Directional characteristics of receiving-and-radiating ultrasonic transducers

Directional characteristics of receiving-and-radiating ultrasonic transducers

46636 Popko,V.P.: Pitolin, A.l.; Ryabov, G.Y.; Kutyurin, Y.G. Use of piezoelectric ceramic t a m a l e t r a n s d u c e r s in space-time signalproce...

167KB Sizes 3 Downloads 19 Views

46636 Popko,V.P.: Pitolin, A.l.; Ryabov, G.Y.; Kutyurin, Y.G. Use of piezoelectric ceramic t a m a l e t r a n s d u c e r s in space-time signalprocessing a p p a r a t u s Soviet Journal of Nondestructive Testing, Vol. 26, No. 9, pp. 640-646. (May 1991) The increasing use of mosaic piezoelectric ceramic transducers is noted for improving the ¢harnctemtics of various ultramnic methods of inspecting objects having high ultrasonic attenuation. A survey is made of work conducted at the Moscow Power-Engineering Institute on the development and introduction of mosaic transducers that are designed for the temporal and spatial processing of signals in frequency ranges from 100 kHz to IMHz. 46453 Filus,Z.; Malzacher, S. Non-contact t r a n s d u c e r for generation and reception of ultrasonic longitudinal waves IMEKO XI, Theory, Simulations, Calibrations, Testing, Education, Houston, Texas (United States), 16-21 Oct. 1988. pp. 419-440. IMEKO (1989) The paper deals with a non-contact method of generating and receiving ultrasonic longitudinal waves in non-magnetic metals of high conductivity. In this method, called electromagneto-econstic, an electromagnetic field is used to provide coupling between the transducer and the test object. The first part of the paper describes some features of this technique on the basis of theoretical investigation. Next, results of experiments and the design of a small- sized transducer are presented. The effects of frequency and of transducer-to-sample separation as well as directional characteristics are discussed. In the last part of the paper a comparison between electromagneto-acoustic and conventional piezoelectric transducers is made. 46428 Ekis,J.W. Characterization of ultrasonic t r a n s d u c e r s using pattern recognition techniques Allied-Signal Aerospace Co., Kansas City, Kansas (United States), DE91000580/GAR, 15 pp. (Sup. 1990) This paper describes an automated method for characterizing ultrasonic transducers. A computer based test system will collect test data for a given transducer. This data set is then subjected to a pattern recognition algorithm. The results from this classification will place the transducor in a group of similar units. All the transducers in a group will have similar performance characteristics. 46410 Shevaldykin, V.G.; Yakovlev,N.N.: Kozlov, V.N. Ultrasonic iow-froquency piezoelectric t r a n s d u c e r s Soviet Journal of Nondestructive Testing, No. 26, Vol. 6, pp. 405-410 (Feb. 1991) Design features am described and basic electruacoustic characteristics am presented for ultrasonic low-frequency piezoelectric transducers that have a low level of intrinsic acoustic noise noise and that are intended for the inspection of objects make of large.structural materials using the pulsed echo-method.

46409 Duldier, V.N.; Belov, G.V.; Allaverdiev, A.M.; Shmakova, T.N. Directional characteristics of receiving-and-radiating ultrasonic transducers Soviet Journal of Nondestructive Testing, No. 26, Vol. 6, pp. 411-415 (Feb. 1991) A study is made of bow a completely internal reflection affects the receiving and radiating characteristics of ultrasonic transducers. The reasons are analyzed for the generation of piezoelectric voltage at angle of incidence for sound waves that exceed the critical angle of complete internal reflection.

46140 lvanov,V.I.; Mirgazov, V.A. Numerical modeling of pulse-signal transmission through acoustic transducers Soviet Journal of Nondestructive Testing, Voi. 26, No. 5, pp. 308-314 (Dec. 1990) A numerical analysis is carried out for the transmission of pulse signals through acoustic tmusducers that have various amplitude- frequency characteristics. In a number of cases the parameters of the output signal were found to he nonmonntonic functions of the input- signal parameters. 45901 Be:mink, D.D.; Pate, A.L. Characterization of ultrasonic immersion t r a n s d u c e r s Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 23-28 Jul. 1989. Vol. 9A, pp. 781- 788. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1990) In this paper, we first derive a quick and efficient method for calculating the field radiated by a finite but otherwise arbitrary velocity profile. Then we develop a transducer characterization method by expanding the transducers velocity profile in a set of orthonormal basis functions. The coefficients in this expansion are obtained by using a singular value decomposition method along with additional constraints imposed on the profile. Some representative numerical results are presented to support the validity of this approach.

