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Elastic constants of composite materials
ABSTRACTS The a b s t r a c t s survey a p p e a r s in each i s s u e of the journal and e n t r i e s a r e grouped in the following c a t e g o r i e s : Biology and Medicine, Communication and Control; Generation, Detection and Measurement; P h y s i c s ; P r i n c i p l e s and Applications of Effects; P r o c e s s lng and Production; Non-destructive testing; Velocity and Attenuation. A unique number in bold print is placed at the end of each abstract. Copies of o r i g i n a l a r t i c l e s a r e best obtained by writing to the journal in which t h e y a p p e a r ed. The a d d r e s s e s of such journals can be found in r e f e r e n c e books such as 'World L i s t of Scientific and Technical Publications', 'Willings P r e s s Guide', 'Newspaper P r e s s Directory' and, for American journals only, 'AyersL
PRINCIPLES AND APPLICATIONS OF EFFECTS Acousio-electric filter utilizing surfacewave propagation Adler, R. and De Vries A.J. US Patent 3,446,975 (27 M a y 1969) (Filed 7 N o v e m b e r 1966) A tunable solid state acoustic filter comprises a substrate of a piezoelectric material which is also photoconductive. A pair of fixed conductive electrodes on a major surface extend longitudinally with respect to direction of surface-wave propagation. A n optical system is provided for selectively illuminating longitudinally-spaced transversestrip portions of the major surface to establish a conductive transducer electrode pattern whose frequency response is dependent upon the spacings between the i11uminated transverse-strip portions. A n adjustable element, such as a zoom lens on a series of interchangeable transparencies, is provided in the optical system for altering the spacings between the illuminated transversestrip portions to change the frequency response of the filter. (1765) A c r i t i c a l evaluation of the u s e of ultrasonic absorption for determining h i g h - t e m p e r a t u r e ~ properties Ahtyo, F. NASA Technical Note TND-4433 (March 1968) p 45 The usefulness of u l t r a s o n i c absorption for determining the v a l u e s of h i g h - t e m p e r a t u r e gas p r o p e r t i e s has been examined c r i t i c a l l y . The s o u r c e s of u l t r a s o n i c absorption cons i d e r e d are: v i s c o s i t y and t h e r m a l conductivity ( c l a s s i c a l absorption), t h e r m a l r a d i a tion, and relaxation effects due to d i s s o c i a tion, ionization, and electronic excitation by atomic collisions. The absorption values for argon and nitrogen were calculated in an attempt to explain the l a r g e d i s p a r i t y between c l a s s i c a l v a l u e s and those m e a s u r e d by C a r nevale in a s e r i e s of e l e c t r i c arc e x p e r i ments. Ultrasonic absorption in oxygen and in hydrogen was also examined. The calculations show that it i s possible to m e a s u r e the t r a n s p o r t coefficients of argon and hydrogen for two states. The f i r s t o c c u r s when either gas is predominantly in the atomic state. The second state o c c u r s when either gas is mainly c o m p r i s e d of single ions and electrons. The t r a n s p o r t coefficients of nitrogen and oxygen cannot be m e a s u r e d with any degree of accuracy at any t e m p e r a t u r e
