US3806840A - Contoured ultrasonic delay line - Google Patents

Contoured ultrasonic delay line Download PDF

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Publication number
US3806840A
US3806840A US00370196A US37019673A US3806840A US 3806840 A US3806840 A US 3806840A US 00370196 A US00370196 A US 00370196A US 37019673 A US37019673 A US 37019673A US 3806840 A US3806840 A US 3806840A
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US
United States
Prior art keywords
strip
delay line
set forth
thickness
contour
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00370196A
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English (en)
Inventor
D Whitney
R Nepveu
W Gerlach
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Lockheed Martin Corp
Original Assignee
Sanders Associates Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to US00370196A priority Critical patent/US3806840A/en
Application filed by Sanders Associates Inc filed Critical Sanders Associates Inc
Priority to CA194,331A priority patent/CA999655A/en
Priority to IL44424A priority patent/IL44424A/xx
Priority to FR7410519A priority patent/FR2233751A1/fr
Publication of US3806840A publication Critical patent/US3806840A/en
Application granted granted Critical
Priority to DE2420100A priority patent/DE2420100A1/de
Priority to JP49052130A priority patent/JPS5018153A/ja
Priority to IT23342/74A priority patent/IT1012949B/it
Priority to AU69851/74A priority patent/AU6985174A/en
Priority to NO742054A priority patent/NO742054L/no
Priority to SE7407694A priority patent/SE7407694L/
Priority to NL7407916A priority patent/NL7407916A/xx
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/30—Time-delay networks
    • H03H9/36—Time-delay networks with non-adjustable delay time

