Role of distributed transfer functions for electroacoustic transducers in the metrological security of an ultrasonic inspection

41810 Filimonov, SA. Features of t r a m d u c o r s for r e s o m m t i n s t r u m e n t s for evaluation of the quality of adhesive Joints Soviet Journal of Nondestngtive Testing, Vol. 24. No. 7, 524-528 (1989) The dasigu fentm~ of natrow.lamd ~ are c~midered. Theso are used for resmmnt ultrasonic ~ for evel_u~i/nStile quality of adhesive joints in sheet structures. A comparison is made oftbe frequency characteristicsof the transducers. The advantagex of clmed-type tmmdncen in which the plezoplate is protected with a protector and enclosed in a housing are shown. It is noted that the single-frequuncy design of such ~ r s has made it possible to design the Ad-21R iustnnoent with improved operating parameters. 41776 Antipin, V.E.; Gusarov, V.R.; Perlatov, V.G. Role of distributed transfer f u n c t i o m for eiectruacoustlc t r a n s d u c e r s In the metroiogical security of a n ultrasonic inspection Soviet Journal o f Nondestructive Testing, Vol. 24, No. 8, pp. 532-537 (Apr. 1989) The results are presented of a quantitative study on the intem.,lationabipoftbe field characteristics customm'ily used with direct and inclined electmacoustic transducers, and their distributed tnmsfer functions. It is concluded that the use of distributed transfer functious as the normalized metmloglcal characteristiCS of electruacoustic transducers is preferable.

41650 Pitkanen, J. PVDF contact probes Anglo-Finnish Joint Symposium on Advances in Nondestructive Testing, Espoo (Finland), 9-11 May 1988, pp. 107-128. Edited by T. Astrom. Technical Research Centre of Finland ( v ' r r ) (1988) types of contact probes are discussed in this research. The probes investigated were focussing angle beam probe, normal incidence probe and acoustic emission probe. Some clmracteristics of PVDF foils for probe design am also handled. For the detennimtion of the properties and the behevionr of these PVDF foils two types of probes were calculated with a pmhe design program. Calculated and measured pulses and frequency spectra were compared. The results are in good agreement with the theoretical estimations. Deviations from the theoretical calculations and measurements are discussed. 41629 Forbes, M.J. Tomographic r ~ o m ~ of sound fields of ultrasonic transducers by m e a n s of ~ l l e r e n vimalization techniques DisseaXafion Ala~racts International, Vol. 49, No. 4, p. 1215 (Oct. 1988) A study of uinmamic transducer chanu:terization has been conducted by means of sehllenm imaging, tumographic ~ techniques, and an angular spectrum decomposition method of forward and backward projection. Hunnonic and transient fields of ulummuc transducers have been studied. A method for the forward projection of time- d e i ~ d m Im~tm~ fields into been developed. For the hennonic case it has been shown that the schllen*.nmethod can be a valuable tool in the measuring of ultrasonic fields. Results an= in good agreement with theory and also with the results of other experimentalists. The forward projection technique has allowed complete mapping of n pressure field in both magnitude and phase from a single cross section of optically measured data. 41378 Chou, C-H.; Brutus, TJGY. Design a n d implementation of mixed-mode t r a n s d u c e r s IEF.,E 1~msactions on Ultrasonics, Ferruelectries, and Frequency Control, Vol. 36, No. 3, pp. 33%341 (May 1989) For many applications in m r i a l s ehemcterization acoustic microscopy, and nondestructive evahtafion, it is desirable to generate both longitudinal and shear waves simultenenusly. Prolpefly selected orlentatiom of piezoelectric single crystals or ceramics can he used for this purpose.In order to design a mixed-modetransducer with high efficiency and broad bandwidth for both longitudinal and shear wave modes a theory has been developed to determine the properties of this transducer with asbitr~ acoustic loads at both ends of the piezoelectric element. Several Y-cut lithium niobate ( L ~ s) tramdocon have been made on both single-crystal bismuth germanium oxide (Bil2Gez0) and fused quartz. The piezoelectric plates were attached by indium bonding and later polished to operate in the lO0-kIHz frequency range. The experimental data of round-trip insertion loss for both longitudinal and she,at modes showed an excellent agn~ment with theoretical predictions. 41263 Koyuncu, B. Resonant characterisfles of PZT-4 tramalucers for photo-acoustic signal detection Transducer Teclmology, Voi. 12, No. 5, pp. 17-19 (Feb. 1989) Rectangular snd circular types of PZT-4 tragu~h*~rshave been studied by Kuwait University's Physics Depammnt. Their resonant frequon¢ies were d~rmined in diffenmt media and releted to photo-aconst~ signal generation. Recommendations are made for maximum signal dela~,'tionwith these transducers. 41256 AlersoGA.; Wadley, N.G. Pulsed laser/dectromagnetic a c o u s t k trumalucer approach to ul~nlc smmor needs for steel p r o c a ~ n g National Bureau of Standards (IMSE), Gaithersbmg, Maryland (United States), PB89-1240101, 12 pp. (1987) A lightweight, easily scanned EMAT receiver probe has been cunamcted out of heat resi~lnt materials and samarium cobalt pemmmm magnets to withstand intermittent use at high temporatures. It has been optimized for use with a poised laser ultrasonic source. The sensor was able to detect 1 1 ~ ultrasoul¢ poises generated by a focused 175 millijoule laser pulse with a signal-to-noise ratio of 40:1 (32 dB) on a mild