because of the masking of the c l a s s i c a l absorption by relaxation effects. The c a l c ul a tions show that the ultrasonic absorption a s sociated with t h e r m a l radiation i s so minute that the absorption technique i s incapable of m e a s u r i n g total ra di a t i ve i n t e n s i t i e s of atmospheric gase s even at t e m p e r a t u r e s sufficiently high that single ionization occurs. The differences between the c l a s s i c a l values of the ultrasoni c absorption and those me a sured by Carnevale can be explained by r e laxation phenomena. For e x a m p l e , t h e anomalous absorption m e a s u r e d in argon is attributed to the finite reaction ra t e for ionization. From this it i s concluded that u l t r a sonic absorption can be used for a c c ura t e l y m e a s u r i n g the predominant ionization ra t e constant of argon. Ionization re l a xa t i on cannot account for the bulk of the anomalous absorption in nitrogen. It i s shown that most of the anomalous absorption can be attributed to collisional excitation of the bound e l e c t r o n s in nitrogen atoms, but only if a high c ol l i sional efficiency e x i s t s . The r e a s o n a b l e n e s s of the required collisionai efficiency cannot be checked at the pre s e nt t i me a s the e xc i t a tion c r o s s sections have not been calculated or m e a s u r e d directly. (1766)
H i g h e r - o r d e r im~_~es reconstructed from a sampled sound-wave hologram Aoki, Y. A sound-wave hologram i s constructed by sampling the acoustic field with a microphone and simulating a re fe re nc e wave e l e c t r o n i cally. Frequency of sound-wave i s chosen as 18kHz and scanning period of microphone as 2.0cm. The optical reconstruction of image from the obtained hologram i s c a r r i e d out using a p a r a l l e l ra y l a s e r light of 6328~ A z e r o - o r d e r image and h i g h e r - o r d e r i m a g e s are r e c o n s t r u c t e d from a g r a t i n g - l i k e soundwave hologram produced by scanning of the microphone. (17671
Elastic constants of composite materials Behrens, E. JASA, Vol 45, N o 1 (January 1969) pp 102-108 Cases of practical interest are considered: Lameilar composites with no particular point symmetry (eg cross plies),filamentary composites with anisotropic constituents (eg graphite composRes), composites with point symmetry 2 / m 2 / m 2/m, and c ompos i t e s with cubic s y m m e t r y . The e l a s t i c constants a r e calculated by evaluating the d i s p e r s i o n r e l a tion of sound waves for long wavelengths.
(1'768)
Ultrasonic modnt~tion of a l a s e r Belova, G. N. Kazantsev, V. F. Soviet Physics--Acoustics, Vol 15, No 1 (JulySeptember 1969) pp 4-9 The effect of ultrasonic o s c i l l a t i o n s on the output of a ruby l a z e r with external m i r r o r s is analyzed. The s t r u c t u r e of the radiation pulse i s investigated for excitation of 40KHz extensional e l a s t i c modes in ruby at constant pumping and v a ri ous oscillation amplitudes. In the e x p e r i m e n t s a r e g u l a r t ra i n of l a s e r radiation pulse s has been obs e rve d at a multiple of the e l a s t i c mode dri vi ng frequency in the c r y s t a l . St a t i s t i c a l p r o c e s s i n g affords a quantitative e s t i m a t e of the e l a s t i c o s c i l l a tions of the c r y s t a l on the radiation of the l a s e r . Several hypotheses a r e offered concerning the mec ha ni s m of the obs e rve d phenomenon. (1789) P h y s i c a l m e c h a n i s m of acoustic atomization of a liquid Boguslavskii Yu. Ya. and Eknadiosyants, O. K. Soviet P h y s i c s - A c o u s t i c s , Vol 15, No 1 (JulySeptember 1969) pp14-21
According to the cavitation-wave hypothesis of the mechanism of liquid atomization in an ul t ra s oni c fountain, a e r o s o l droplets ar e s e pa ra t e d from the c r e s t s of the f i n i t e - a m plitude c a p i l l a r y - w a v e s on the surface of the fountain jet. C a pi l l a ry waves a re produced by periodic shock waves generated by cavitation bubbles inside the jet. E x p e r i m e n t a l proof i s given for the hypothesis, along with an approximate calculation of the p a r a m e t e r s of the shock-wave front formed by cavitation in the jet of a fountain. (1770)