Definitions

  • FIGES FIGIO CONTOURED ULTRASONIC DELAY LINE BACKGROUND OF THE INVENTION A.
  • This invention relates to delay devices and in particular to solid ultrasonic delay lines.
  • Ultrasonic delay lines are generally operable to provide either a nondispersive or a dispersive delay of continuous wave or pulse type signals.
  • dispersive and nondispersive refer to the delay versus frequency characteristic of a delay line. If delay changes with frequency, the line is said to be dispersive. On the other hand, if the delay is constant, or nearly so, for all frequencies, the line is termed nondispersive.
  • Dispersive delay lines have also been made of wire as evidenced by the article of IE. May entitled Wire Type Dispersive Ultrasonic Delay Lines, IRE Transactions, Volume UE-7, No. 2, June, 1960. While these delay lines do not suffer the loss due to absorbing tape, other problems have been encountered. For example, the very small area of the piezoelectric transducers on wire type dispersive lines have limited their use to relatively low frequencies. In addition, the interference of unwanted modes of propagation have prevented smooth transmission over a wide band of frequencies.
  • an acoustic delay line embodying the present invention is comprised of a strip of ultrasonic transmismension.
  • A is less than one half of the width and is a function of the acoustical frequency and phase velocity of the acoustic waves. Since the phase velocity characteristics of the undesired modes differ from those of the desired mode, the parameter A is generally larger for the unwanted or spurious propagation modes.
  • FIG. 1 is a plan view of a portion of an acoustic delay line embodying the present invention
  • FIG. 2 is a cross sectional view taken along the lines 2-2 of the FIG. 1 delay line;
  • FIG. 3 is a plot of the ratio of phase velocity to transverse velocity versus the frequency and thickness product for an aluminum stripdelay line
  • FIG. 4 is a graph showing exemplary contours for delay lines embodying the present invention.
  • FIG. 5 is aplot of another exemplary contour for a delay line embodying the present invention.
  • FIG. 6 is a plan view of a portion .of a'contoured delay line which is a further embodiment of the invention.
  • FIG. 7 is a cross sectional view taken along the lines 77 of FIG. 6;
  • FIG. 8 is a line graph illustrating the boundaries of wave propagation for different longitudinal modes
  • FIG. 9 is a plan view of a portion of another contoured delay line embodiment of the invention.
  • FIG. 10 is a cross sectional view of the FIG. 9 embodiment.
  • FIGS. 1 and 2 there is shown a portion of a contoured'delay line 20 embodying the present invention.
  • the length, width and heighth of the line 20 extend in the z, y and x'directions, respectively, which directions are depicted at 21 and 22in FIGS. I and 2, respectively.
  • the width W (FIG. 2) is many times greater than the maximum height along the x direction.
  • the line 20 may consist of any'ultrasonic transmission material, it preferably takes the form of an elongated thin strip of aluminum or aluminum alloy.
  • the total length of the'strip is a function of delay required in any desired application.
  • the line thickness is tapered throughout the length of the strip so as to enhance the frequency range over which linear dispersive operation occurs.
  • the propagated energy reaches the transducer at the opposite end, a thickness-longitudinal-mode of vibration is induced therein and converted by the transducer to electrical energy.
  • the electrical and physical connections at each of the ends of the line are similar and therefore either transducer can be used as the input or output, i.e., the line is completely reciprocal.
  • the strip thickness is given a contour in which the maximum thickness occurs at the center of the strip.
  • the contour takes the form of a convex continuous shape in which the maximum thickness occurs at the center line 23 of the strip. Due to the contour, the elastic wave propagation in the z direction is confined to an area which extends a distance A on either side of the center line 23.
  • the reflection angle of an elastic wave between the contoured major surfaces a and 20b is maximum at or near the center line 23 and becomes gradually smaller until at a distance A it becomes zero and reverses itself. That is, the contouring of the major surfaces tends to set up points of reflection at a distance A on either side of the center line 23 so that the propagation of an elastic wave is confined to this region.
  • the distance A turns out to be smaller for wave propagation in the first longitudinal mode M11 than for propagation in the undesired modes M12, M21 and M22.
  • the placement of the edges of a pair of absorber tapes and '26 can be chosen so as to suppress wave propagation in the undesired modes.
  • the lateral or y position of each ray at any instant of time can be expressed as a sine function of the distance along the strip length or -z direction as follows:
  • the longitudinal phase velocity C is larger than the tangeh'fial phase velocity C55 along the sine curve and is related to it in the following way:
  • phase fronts 26 and 27 which intersect at the center line 23 at point 28, be in phase with each other.
  • n A2 the phase fronts 26 and 27 be separated by n A2, where n is any positive integer and A2 C /f and f is the acoustic frequency.
  • the analytic formula for the phase front may be obtained in the following manner. Since, for any value of y, the phase from must be orthogonal to the direction of a ray, the slope of the phase front must be the negative inverse of the slope of the ray. Since the slope of the ray is given by equation (3), the curve zl for the phasefront is given by Assuming that the origin of the coordinate axes 21 coincides with the point 28 in FIG.