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steel block with a surfacetem~ratum of 810 deg C. The sensorshowspromisefor the noncon~ct detectionand chamc~rizationof grossinternalporosityin hot steelbodies. 41246 Schafer, M.E. T r a n s d u c e r characterization in Inhomogeneous media using the an. g u t a r s p e c t r u m method Dissertation Abstracts International, Vol. 49, No. 7, pp. 2691 (Jail 1989) A novel technique for analyzing the acoustic fields generated by ultrasonic transmitters when radiating into a layered, inhomngeneous media is presented, hosed on the angular spectrum method of wavefield analysis. Acoustic propagatien between parallel planar surfaces is modelled using the two-dimensional Fourier Transform of the wavefield, witth each element in the spatial fnxluency domain multiplied by the appropriate phase factor. Modifications to the technique were developed to account for the effects of abenwption,dispersion, refraction, and phase distortion. The technique was extended to the widebund pulsed case. An experimental system was built to measure the acoustic fields frmn various transducers, including single element and multi.element phased mTays.The hack-propagation results demonstrate the ability of the extended angular spectrum method to reconstruct the surface velocity distribution of complex acoustic radiators. The forward propagation results illustrate the effects of transmission through layers with different propagation pmperhes. The applications of the method to both the optimization of ultrasonic transducer design and ultrasonic field characterization are demonstrated. 41243 Baboux, J.C.; Jayet, g.; Perdrix, M. Influence of the finite dimension of an ultrasonic t r a n s d u c e r on its transmission a n d reception bchaviour (In French) Institut National des Sciences Appliquees de Lyon, Viileurbsnue (France) PB88-236096/GAR, 137 pp. (1984) In the study, the authors consider the finite lateral dimension of an ultrasonic transducer and study the dimension's effect on the transmission and reception of ultrasonic transducers. A method is presented for calculating the values of certain pmanmers characteristic of ceramics in transmitter piezoelectric disks. A theoretical study and the fabrication of miniature, wide-hand probes for investigating pulsed, ultrasonic fields in liquid media is described. A wide-bend laser interferometer was developed. The device and the probes were used to study the ultrasonic fields radiated by damped transducers the results are presented. An experimental study of the influence of polarization and its uniformity on ultrasonic transducer transmission is described. A study of a longitudinal receiver transducer subjected to different kinds of waves (longitudinal or transverse) of varying incidences is presented. 41225 Hong Zhang Wang; gun He; gi Hong gang. Ultrasound characteristles of focused axlsymmetrically curved surface transducers IEEE Transactions on Ultrasonic, Ferroelectrics, and Frequency Control, Vol. 36, No. 1, pp. 63-72 (Jan. 1989) A high-speed method for exactly calculating the time-dependent pressure of the radiated acoustic field from poise-excited axisymmetrically curved surface or lens transducers is presented. The Rayleigh surface integral is considered to be applicable to curved surface transducers on the basis of experiments. The time-dependont pressure of a medical lens transducer with its outer surface shaped like a revolving-arc is calculated as a main example. Adopting convolution algurithra procedures, the acoustic radiation field has been studied for various forms of exciting pulses. In the calculations, an integral representation of the impulse response function is reduced to a onedimensional (l-D) integration. With the help of the triangle criterion for identification and the pnnciple of one-din~nsional constriction, the calculation may be scanned over the segmented ranges of integration to carry out the numerical analysis. The interrelation of the ultrasound characteristics with some structural aspects of the transducers is thus studied. 41216 Borloo, E.E. PISC round robin test nn the m e a s u r e m e n t of UT i n s t r u m e n t and transducer characteristics (MITC) Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam (Netherlands), 23-28 Apr. 1989, Vol. 2, pp. 1861-1867. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989. PISC, Programme for the Inspection of Steel Components, evaluates perfommnce and reliability of inspection procedures for primary circuit components of nuclear reactors. Parametric studies on equipment characteristics have identified some important parameters that have to be measmed for optimizing inspection techniques. The measurement of these parameters appeared to be performed in different ways by different laboratories. A Round Robin Test on the Measurement of Instrument and Transducer Characteristics has been organized and has shown a large scatter in the measurement results. The reasons for the obtained dispersion will be commented in the proposed presentation. These results are of the highest importance when repeatable measurements are concerned. The results are delivering important indications for regulatory and standardization bodies. 41210 Walte,F.; Gebhardt, W.; Hoffmann, R. NDT of vertical orientated cracks by mode conversion with optimized LLT probes Proceedings of the 12th World Conference on Non-Destructive Testing, Amsterdam (Netherlands), 23-28 Apr. 1989, Vol. 2, pp. 1695-1701. Edited by J. Boogaard and G.M. van Dijk, Elsevier, 1989. An ultrasonic single probe inspection method, basedupon mode conversion, was developedfor the detectionof pot~ndiculady orientedcracks. In comparisonto the cumbersome Tandem technique this q~LT-technique' has about the same sensitivity but has advantages in manual as well as automated inspection with regard to handling and applicability. Besides, the LLT-technique stands out for having an improved accessibility of inspection, a reduced crack inclination dependency and less

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