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Microwave nondestructive testing: theories and applications
N D T Abstracts parameters upon the microwave signals under simplified and well-arranged conditions. Sheets of concrete and bricks were investigated. Transmission and reflection were measured at frequencies of 10, 16 and 36 GHz.
47041 Jackson, J.C.; Ward, G. Surface inspection of steel products using a synthetic aperture microwave technique British Journal of Non-Destructive Testing, Vol. 33, No. 8, pp. 395402 (Aug. 1991) An original approach to the non-destructive evaluation of metal surfaces is described. It is a non-contacting technique based upon microwave scattering, which might be described as a simplified version of synthetic aperture radar. Experimental work at frequencies of 24.125 GHz and 94 GHz is reported. A simple threshold applied to the unprocessed analogue data extracts most of the useful information; however, dramatic improvements in signal-to-noise ratio are effected by a process of deconvolution, which produces a sharp map of surface features. A simple application would be in the in-line inspection of continuously cast billets for transverse cracks.
46342 Wittig,G.; Lingott, H. Microwave investigation of building materials (In G e r m a n :
English Abstract) Materialprufung, Vol. 33, No. 5, pp. 143-144 (May 1991) In civil engineering nondestructive testing means of microwaves in principle is practicable by mason of the interaction of the electromagnetic waves with the materials. Because of the large number of influencing parameters the application, however, is difficlllt and up to now has been restricted to simple problems, it was the object of this investigation to evaluate the effect of separated parameters up on the microwave signals under simplified and well-arranged conditions. Sheets of concrete and bricks were investigated. Transmission and reflection were measured at frequencies of 10, 16 an 36 GHz.
46609 Clemena, G.G. Short-pulse r a d a r methods CRC Handbook on Nondestructive Testing o f Concrete. Edited by V.M. Malhotra and N.J. Carino. pp. 253-274. CRC Press (1991) Short-pulse radar is a powerful scientific tool with a wide range of applications in the testing of concrete. It is gaining acceptance as a useful and rapid technique for nondestructive detection of delaminations and other types of defects in bare or overlaid reinforced concrete decks. It also shows potential for other applications - such as monitoring of cement hydration or strength development in concrete, study of the effect of various admixtures on curing of concrete, determination of water-content in fresh concrete, and measurement of the thickness of concrete members. The physical principles behind short-pulse radar are presented. The advantages and limitations of radar are also discussed.
46608
45578 Zoughi, R.; Vaughan, T. Design and analysis of an a r r a y of square microstrip patches for nondestructive measurement of inner material properties of various structures using swept microwave frequencies Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 23-28 Jul. 1989. Vol. 9B, pp. 11621- 1628. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1990) There are several microwave techniques and probes available for characterizing inner properties of materials. Microstrip patches operating in cavity modes are well suited for determining the dielectric properties of materials. A microstrip patch can be characterized by its resonant frequency and quality factor (Q-factor) when operating in free space. When the patch is covered by another material whose dielectric properties (real and imaginary parts) are different than that of freespace, resonant frequency and Q-factor of the patch will change. Subsequently, the permittivity of the material is related to its moisture content, density, temperature, grain size, etc. via available dielectric mixing models. Such a device can be placed inside a material temporarily (snow pack for avalanche prediction) or permanently (concrete structures for water content and crack detection. The motivation for this effort has been to design an array of microstrip patches to obtain a profile (snow permittivity vs. snow depth) of the inner properties of a material via a single measurement. In designing such an array of the proximity effect of the patches causes undesired field coupling among patches which results in erroneous results. By designing different size patches which resonate at different frequencies, this problem can be alleviated. This paper gives the detailed design of such an array.
Summerscales, J.
Microwave techniques Non-Destructive Testing of Fibre Reinforced Plastics Composites. Vol. 2. Edited by J. Summerscales. pp. 361-412. Elsevier Applied Science (1990) Microwave-frequency electromagnetic energy, usually abbreviated to 'microwaves', interacts with materials in a wave-like manner. Microwaves travel in straight lines, reflect, refract, diffract, scatter and interfere according to the same physical laws as light. Differences in the behaviour am due to the wavelength of microwaves being typically 10 larger than optical wavelengths. Interaction is thus on a macroscopic scale. Microwave NDT techniques are particularly appropriate for the determination of material anisotropy, state-of-cure of the polymer matrix and measurement of the moisture content. It is possible to infer many other physical properties from the microwave techniques, including sample thickness, density, fibre volume fraction, surface mughoess or crazing and detection of voids or inclusions. Recent Soviet work has demonstrated a relationship between the dielectric properties at microwave frequencies and the deformation/strain in the material.
45354 Zoughi, R. Microwave nondestructive testing: theories and applications International Advances in Nondestructive Testing. Edited by W J . McGonnagle. Vol. 15, pp. 255-288. Gordon and Breach (1990) The ability of electromagnetic waves to penetrate most dielectric materials, and their relatively short wavelengths at microwave frequencies make for potential nondestructive applications in this region of the electromagnetic spectrum. It is also possible to produce reasonably sized nondestructive probes that can provide information about the inner structure and characteristics of various types of media. Discussion of some of the techniques and approaches in microwave NDT is presented here.
