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38686 Wave propagation in fiver reinforced composites for oblique incidence
including a normal beam longitudinal wave high frequency area ratio feature mapping (F-map) system, oblique incidence shear wave amplitude F-maps, and plate leaky wave amplitude F-map remits for interracial weakness in an adhesive bond structure. Also discussed are the results from a normal beam longitudinal wave amplitude and frequency bandwidth F-map for crack detection in a composite material, as well as a backseattered energy F-map for defect edge detection in composite materials. 38746
Gundtoft, H.E.
Ultrasonic examination of ceramics and composites for porosities in an automatic scanning system Riso National Laboratory, Roskilde ( D e n m a r k ) , RISO-M-2711, 16 pp. (May 1988) Using a very precise scanning system and computer evaluation, quantitative results may be obtained from automatic ultrasonic examination. In this paper two examples dealing with nonmetallic materials are presented. In a ceramic plate small spherical pores would harm the final product. Several artificial defects made in the plate were used for calibration and optimisation of the technique. Areas with natural defects were viewed with a microscope. Good agreement with the predicted values from the ultrasonic examination was found. Carbon-reinforced composites were examined. Air trapped in the material resulted in pores in the final product. A double trough transmission-scanning technique was used for the examination. The porosity percentages were determined by the NDT-technique, and agreement with destructively determined values on samples from the same sheet was found. 38692 Nayfeh, A.H.; Chimenti, D.E. Propagation of guided waves in fluid-coupled plates of fiber-reinforced
composite Journal of the Acoustical Society of America, Vol. 83, No. 5, pp. 1736- 1743 (May 1988) Guided wave propagation in fluid-coupled plates of fiber-reinforced composites has been investigated by studying ultrasonic reflection in these structures. From measurements of ultrasonic reflection on unidirectional graphite-epoxy plates over a range of incident angles, experimental dispersion curves using a total-transmission criterion for leaky plate waves have been constructed. Theoretical calculations with no adjustable parameters demonstrate excellent agreement with the experimental data. Unusual behavior observed in the fundamental total- transmission curve led to a reexamination of the mode identification criteria. Both the total-transmission curves and the normal modes of the fluid-coupled plate differ significantly from the result expected on the basis of the widely used Cremer coincidence condition to identify propagating plate waves. It is found that these differences are particularly pronounced in cases where the ratio of fluid to solid densities is high, as for composite materials. The existence of such behavior is also demonstrated numerically in a flnid-coupled aluminum plate by arbitrarily increasing the density of the fluid.
Journal of Composite Materials, Vol. 22, No. 3, pp. 287-303 (Mar. 1988) Ultrasonic testing is widely used for quality assurance of advanced composite materials and usually involves an immersion C-Scan procedure. In this paper, a simplified method is developed for analyzing reflection-refraction phenomena in transversely isotropic materials for arbitrary angles of incidence, implemented on a laboratory microcomputer. Oblique angles of incidence can he used in composites as well as isotropic media, with the same mode conversion techniques. Scanning mode may be used to expose local variations in orthotropic moduli. 38664
Tittmann, B.
Advanced processing of composites M R S Bulletin, Vol. 13, No. 4, pp. 21-26 (Apr. 1988) The pre-eminence of the U.S.A. in aeronautics can only be maintained through advances in material science and engineering especially nondestructive testing. Cost-effective, high quality processing technology, such as real time on-line process control systems using artificial intelligence and advanced sensors will be necessary to complement these developments. One example is described and its functions explained. 38634
Smith, R.L.