  • B can be expressed as follows: 5)
  • the thickness h at any value of y can be related to the center thickness h as follows:
  • FIG. 3 are plotted for Poissons ratio p 0.355, and ff fi s r vlocity C 0Il215iri/ 12sec. Multiplying out the two terms on the right hand side of If Cp in FIG. 3 and in equation (11) is replaced byequation and neglecting terms including 3 and/or C 9, the dependence of C M on thickness for any fre- 5 equation can be Written as follows: quency can be found. Also in FIG.
  • Equations (20) and (2l) basically describe a para- C /f parabolic in shape and independent of the distance A.
  • the points on these curves can be calculated as follows.
  • C is calculated from equation 12) by employing a measured value of the transverse velocity C, 0. l 2 l 5 inches/microseconds.
  • the value of B is calculated from equation (9) with the value of k2 being equal to C /f or 0.0434.
  • equation (21) can be employed to calculate different values of the quantity (1h/h 100 percent for different values of y. I-Iaving once selected a value of B, and thus established a desired contour (e.g., one similar to one of the three curves in FIG. 4) at a midband frequency, it is, of course, desirable to find the values of A at the extremes of the frequency range of interest. The value of A for each new wavelength or frequency is then computed directly from equation (9).
  • the first asymmetric mode M21 has a positive slope in this range and, hence, is subject to the normal beam spreading loss occurring in a flat or uncontoured delay line strip.
  • the reasoning developed above for the M11 mode applies equally to the M22 mode except that the latter mode is asymmetric about the cener y 2 plane.
  • this mode is closely apprc gimated by the inverse relationship given in equation (13).
  • FIG. 5 there is plotted a contour for B 0.268, utilizing equation (21 It is assumed that this contour is to be employed for all sections of a tapered delay line strip, the extreme thicknesses of which are: h 0.0245 and 0.0196 inches.
  • the values of A have been calculated and plotted on the contour for frequency values of 4.3 and 3.7 MHz. for both thickness values in both the M11 and M22 modes, utilizing equations (9), (l2) and (13).
  • equations (9), (l2) and (13) By inspection, it can be seen that all the points representing the A values of the spurious mode M22 lie further from the center line than all the points representing the A values of the desired mode M11. It is therefore possible, by positioning the inside edge of the absorbing tapes 25 and 26 (FIGS.
  • the edge of the absorbing tape 25 or 26 should be placed at a distance of about 0.36 inches from the center of the strip for both of the delay line sections.
  • the edge of the absorbing tape need not be at the same distance from the center line of the strip for different thicknesses thereof.
  • The'contouring of a delay line strip may be accomplished by etching in from the edges of the strip by laydent a1, it may continue to travel in the edge section ing a loosely coiled delay line strip in an empty tank and filling the tank with the etchant at a slow linear rate up to the center line of the strip. The coil is turned over and the operation repeated for the other edge.
  • the transverse taper produced in one example was 0.0003 inches at plus or minus 0.375 inches from the center of the strip.
  • a workable contour can be achieved by rolling 1.75 inch wide and 0.05 inch thick aluminum strip stock through a two high rolling mill which is set for 40 to 50 percent reduction in thickness of the strip and which has a roll diameter of four inches and an axial roll length of six inches.
  • the contour thus achieved can then be measured and plotted to produce a graph similar to that shown in FIG. 5.
  • the values of ,8 and A can then be calculated for the frequency range of interest.
  • the contour need not be continuous by may have discontinuities.
  • the delay line strip portion shown in FIG. 6 has a transverse stepped contour such that the central portion of width Wo has a thickness hl and the two edge sections have a thickness h2 which is smaller than hl.
  • the two edge sections are also covered with absorbing tape 45 and 46.
  • FIGS. 9 and 10 there is illustrated a portion of another delay line strip 51 having a further discontinuous type contour embodying the present invention.
  • this contour the edges of the strip are reduced with a linear taper leaving a flat width W1 in the center of the strip.
  • This type of contour also includes the case where the width of the flat section W1 is reduced to zero. It should be evident that other contours having curvatures somewhat different from the embodiment shown in FIGS. 1, 2, 6, 7, 9 and 10 may be employed so long What is claimed is:
  • a delay line comprising a strip of ultrasonic transmission materialhaving a pair of elongated and generally convex major surfaces to form a contoured cross section with a and means for applying a beam of acoustic waves to said strip whereby acoustic wave propagation between the major surfaces is confined to a region which extends a distance A in both directions from the center of the strip along the width dimension, where A W/2.
  • said beam applying means includes a transducer poled in the longitudinal mode affixed to one end thereof and means for applying electrical signals to said transducer.
  • edges of said absorbing tape means are positioned along the edge sections.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
  • Transducers For Ultrasonic Waves (AREA)
US00370196A 1973-06-14 1973-06-14 Contoured ultrasonic delay line Expired - Lifetime US3806840A (en)