46591 Kolodii, B2.; Lyashchuk, O~B.;Fedorchak, B2. Radio-wave thickness measurement of planely laminated dielectric materials on the basis of the method of global
minimization Soviet Journal of Nondestructive Testing, Vol. 26, No. 9, pp. 647-650. (May 1991) The article shows numerically and with the aid of full-scale experiments the existence and uniqueness of the solution of the inverse problem of radio-wave thickness measurements of products made of multilayered materials with the use of the method of global minimization.
46590
44841 Zoughi, R.; Lujan, M. Nondestructive microwave thickness measurements of dielectric slabs Materials Evaluation, Vol. 48, No. 9, pp. 1100-1105 (Sep. 1990) This paper discusses two techniques (transmission and reflection) for measuring thickness of dielectric slabs and slabs backed by conducting plates. ~ r e t i c a l and experimental aspects of each technique are outlined in detail along with limitations associated with them. Thickness of plexigiass and synthetic rubber slabs are measured with very good accuracy. The transmission technique is capable also of determining dielectric permittivity of a slab whose thickness is known, making the technique a vc~,atJle one.
Lyashchuk, O.B.
Electromagnetic diagnostics of multilayered polymer materials with defects in the form of delamination Soviet Journal of Nondestructive Testing, Vol. 26, No. 9, pp. 651-656. (May 1991) The method of global minimization is applied to solve problems of radio-wave inspection of the depth of occurrence of delamination in a plate, of checking the thickness of interlaminar delamination, and of defectometry of possible intralaminar and interlaminar delaminatious in a two-layer structure situated on a thick base. Algorithms of the solution are presented, and the obtained numerical results are analyzed.
44840 Bartashevskii, E:L.; Borul'ko, V.F.; Drobakhin, 0.0.; Karlov, VJr.; Slavin, LV. Measuring and computing complex for the radio-wave
46348 Wittig, G.; Lingott, H. Microwave investigation of building materials (In G e r m a n :
inspection of laminated dielectric structures Soviet Journal of Nondestructive Testing, Vol. 25, No. 11, pp. 808-813 (Jul. 1990) The article describes the procedure and the algorithms for the operation
English Abstract) Materialprufung, Vol. 33, No. 4, pp. 106-110 (Apr. 1991) It was the object of this investigation to evaluate the effect of separated
338
NDT&E
International
1994 Volume
27, Number
6
47041 Jackson, J.C.; Ward, G. Surface inspection of steel products using a synthetic aperture microwave technique British Journal of Non-Destructive Testing, Vol. 33, No. 8, pp. 395402 (Aug. 1991) An original approach to the non-destructive evaluation of metal surfaces is described. It is a non-contacting technique based upon microwave scattering, which might be described as a simplified version of synthetic aperture radar. Experimental work at frequencies of 24.125 GHz and 94 GHz is reported. A simple threshold applied to the unprocessed analogue data extracts most of the useful information; however, dramatic improvements in signal-to-noise ratio are effected by a process of deconvolution, which produces a sharp map of surface features. A simple application would be in the in-line inspection of continuously cast billets for transverse cracks.
46342 Wittig,G.; Lingott, H. Microwave investigation of building materials (In G e r m a n :
English Abstract) Materialprufung, Vol. 33, No. 5, pp. 143-144 (May 1991) In civil engineering nondestructive testing means of microwaves in principle is practicable by mason of the interaction of the electromagnetic waves with the materials. Because of the large number of influencing parameters the application, however, is difficlllt and up to now has been restricted to simple problems, it was the object of this investigation to evaluate the effect of separated parameters up on the microwave signals under simplified and well-arranged conditions. Sheets of concrete and bricks were investigated. Transmission and reflection were measured at frequencies of 10, 16 an 36 GHz.
46609 Clemena, G.G. Short-pulse r a d a r methods CRC Handbook on Nondestructive Testing o f Concrete. Edited by V.M. Malhotra and N.J. Carino. pp. 253-274. CRC Press (1991) Short-pulse radar is a powerful scientific tool with a wide range of applications in the testing of concrete. It is gaining acceptance as a useful and rapid technique for nondestructive detection of delaminations and other types of defects in bare or overlaid reinforced concrete decks. It also shows potential for other applications - such as monitoring of cement hydration or strength development in concrete, study of the effect of various admixtures on curing of concrete, determination of water-content in fresh concrete, and measurement of the thickness of concrete members. The physical principles behind short-pulse radar are presented. The advantages and limitations of radar are also discussed.