NDT applied to new materials New Materials and their Applications, 1987. Proceedings of T h e Institute of Physics Conference, Warwick (United Kingdom), 22-25 Sep. 1987. pp. 251-254. Edited by S.G. Burnay. I O P P , 325 pp., 1988. I O P Conf. Series No. 89. A considerable range of NDT techniques is now available for the inspection of well-established constructional materials. However, new materials now being pressed into service in a range of industries have significantly different properties and require modified or new testing techniques. This paper discusses these requirements and some of the methods available and under development to meet them. 38504
Qu Jianmin
Backscatter from flaws in fiber-reinforced composites
Wave propagation in fiber reinforced composites for oblique incidence
Dissertation Abstracts International, Voi. 48, No. 8, pp. 2377-2378 (Feb. 1988) This thesis consists of two parts. The first part deals with wave scattering by cracks in anisotropic elastic media. A slit, as well as a penny-shaped crack in a transversely isotropic solid, are considered. A new method of asymptotic analysis based on the integral representation for the scattered field is formulated to solve scattering by a planar crack in materials with a more general kind of anisotropy. The second part of this thesis is concerned with detection and characterization of flaws in composite plates by ultrasonic means. A range of wavelengths is selected so that the mechanical behavior of the inhomogeneous fiber-reinforced composites can be represented by that of a homogeneous but anisotropic elastic solid. It is anticipated that the backscatter analysis will prove useful in the non-destructive characterization of flaw sizes, attenuation coefficients and the density of porosity of composite materials.
Each entry in N D T Abstracts consists of the serial number in the National N D T Centre Information Store for identification purposes; the title of the paper, book or report; the name of the author; the name of the source journal or document and the abstracts. Where necessary, a u t h o r ' s names and the title of foreign journals have been transliterated into the Latin alphabet according to British Standard BS 2979:1958.
Information Service, US Department of Commerce, Springfield, Virginia 22151, USA. British and foreign standards can be obtained from Sales Department, British Standards Institution, 101 Pentonville Road, London N1 9ND; and British and foreign patents from the Patents Office Sales Branch, Block C, Station Square House, St Mary Cray, Orpington, Kent BR5 3RD.
Availabifity of Publications
Information-retrieval Service
Most papers listed m a y be obtained as loans or copies via a local library or direct from Loans Department, British Library Document Supply Centre, Boston Spa, Wetherby, Yorkshire LS23 7BQ. Details of the British Lending Library's U K and International Services m a y be obtained from The Director, British Library Lending Division. Technical reports are also available from the Loans Department of the British Lending Library and in the USA from the National Technical
All entries are indexed in a computerized retrieval system, located at Harwell, which allows rapid searching of information relevant to any particular inspection problem. This service is available to both U K and overseas organizations through the National N D T Centre's Qualtis Subscriptions S c h e m e - further details are available from Phil Lawrence on Abingdon (0235) 433391.
38686
Kline, R.A.
NDT International August 1990
© 1990 United Kingdom Atomic Energy Authority
237
Gundtoft, H.E.
Ultrasonic examination of ceramics and composites for porosities in an automatic scanning system Riso National Laboratory, Roskilde ( D e n m a r k ) , RISO-M-2711, 16 pp. (May 1988) Using a very precise scanning system and computer evaluation, quantitative results may be obtained from automatic ultrasonic examination. In this paper two examples dealing with nonmetallic materials are presented. In a ceramic plate small spherical pores would harm the final product. Several artificial defects made in the plate were used for calibration and optimisation of the technique. Areas with natural defects were viewed with a microscope. Good agreement with the predicted values from the ultrasonic examination was found. Carbon-reinforced composites were examined. Air trapped in the material resulted in pores in the final product. A double trough transmission-scanning technique was used for the examination. The porosity percentages were determined by the NDT-technique, and agreement with destructively determined values on samples from the same sheet was found. 38692 Nayfeh, A.H.; Chimenti, D.E. Propagation of guided waves in fluid-coupled plates of fiber-reinforced
composite Journal of the Acoustical Society of America, Vol. 83, No. 5, pp. 1736- 1743 (May 1988) Guided wave propagation in fluid-coupled plates of fiber-reinforced composites has been investigated by studying ultrasonic reflection in these structures. From measurements of ultrasonic reflection on unidirectional graphite-epoxy plates over a range of incident angles, experimental dispersion curves using a total-transmission criterion for leaky plate waves have been constructed. Theoretical calculations with no adjustable parameters demonstrate excellent agreement with the experimental data. Unusual behavior observed in the fundamental total- transmission curve led to a reexamination of the mode identification criteria. Both the total-transmission curves and the normal modes of the fluid-coupled plate differ significantly from the result expected on the basis of the widely used Cremer coincidence condition to identify propagating plate waves. It is found that these differences are particularly pronounced in cases where the ratio of fluid to solid densities is high, as for composite materials. The existence of such behavior is also demonstrated numerically in a flnid-coupled aluminum plate by arbitrarily increasing the density of the fluid.
