The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
L. Wang - One of the best experts on this subject based on the ideXlab platform.
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Time Resolved Line Focus Acoustic Microscopy of Composites
Review of Progress in Quantitative Nondestructive Evaluation, 1999Co-Authors: L. Wang, Stanislav I. Rokhlin, N. N. HsuAbstract:Acoustic Microscopy has been used to measure material properties since the 1980s [1–4]. The velocity of the leaky surface wave can be accurately determined from the V(z) curve which is formed by the interference between the leaky surface wave and specular reflection. By fitting the leaky wave velocity or the V(z) curve itself, Kim et al. [4] reconstructed the material properties (elastic constants and mass density). Another approach is time-resolved Acoustic Microscopy [5–8]. In this method, the leaky surface wave and the specular reflection are separated in the time domain and the velocity is determined from the time of flight. For a graphite/epoxy composite, due to the complexity of the reflected signal and the absence of Rayleigh wave excitation, it is impractical to determine material properties from the V(z) curve. In time-resolved Acoustic Microscopy, the different reflection signals are separated in the time domain and the velocity measurement is simplified. For graphite epoxy composite materials, due to their low density and significant fluid loading, the Acoustic Microscopy response is significantly different from that for higher density materials. To model the time domain Acoustic Microscopy response for a mutilayered composite, we applied the global matrix method in the form similar to that of Mal [9], thus avoiding the numerical instability at high frequency.
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Determination of elastic constants of composites by time-resolved Acoustic Microscopy
Ultrasonics, 1999Co-Authors: L. WangAbstract:By using the angular spectrum Acoustic Microscopy model and the direct global matrix solution for a composite plate, the reflected signal from a time-resolved line focus transducer has been analyzed. The generalized ray solution has been used to decompose the complicated reflected signals into different wave modes. Strategies to determine the elastic constants using time-resolved Acoustic Microscopy have been discussed. Both the lateral wave and the bulk wave reflected from the bottom surface of a composite plate have been used in the elastic constant determination.
G. A. D. Briggs - One of the best experts on this subject based on the ideXlab platform.
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In-situ scanning Acoustic Microscopy of crack bridging in alumina
Journal of The European Ceramic Society, 2003Co-Authors: Thomas James Marrow, G. A. D. Briggs, Steve G. RobertsAbstract:Abstract High-resolution scanning Acoustic Microscopy has been used to observe crack bridging in a fine-grained polycrystalline alumina. The microscope is sensitive to the increased Acoustic transmission across the crack from the interlocking and sliding asperities that cause crack shielding and -curve behaviour. Acoustic Microscopy is found to be more reliable than optical Microscopy for characterising crack bridging. The bridging zone size, bridge density and bridge failure strain are easily determined. The technique may be of considerable use in characterising R-curve mechanisms in a wide range of microstructures.
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Scanning Acoustic Microscopy
Microanalysis of Solids, 1994Co-Authors: P. Mutti, G. A. D. BriggsAbstract:Scanning Acoustic Microscopy is a form of Microscopy based on the generation and detection of elastic waves in solids. The basic mechanism is the interaction of an Acoustic wave with a specimen and the consequent generation of Acoustic waves inside the material. Such interaction is characteristically different from optical or electronic interactions, and is mainly dependent on the mechanical properties of the specimen. As a consequence, Acoustic Microscopy provides an important and complementary source of information for the examination of materials. Two major advantages are obtained using an Acoustic microscope. First, Acoustic waves are capable of penetrating materials that are opaque to other kinds of radiation. As a result, the Acoustic microscope can image subsurface characteristics of materials without the necessity of etching or coating the surface of the sample. The second advantage relies on the origin of contrast in Acoustic Microscopy lying in the interaction of elastic waves with local variations in mechanical properties. Using an Acoustic microscope it is therefore possible to study, with high resolution and sensitivity, mechanical properties of the specimen such as density, elasticity, and viscosity. In the field of material science, applications of Acoustic Microscopy are quite wide and range from the analysis of cracks and other defects in engineering materials to the study of integrated circuits and electronic components. Moreover, recent advances in quantitative Acoustic Microscopy enable the determination of mechanical material parameters on a microscopic scale.
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Acoustic Microscopy of ceramic-fibre composites
1993Co-Authors: C. W. Lawrence, G. A. D. Briggs, C.b. ScrubyAbstract:Scanning Acoustic Microscopy (SAM) has been used to study metal matrix composites (MMCs) reinforced with silicon-carbide monofilaments. For most of the specimens the matrix was Ti-6Al-4V, but Ti3Al and 6061 Al matrices were also examined. The titanium-matrix specimens were subjected to a range of thermal ageing treatments to investigate potential inservice degradation. The main effect was progressive deterioration of the fibre-matrix interface. In the as-received material the carbon-rich coating protected the SiC by forming a reaction layer with the titanium. As a result of ageing, the reaction layer was penetrated adjacent to the β-phase titanium grains. More extensive ageing caused the carbon-rich coating to degrade and eventually disappear. The final stage of deterioration was direct attack on the SiC. Cracks and porosity between fibres were observed in some specimens, probably due to poor diffusion bonding during fabrication. Fine radial microcracks were observed in an annular region inside the mid-radius of some fibres; they are believed to be a consequence of stress relief during thermal ageing. These cracks could not be observed optically. The extra sensitivity of Acoustic Microscopy is due to the reflection of Rayleigh waves by tight closed cracks.