Echo sounding method and a p p a r s i u s Bostroem, H. US Patent 3,439, 318 (15 A pri l 1969) Cont i n u a t i o n - i n - p a r t of application 460, 933 (3 June 1965) D~ring s u c c e s s i v e sounding periods, t r a n s mitted i m p u l s e s have lengths corresponding to a sounding range which is a multiple of the s e l e c t e d sounding range. Only echos r e ceived during a" selected portion of each sound r e c e i v i n g period a re counted. The elapsed time between s u c c e s s i v e sound r e ceiving portions i s m e a s u r e d and s u c c e s s i v e sounding pe ri ods of different r e s p e c t i v e lengths a re used. (1771) Instrument for m e a s u r i n g cavitation intensity in a liquid Branson, N. G. US Patent 3,443,797 (13 May 1969) (Filed 26 November 1965) In o r d e r to m e a s u r e the cavitation intensity in an u l t r a s o n i c a l l y agitated liquid, a piezoe l e c t r i c probe i s i m m e r s e d in the liquid and coupled to a m e a s u r i n g c i r c u i t which p a s s e s s i gna l s in the radio frequency range, substantially above 1MHz. The c i rc ui t includes a balanced bridge and a r e s i s t i v e element which i s heated by the radio frequency s i g n a l s , t h e change of r e s i s t a n c e of the element being indicative of the cavitation intensity. (177~-) Method and device for m e a s u r i n g the t e m perature of a m a t e r i a l by m e a n s of u l t r a sound Centre National de R e c h e r c h e s Metallurgique French Patent 1, 562, 549 (4 April 1969) (Ap(Applied for 26 A pri l 1968) (In Luxembourg 22 May 1967) The device c o n s i s t s of s e v e r a l ul t ra s o n ic t r a n s d u c e r s and a coupling m a t e r i a l between them and the t e s t piece notable in so far as it also has the property of c o m p r e s s i n g the coupling m a t e r i a l on to the t e s t piece to ens ure contact under pressure between them.
(1~7s) Ultrasonic technique for obtaininE v a r i a b l e delay and Doppler shift of m i c r o w a v e s Dobrov, W. I., and Huling, G. E. IEEE T r a n s a c t i o n s on sonics and ul t ra s o n ics , Vol SU-16, No 3 (July 1969) pp102-106 An ul t ra s oni c technique and apparatus for obtaining v a r i a b l e delay t i m e s and Doppler shifts of microwave s i g n a l s a r e described. In o r d e r to v a r y the acoustic path length two p r i s m s a r e employed, one of which s l i d e s with r e s p e c t to the other on a thin l a y e r of a lubricant. This lubricant acts as a dynamic bond for transmission of microwave frequency uRrasonics. The losses due to reflection and absorption in the bonding layer are discussed. Doppler shifts of 1 part in I0 s and delay-time variations of a few microseconds were observed with the apparatus. The device can be used as a variable delay line or as an acoustic simulator of radar echoes. (1774) U L T R A S O N I C S J a n u a r y 1970
63
PRINCIPLES AND APPLICATIONS OF EFFECTS Acousio-electric filter utilizing surfacewave propagation Adler, R. and De Vries A.J. US Patent 3,446,975 (27 M a y 1969) (Filed 7 N o v e m b e r 1966) A tunable solid state acoustic filter comprises a substrate of a piezoelectric material which is also photoconductive. A pair of fixed conductive electrodes on a major surface extend longitudinally with respect to direction of surface-wave propagation. A n optical system is provided for selectively illuminating longitudinally-spaced transversestrip portions of the major surface to establish a conductive transducer electrode pattern whose frequency response is dependent upon the spacings between the i11uminated transverse-strip portions. A n adjustable element, such as a zoom lens on a series of interchangeable transparencies, is provided in the optical system for altering the spacings between the illuminated transversestrip portions to change the frequency response of the filter. (1765) A c r i t i c a l evaluation of the u s e of ultrasonic absorption for determining h i g h - t e m p e r a t u r e ~ properties