Journal of Composite Materials, Vol. 22, No. 3, pp. 287-303 (Mar. 1988) Ultrasonic testing is widely used for quality assurance of advanced composite materials and usually involves an immersion C-Scan procedure. In this paper, a simplified method is developed for analyzing reflection-refraction phenomena in transversely isotropic materials for arbitrary angles of incidence, implemented on a laboratory microcomputer. Oblique angles of incidence can he used in composites as well as isotropic media, with the same mode conversion techniques. Scanning mode may be used to expose local variations in orthotropic moduli. 38664
Tittmann, B.
Advanced processing of composites M R S Bulletin, Vol. 13, No. 4, pp. 21-26 (Apr. 1988) The pre-eminence of the U.S.A. in aeronautics can only be maintained through advances in material science and engineering especially nondestructive testing. Cost-effective, high quality processing technology, such as real time on-line process control systems using artificial intelligence and advanced sensors will be necessary to complement these developments. One example is described and its functions explained. 38634
Smith, R.L.
NDT applied to new materials New Materials and their Applications, 1987. Proceedings of T h e Institute of Physics Conference, Warwick (United Kingdom), 22-25 Sep. 1987. pp. 251-254. Edited by S.G. Burnay. I O P P , 325 pp., 1988. I O P Conf. Series No. 89. A considerable range of NDT techniques is now available for the inspection of well-established constructional materials. However, new materials now being pressed into service in a range of industries have significantly different properties and require modified or new testing techniques. This paper discusses these requirements and some of the methods available and under development to meet them. 38504
Qu Jianmin
Backscatter from flaws in fiber-reinforced composites
Wave propagation in fiber reinforced composites for oblique incidence
Dissertation Abstracts International, Voi. 48, No. 8, pp. 2377-2378 (Feb. 1988) This thesis consists of two parts. The first part deals with wave scattering by cracks in anisotropic elastic media. A slit, as well as a penny-shaped crack in a transversely isotropic solid, are considered. A new method of asymptotic analysis based on the integral representation for the scattered field is formulated to solve scattering by a planar crack in materials with a more general kind of anisotropy. The second part of this thesis is concerned with detection and characterization of flaws in composite plates by ultrasonic means. A range of wavelengths is selected so that the mechanical behavior of the inhomogeneous fiber-reinforced composites can be represented by that of a homogeneous but anisotropic elastic solid. It is anticipated that the backscatter analysis will prove useful in the non-destructive characterization of flaw sizes, attenuation coefficients and the density of porosity of composite materials.
Each entry in N D T Abstracts consists of the serial number in the National N D T Centre Information Store for identification purposes; the title of the paper, book or report; the name of the author; the name of the source journal or document and the abstracts. Where necessary, a u t h o r ' s names and the title of foreign journals have been transliterated into the Latin alphabet according to British Standard BS 2979:1958.
Information Service, US Department of Commerce, Springfield, Virginia 22151, USA. British and foreign standards can be obtained from Sales Department, British Standards Institution, 101 Pentonville Road, London N1 9ND; and British and foreign patents from the Patents Office Sales Branch, Block C, Station Square House, St Mary Cray, Orpington, Kent BR5 3RD.
Availabifity of Publications
Information-retrieval Service
Most papers listed m a y be obtained as loans or copies via a local library or direct from Loans Department, British Library Document Supply Centre, Boston Spa, Wetherby, Yorkshire LS23 7BQ. Details of the British Lending Library's U K and International Services m a y be obtained from The Director, British Library Lending Division. Technical reports are also available from the Loans Department of the British Lending Library and in the USA from the National Technical
All entries are indexed in a computerized retrieval system, located at Harwell, which allows rapid searching of information relevant to any particular inspection problem. This service is available to both U K and overseas organizations through the National N D T Centre's Qualtis Subscriptions S c h e m e - further details are available from Phil Lawrence on Abingdon (0235) 433391.
38686
Kline, R.A.
NDT International August 1990
© 1990 United Kingdom Atomic Energy Authority
237