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Time-resolved Acoustic Microscopy of short cracks
1993 Proceedings IEEE Ultrasonics Symposium, 1993Co-Authors: Daniel Knauss, Tongguang Zhai, G. A. D. Briggs, John MartinAbstract:Time-resolved Acoustic Microscopy has been used to measure the 3-dimensional profile of short cracks (70-200 mm surface length). In order to establish this technique the depth of short cracks in transparent materials were determined. This allows a comparison between the Acoustic and direct optical measurements. Subsequently the depth of cracks and the growth of short fatigue cracks in Al-alloy were measured
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Acoustic Microscopy: Pictures to Ponder
Scanning Microscopy, 1992Co-Authors: G. A. D. Briggs, R. Gundle, C. W. Lawrence, A. Rodriguez-rey, C.b. ScrubyAbstract:Applications of Acoustic Microscopy arc growing in various areas of materials and biology. In metal, ceramic, and glass matrix composites the Acoustic microscope enables you to look at the interface between the fibres and the matrix, the formation of cracks in the matrix, and phase transformations. In a particular case of Nicalon (SiC) fibres in a borosilicatc glass matrix, a crystobalite phase was discovered in the matrix, due to devitrification during processing. Different phases have also been identified in rock samples. Biotite, plagioclase, and quartz can be distinguished in granodioritc. In another specimen of this rock, cracks, grain boundaries, and subgrain boundaries can all be seen in the same picture, and the relationships between them studied. In the medical world, Acoustic Microscopy is being used to study the development of the mechanical properties of matrix from bone-derived cells. While the cells are still living, the collaginized and mineralized fibrous structure and its clastic properties can be examined in detail.
J. C. Seferis - One of the best experts on this subject based on the ideXlab platform.
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Characterization of heterogeneous matrix composites using scanning Acoustic Microscopy
Journal of Materials Science, 1993Co-Authors: J. C. SeferisAbstract:Acoustic Microscopy was used to examine the morphology of multi-phase matrices and composites. The Acoustic Microscopy imaging could easily resolve the rubber domains dispersed within a thermosetting or thermoplastic continuous phase. However, because the thermoplastic and thermosetting phase domains had comparable elastic moduli, the resolution between them was not always clear. Rayleigh wave distortion of imaging remained as one of the serious limitations that needed to be overcome in order for this technique to be widely utilized in heterogeneous/anisotropic media. In its present form, the Acoustic imaging technique can be used to augment other existing analytical tools in order to generate more detailed morphological information that is useful in understanding structure-property relationships for multi-phase toughened matrices used in advanced composites.
Гасымова Зиба Вагиф кызы - One of the best experts on this subject based on the ideXlab platform.
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Acoustic Microscopy in orthodontology
Kazan medical journal, 2017Co-Authors: Z V Gasymova, Гасымова Зиба Вагиф кызыAbstract:Aim. Assessment of the possibility to use the method of ultrasound Acoustic Microscopy to control the state of microstructure of hard tooth tissues under the brackets. Methods. The study was conducted with the use of scanning Acoustic microscope ELSAM (Leitz, Germany) in Emanuel Institute of biochemical physics, Moscow. The studied material for Acoustic Microscopy corresponds to 34 teeth (premolars) with brackets fixed to them, which were removed due to orthodontic indications at different time points after brackets placement. Results. In most cases on Acoustic images of the removed teeth there were no revealed changes of physical and mechanical enamel properties, fissures or excess porosity both directly under the brackets and in the areas adjacent to the sealer margin. But in some cases along with good enamel state after long-term brackets placement minor changes in the structure of hard tooth tissues were revealed. In particular, the method of Acoustic Microscopy allowed to detect in the tooth enamel such minor defects as fissures and areas of reduced mineralization and increased porosity. Conclusion. Acoustic Microscopy as a novel method to obtain clear structural images of hard tooth tissue state allows detecting minimal changes of the structure of hard tissues and performing medical interventions based on them.
Vadim Levin - One of the best experts on this subject based on the ideXlab platform.
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Methods of Pulsed Acoustic Microscopy in Industrial Diagnostics
Bulletin of the Russian Academy of Sciences: Physics, 2015Co-Authors: Y. S. Petronyuk, Egor Morokov, Vadim LevinAbstract:A brief review of the methods of pulsed Acoustic Microscopy is presented. The problems and possibilities of nondestructive ultrasonic high-resolution monitoring are discussed. It is shown that methods of pulsed Acoustic Microscopy can be used to control the integrity of multilayer constructions and associated mechanical units. Micron resolution of Acoustic images is attained by focusing the probing ultrasonic beam (50–100 MHz). Original results obtained in joint efforts with developers of 3D miroelectronics and the technology for producing turbine blades are presented.
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The investigation of local piezoelectric properties of piezoelectric transducers by Acoustic Microscopy
IEEE 1988 Ultrasonics Symposium Proceedings., 1Co-Authors: R.g. Mayev, Oleg Kolosov, K.a. Atayev, Vadim LevinAbstract:Local piezoelectric properties of film and plate piezoelectric transducers have been studied by transmission Acoustic Microscopy methods at a frequency of 450 MHz with a resolution of 3 mu m. One-dimensional profiles and gray-scale Acoustic images of the microstructure have been obtained. It is concluded that Acoustic Microscopy can be used effectively for the investigation of the nonmechanical characteristics of piezoelectric transducer specimens. >