Ahtyo, F. NASA Technical Note TND-4433 (March 1968) p 45 The usefulness of u l t r a s o n i c absorption for determining the v a l u e s of h i g h - t e m p e r a t u r e gas p r o p e r t i e s has been examined c r i t i c a l l y . The s o u r c e s of u l t r a s o n i c absorption cons i d e r e d are: v i s c o s i t y and t h e r m a l conductivity ( c l a s s i c a l absorption), t h e r m a l r a d i a tion, and relaxation effects due to d i s s o c i a tion, ionization, and electronic excitation by atomic collisions. The absorption values for argon and nitrogen were calculated in an attempt to explain the l a r g e d i s p a r i t y between c l a s s i c a l v a l u e s and those m e a s u r e d by C a r nevale in a s e r i e s of e l e c t r i c arc e x p e r i ments. Ultrasonic absorption in oxygen and in hydrogen was also examined. The calculations show that it i s possible to m e a s u r e the t r a n s p o r t coefficients of argon and hydrogen for two states. The f i r s t o c c u r s when either gas is predominantly in the atomic state. The second state o c c u r s when either gas is mainly c o m p r i s e d of single ions and electrons. The t r a n s p o r t coefficients of nitrogen and oxygen cannot be m e a s u r e d with any degree of accuracy at any t e m p e r a t u r e
because of the masking of the c l a s s i c a l absorption by relaxation effects. The c a l c ul a tions show that the ultrasonic absorption a s sociated with t h e r m a l radiation i s so minute that the absorption technique i s incapable of m e a s u r i n g total ra di a t i ve i n t e n s i t i e s of atmospheric gase s even at t e m p e r a t u r e s sufficiently high that single ionization occurs. The differences between the c l a s s i c a l values of the ultrasoni c absorption and those me a sured by Carnevale can be explained by r e laxation phenomena. For e x a m p l e , t h e anomalous absorption m e a s u r e d in argon is attributed to the finite reaction ra t e for ionization. From this it i s concluded that u l t r a sonic absorption can be used for a c c ura t e l y m e a s u r i n g the predominant ionization ra t e constant of argon. Ionization re l a xa t i on cannot account for the bulk of the anomalous absorption in nitrogen. It i s shown that most of the anomalous absorption can be attributed to collisional excitation of the bound e l e c t r o n s in nitrogen atoms, but only if a high c ol l i sional efficiency e x i s t s . The r e a s o n a b l e n e s s of the required collisionai efficiency cannot be checked at the pre s e nt t i me a s the e xc i t a tion c r o s s sections have not been calculated or m e a s u r e d directly. (1766)
H i g h e r - o r d e r im~_~es reconstructed from a sampled sound-wave hologram Aoki, Y. A sound-wave hologram i s constructed by sampling the acoustic field with a microphone and simulating a re fe re nc e wave e l e c t r o n i cally. Frequency of sound-wave i s chosen as 18kHz and scanning period of microphone as 2.0cm. The optical reconstruction of image from the obtained hologram i s c a r r i e d out using a p a r a l l e l ra y l a s e r light of 6328~ A z e r o - o r d e r image and h i g h e r - o r d e r i m a g e s are r e c o n s t r u c t e d from a g r a t i n g - l i k e soundwave hologram produced by scanning of the microphone. (17671
Elastic constants of composite materials Behrens, E. JASA, Vol 45, N o 1 (January 1969) pp 102-108 Cases of practical interest are considered: Lameilar composites with no particular point symmetry (eg cross plies),filamentary composites with anisotropic constituents (eg graphite composRes), composites with point symmetry 2 / m 2 / m 2/m, and c ompos i t e s with cubic s y m m e t r y . The e l a s t i c constants a r e calculated by evaluating the d i s p e r s i o n r e l a tion of sound waves for long wavelengths.
