffraction patterns of ultrasonic fields. Distortion of the ultrasonic field due to the spatial anisotropy of the thin composite has prompted investigation of the phenomenon of phase cancellation at the face of a finite-aperture, piezoelectric receiver. We have performed phase-sensitive and phase-insensitive analyses to provide a measure of the amount of phase cancellation at the face of a finite-aperture, piezoelectric receiver. The pursuit of robust measurements of received energy (i.e., those not susceptible to phase cancellation at the face of a finite-aperture, piezoelectric receiver) supports the development of robust techniques to determine material properties from measure ultrasonic parameters.

An overall goal of this research has been to enhance our understanding of the scientific principles necessary to develop advanced ultrasonic nondestructive techniques for the quantitative characterization of advanced composite structures. To this end, we have investigated a thin woven composite (5-harness biaxial weave). We have studied the effects that variations of the physical parameters of the experimental setup can have on the ultrasonic determination of the material properties for this thin composite. In particular, we have considered the variation of the nominal center frequency and the f-number of the transmitting transducer which in turn address issues such as focusing and beam spread of ultrasonic fields. This study has employed a planar, two-dimensional, receiving pseudo-array that has permitted investigation of the diffraction patterns of ultrasonic fields. Distortion of the ultrasonic field due to the spatial anisotropy of the thin composite has prompted investigation of the phenomenon of phase cancellation at the face of a finite-aperture, piezoelectric receiver. We have performed phase-sensitive and phase-insensitive analyses to provide a measure of the amount of phase cancellation at the face of a finite-aperture, piezoelectric receiver. The pursuit of robust measurements of received energy (i.e., those not susceptible to phase cancellation at the face of a finite-aperture, piezoelectric receiver) supports the development of robust techniques to determine material properties from measure ultrasonic parameters.

Reactive materials show a promising future in an assortment of Army weapons systems due to their unique material characteristics. They have the potential to provide for enhanced lethality over their conventional munitions counterparts. However, those characteristics are not well defined, particularly the materials' fundamental energy release mechanisms. Through live fire experimental testing of an array of reactive materials consisting of an Al-Ni base, energy release characteristics can be understood on a more scientific level. This is accomplished through the incorporation of customized diagnostic techniques. Test samples of reactive material are fired via a powder gun into a steel-enclosed test chamber fitted with a polycarbonate window for witnessing the event. Raw data from the reaction event is recorded via high speed cameras and oscilloscopes. Analytical tools that are incorporated to characterize the event include pressure measurement gages, high speed imaging, pyrometry, spectroscopy, and flash x-ray. Through a systematic, scientific approach the vast amounts of data collected using these diagnostic tools is then processed into practical information of the reactive material's energy release behavior.

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THz time-domain reflection imaging is utilized as non-destructive evaluation technique for ceramic composite materials in order to characterize changes in material properties due to mechanical and thermal strain effects.