45898 Posakony,G.J.; Green, E.R. Performance of a b r o a d h a n d e d ultrasonic t r a n s d u c e r with coaxiallymounted, nondirectional receiver Review of Progress in Quantitative Nondestructive Evaluation, Brunswick, Maine (United States), 23-28 Jul. 1989. Vol. 9A, pp 807- 814. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1990)

N D T & E International Volume 25 Number 3 1992

It is well established that the amount of energy and the directivity panems reflected from a target (flaw or defect) are highly dependent on the type and shape of the target. Further, it is known that the din~ivity pattern of the receiving tranaducer can inhibit the ability to characterize the target. To study these effects, an experiment was designed using a nondirectional receiver, cuaxially-mounted into the transmitting element. The objective was to demonstrate the influence of directionality as it relates to target orientation and size. 45871 Paul,M.A. T r a n s d u c e r effects on ultrasonic attenuation measurements Ames Laboratory, Iowa (United States), DEg0011738/GAR, 155 pp. (Feb. 199O) This paper discusses attenuation measurements, transducer characterization and the effect of transducer characterization and the effect of transducer characterization on attenuation measurements. 45858 Richter, K.P.; Reibold, R.; Molkenstruck, W. Sound field characteristics of ultrasonic composite pulse t r a n s d u c e r s Ultrasonics, VoL 29, No. 1, pp. 76-80 (Jan. 1991) The present paper deals with the dynamic behaviour of broadband composite transducers, with particular emphasis on sound field properties affected by lateral resonance effects. Besides admittance and transfer function mealsurements a highresolution aconsto-optic technique is also used which makes detailed insight into the sound field structure possible. 45403 Grewe,M.G.; Gururaja, T.R.; Shrout, T.R.; Newnham, R.E. Acoustic properties of particle/polymer composites for ultrasonic t r a n s d u c e r backing applications IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency conU'ol, Vol. 37, No. 6, pp. 506-514 (Nov. 1990) The acoustic impedance and attenuation in composites made of particle fillers loaded in polymer matrices for transducer backing applications is explored. The acoustic impedance of tungsten/vinyl composites was modeled and an experimental matrix identifying variables that contribute to composite attenuation was established. The variables included the particle type, the particle size and volume fraction of a filler, the physical characteristics of the polymer matrix, and the processing mute that detem',ioed the composite connectivity. Experimental results showed that with an increase in filler particle size or a decrease in volume fraction of filler, there is an increase in composite attenuation.

Saporito,M.; Lewis, P.; Ammirator, F.; Kietzman, K.; Willetts, 1".; Clayton, W.


Examination of G i n n a pressure vessel nozzle welds using focussed probes Nuclear Plant Journal, Vol. 8, No. 6, pp. 64, 66-67 (Nov.-Dee. 1990) A 10 year in-service inspection (ISI) of the reactor pressure vessel was completed recently at Rochester Gas & Electric's (RG&E) R. E. Ginua plant using specialized focussing ultrasonic pmhes for examining the nozzle-to-shell welds from the nozzle bore. This is believed to be the first nozzle weld examination using focussed probes in the United States. A flaw in an inlet nozzle-twsbell weld was detected during the actual ISI and was sized with these techniques. The accurate sizing capability allowed the flaw to be characterized reliably in a manner acceptable to the regulatory authorities. 45367 Pangraz,S.; Arnold, W. PVDF-transducers and their use in NDE of engineering ceramics Ultrasonic Signal Processing, International School of Physical Acoustics, Erice (Italy), 20-30 Oct. 1988. pp. 451-462 Edited by A. Alippi World Scientific (1989) I S B N 9 971 50 8648 PVDF transducers exhibit a broad bandwidth because the piezoelectric constant can have a gradient inside the material and it is also determined by the electrical matching network employed. A broadband characteristic can be obtained by matching the impedance with an inductance and by transforming the value of the effective impedance to 50 ohms with a tomidal transformer. Experimentally, we achieved an insertion loss of about 20 dB for a 35 MHz-PVDF-trausducer, its 3 dB bandwidth being about 17 MHz. For Polyvinylidena Trifiuorethyleoe P(VDF-TrFe), a copolymer of PVDF, the insertion loss is about 10 dB rivalling the one obtainable with PZT-transduoers. These transducers are well suited for defect-detection in ceramics. In ceramic components we have found defects with sizes down to 30 mum in a depth of 3 mm and with a signai/noise-retio of 6 dB. 44716 Dombret,P. Effect of defect characteristics on immersion focussing probe testing results final report EUR 12433 EN, 22 pp. (1989) The results of the Round-Robin trails conducted under the PISC 1 exercise (1976-1980) showed large discrepancies in the defect detection and sizing capability among different flaws. To identify the causes of such dispersions a number of steel specimens containing various artificial defects was made available for measurement. The defects were ultrasonically scanned by standard methods and by some advanced techniques, the high performance of which had been established in the PISC Round Robin Tests. This report deals with the beam focussing technique: 2 MHz 45 ° shear wave transducers have been used in immersion to collect the signals generated by the reference reflectors. The results show that the depth and the size of a defect do not affect significantly it detection and sizing, provided that the natural variation of sensitivity and of beam diameter along the propagation axis is taken into account. On the other hand, parameters such as the orientation and the roughness modify the conditions of impact and interference of the acoustic beam with the defect surface, and therefore strongly influence the energy pan'ition in diffracted and specolafly reflected rays.