46608
45578 Zoughi, R.; Vaughan, T. Design and analysis of an a r r a y of square microstrip patches for nondestructive measurement of inner material properties of various structures using swept microwave frequencies Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 23-28 Jul. 1989. Vol. 9B, pp. 11621- 1628. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1990) There are several microwave techniques and probes available for characterizing inner properties of materials. Microstrip patches operating in cavity modes are well suited for determining the dielectric properties of materials. A microstrip patch can be characterized by its resonant frequency and quality factor (Q-factor) when operating in free space. When the patch is covered by another material whose dielectric properties (real and imaginary parts) are different than that of freespace, resonant frequency and Q-factor of the patch will change. Subsequently, the permittivity of the material is related to its moisture content, density, temperature, grain size, etc. via available dielectric mixing models. Such a device can be placed inside a material temporarily (snow pack for avalanche prediction) or permanently (concrete structures for water content and crack detection. The motivation for this effort has been to design an array of microstrip patches to obtain a profile (snow permittivity vs. snow depth) of the inner properties of a material via a single measurement. In designing such an array of the proximity effect of the patches causes undesired field coupling among patches which results in erroneous results. By designing different size patches which resonate at different frequencies, this problem can be alleviated. This paper gives the detailed design of such an array.
Summerscales, J.
Microwave techniques Non-Destructive Testing of Fibre Reinforced Plastics Composites. Vol. 2. Edited by J. Summerscales. pp. 361-412. Elsevier Applied Science (1990) Microwave-frequency electromagnetic energy, usually abbreviated to 'microwaves', interacts with materials in a wave-like manner. Microwaves travel in straight lines, reflect, refract, diffract, scatter and interfere according to the same physical laws as light. Differences in the behaviour am due to the wavelength of microwaves being typically 10 larger than optical wavelengths. Interaction is thus on a macroscopic scale. Microwave NDT techniques are particularly appropriate for the determination of material anisotropy, state-of-cure of the polymer matrix and measurement of the moisture content. It is possible to infer many other physical properties from the microwave techniques, including sample thickness, density, fibre volume fraction, surface mughoess or crazing and detection of voids or inclusions. Recent Soviet work has demonstrated a relationship between the dielectric properties at microwave frequencies and the deformation/strain in the material.
45354 Zoughi, R. Microwave nondestructive testing: theories and applications International Advances in Nondestructive Testing. Edited by W J . McGonnagle. Vol. 15, pp. 255-288. Gordon and Breach (1990) The ability of electromagnetic waves to penetrate most dielectric materials, and their relatively short wavelengths at microwave frequencies make for potential nondestructive applications in this region of the electromagnetic spectrum. It is also possible to produce reasonably sized nondestructive probes that can provide information about the inner structure and characteristics of various types of media. Discussion of some of the techniques and approaches in microwave NDT is presented here.
46591 Kolodii, B2.; Lyashchuk, O~B.;Fedorchak, B2. Radio-wave thickness measurement of planely laminated dielectric materials on the basis of the method of global
minimization Soviet Journal of Nondestructive Testing, Vol. 26, No. 9, pp. 647-650. (May 1991) The article shows numerically and with the aid of full-scale experiments the existence and uniqueness of the solution of the inverse problem of radio-wave thickness measurements of products made of multilayered materials with the use of the method of global minimization.
46590
44841 Zoughi, R.; Lujan, M. Nondestructive microwave thickness measurements of dielectric slabs Materials Evaluation, Vol. 48, No. 9, pp. 1100-1105 (Sep. 1990) This paper discusses two techniques (transmission and reflection) for measuring thickness of dielectric slabs and slabs backed by conducting plates. ~ r e t i c a l and experimental aspects of each technique are outlined in detail along with limitations associated with them. Thickness of plexigiass and synthetic rubber slabs are measured with very good accuracy. The transmission technique is capable also of determining dielectric permittivity of a slab whose thickness is known, making the technique a vc~,atJle one.
Lyashchuk, O.B.
Electromagnetic diagnostics of multilayered polymer materials with defects in the form of delamination Soviet Journal of Nondestructive Testing, Vol. 26, No. 9, pp. 651-656. (May 1991) The method of global minimization is applied to solve problems of radio-wave inspection of the depth of occurrence of delamination in a plate, of checking the thickness of interlaminar delamination, and of defectometry of possible intralaminar and interlaminar delaminatious in a two-layer structure situated on a thick base. Algorithms of the solution are presented, and the obtained numerical results are analyzed.
44840 Bartashevskii, E:L.; Borul'ko, V.F.; Drobakhin, 0.0.; Karlov, VJr.; Slavin, LV. Measuring and computing complex for the radio-wave
46348 Wittig, G.; Lingott, H. Microwave investigation of building materials (In G e r m a n :
inspection of laminated dielectric structures Soviet Journal of Nondestructive Testing, Vol. 25, No. 11, pp. 808-813 (Jul. 1990) The article describes the procedure and the algorithms for the operation
English Abstract) Materialprufung, Vol. 33, No. 4, pp. 106-110 (Apr. 1991) It was the object of this investigation to evaluate the effect of separated
338
NDT&E
International
1994 Volume
27, Number
6