(1'768)
Ultrasonic modnt~tion of a l a s e r Belova, G. N. Kazantsev, V. F. Soviet Physics--Acoustics, Vol 15, No 1 (JulySeptember 1969) pp 4-9 The effect of ultrasonic o s c i l l a t i o n s on the output of a ruby l a z e r with external m i r r o r s is analyzed. The s t r u c t u r e of the radiation pulse i s investigated for excitation of 40KHz extensional e l a s t i c modes in ruby at constant pumping and v a ri ous oscillation amplitudes. In the e x p e r i m e n t s a r e g u l a r t ra i n of l a s e r radiation pulse s has been obs e rve d at a multiple of the e l a s t i c mode dri vi ng frequency in the c r y s t a l . St a t i s t i c a l p r o c e s s i n g affords a quantitative e s t i m a t e of the e l a s t i c o s c i l l a tions of the c r y s t a l on the radiation of the l a s e r . Several hypotheses a r e offered concerning the mec ha ni s m of the obs e rve d phenomenon. (1789) P h y s i c a l m e c h a n i s m of acoustic atomization of a liquid Boguslavskii Yu. Ya. and Eknadiosyants, O. K. Soviet P h y s i c s - A c o u s t i c s , Vol 15, No 1 (JulySeptember 1969) pp14-21
According to the cavitation-wave hypothesis of the mechanism of liquid atomization in an ul t ra s oni c fountain, a e r o s o l droplets ar e s e pa ra t e d from the c r e s t s of the f i n i t e - a m plitude c a p i l l a r y - w a v e s on the surface of the fountain jet. C a pi l l a ry waves a re produced by periodic shock waves generated by cavitation bubbles inside the jet. E x p e r i m e n t a l proof i s given for the hypothesis, along with an approximate calculation of the p a r a m e t e r s of the shock-wave front formed by cavitation in the jet of a fountain. (1770)
Echo sounding method and a p p a r s i u s Bostroem, H. US Patent 3,439, 318 (15 A pri l 1969) Cont i n u a t i o n - i n - p a r t of application 460, 933 (3 June 1965) D~ring s u c c e s s i v e sounding periods, t r a n s mitted i m p u l s e s have lengths corresponding to a sounding range which is a multiple of the s e l e c t e d sounding range. Only echos r e ceived during a" selected portion of each sound r e c e i v i n g period a re counted. The elapsed time between s u c c e s s i v e sound r e ceiving portions i s m e a s u r e d and s u c c e s s i v e sounding pe ri ods of different r e s p e c t i v e lengths a re used. (1771) Instrument for m e a s u r i n g cavitation intensity in a liquid Branson, N. G. US Patent 3,443,797 (13 May 1969) (Filed 26 November 1965) In o r d e r to m e a s u r e the cavitation intensity in an u l t r a s o n i c a l l y agitated liquid, a piezoe l e c t r i c probe i s i m m e r s e d in the liquid and coupled to a m e a s u r i n g c i r c u i t which p a s s e s s i gna l s in the radio frequency range, substantially above 1MHz. The c i rc ui t includes a balanced bridge and a r e s i s t i v e element which i s heated by the radio frequency s i g n a l s , t h e change of r e s i s t a n c e of the element being indicative of the cavitation intensity. (177~-) Method and device for m e a s u r i n g the t e m perature of a m a t e r i a l by m e a n s of u l t r a sound Centre National de R e c h e r c h e s Metallurgique French Patent 1, 562, 549 (4 April 1969) (Ap(Applied for 26 A pri l 1968) (In Luxembourg 22 May 1967) The device c o n s i s t s of s e v e r a l ul t ra s o n ic t r a n s d u c e r s and a coupling m a t e r i a l between them and the t e s t piece notable in so far as it also has the property of c o m p r e s s i n g the coupling m a t e r i a l on to the t e s t piece to ens ure contact under pressure between them.
(1~7s) Ultrasonic technique for obtaininE v a r i a b l e delay and Doppler shift of m i c r o w a v e s Dobrov, W. I., and Huling, G. E. IEEE T r a n s a c t i o n s on sonics and ul t ra s o n ics , Vol SU-16, No 3 (July 1969) pp102-106 An ul t ra s oni c technique and apparatus for obtaining v a r i a b l e delay t i m e s and Doppler shifts of microwave s i g n a l s a r e described. In o r d e r to v a r y the acoustic path length two p r i s m s a r e employed, one of which s l i d e s with r e s p e c t to the other on a thin l a y e r of a lubricant. This lubricant acts as a dynamic bond for transmission of microwave frequency uRrasonics. The losses due to reflection and absorption in the bonding layer are discussed. Doppler shifts of 1 part in I0 s and delay-time variations of a few microseconds were observed with the apparatus. The device can be used as a variable delay line or as an acoustic simulator of radar echoes. (1774) U L T R A S O N I C S J a n u a r y 1970
63