Priority Applications (11)

Application Number Priority Date Filing Date Title
US00370196A US3806840A (en) 1973-06-14 1973-06-14 Contoured ultrasonic delay line
CA194,331A CA999655A (en) 1973-06-14 1974-03-08 Contoured ultrasonic delay line
IL44424A IL44424A (en) 1973-06-14 1974-03-14 Contoured ultrasonic delay line
FR7410519A FR2233751A1 (enrdf_load_stackoverflow) 1973-06-14 1974-03-27
DE2420100A DE2420100A1 (de) 1973-06-14 1974-04-25 Akustische verzoegerungsleitung
JP49052130A JPS5018153A (enrdf_load_stackoverflow) 1973-06-14 1974-05-09
IT23342/74A IT1012949B (it) 1973-06-14 1974-05-30 Linea di ritardo per ultrasuoni avente profilo convesso
NO742054A NO742054L (enrdf_load_stackoverflow) 1973-06-14 1974-06-06
AU69851/74A AU6985174A (en) 1973-06-14 1974-06-06 Delay line
SE7407694A SE7407694L (enrdf_load_stackoverflow) 1973-06-14 1974-06-11
NL7407916A NL7407916A (enrdf_load_stackoverflow) 1973-06-14 1974-06-13

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00370196A US3806840A (en) 1973-06-14 1973-06-14 Contoured ultrasonic delay line

Publications (1)

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US3806840A true US3806840A (en) 1974-04-23

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US00370196A Expired - Lifetime US3806840A (en) 1973-06-14 1973-06-14 Contoured ultrasonic delay line

Country Status (11)

Country Link
US (1) US3806840A (enrdf_load_stackoverflow)
JP (1) JPS5018153A (enrdf_load_stackoverflow)
AU (1) AU6985174A (enrdf_load_stackoverflow)
CA (1) CA999655A (enrdf_load_stackoverflow)
DE (1) DE2420100A1 (enrdf_load_stackoverflow)
FR (1) FR2233751A1 (enrdf_load_stackoverflow)
IL (1) IL44424A (enrdf_load_stackoverflow)
IT (1) IT1012949B (enrdf_load_stackoverflow)
NL (1) NL7407916A (enrdf_load_stackoverflow)
NO (1) NO742054L (enrdf_load_stackoverflow)
SE (1) SE7407694L (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4305159A (en) * 1978-01-23 1981-12-08 Sanders Associates, Inc. Compressive receiver
US5734588A (en) * 1995-01-17 1998-03-31 Electric Power Research Institute Inc. Bore probe for tube inspection with guided waves and method therefor
US6366627B1 (en) 1983-09-28 2002-04-02 Bae Systems Information And Electronic Systems Integration, Inc. Compressive receiver with frequency expansion
US20100058869A1 (en) * 2005-11-04 2010-03-11 Imperial Innovations Limited Ultrasonic non-destructive testing

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH681388A5 (enrdf_load_stackoverflow) * 1989-09-08 1993-03-15 Vaillant Gmbh

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3041556A (en) * 1959-07-01 1962-06-26 Bell Telephone Labor Inc Ultrasonic strip delay line

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3041556A (en) * 1959-07-01 1962-06-26 Bell Telephone Labor Inc Ultrasonic strip delay line

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4305159A (en) * 1978-01-23 1981-12-08 Sanders Associates, Inc. Compressive receiver
US6366627B1 (en) 1983-09-28 2002-04-02 Bae Systems Information And Electronic Systems Integration, Inc. Compressive receiver with frequency expansion
US5734588A (en) * 1995-01-17 1998-03-31 Electric Power Research Institute Inc. Bore probe for tube inspection with guided waves and method therefor
US20100058869A1 (en) * 2005-11-04 2010-03-11 Imperial Innovations Limited Ultrasonic non-destructive testing
US20110016976A1 (en) * 2005-11-04 2011-01-27 Imperial Innovations Limited Ultrasonic non-destructive testing
US8381592B2 (en) * 2005-11-04 2013-02-26 Imperial Innovations Limited Ultrasonic non-destructive testing
US8783110B2 (en) 2005-11-04 2014-07-22 Imperial Innovations Limited Ultrasonic non-destructive testing
US8789419B2 (en) 2005-11-04 2014-07-29 Imperial Innovations Limited Ultrasonic non-destructive testing
US9274090B2 (en) 2005-11-04 2016-03-01 Imperial Innovations Limited Ultrasonic non-destructive testing
US9599593B2 (en) 2005-11-04 2017-03-21 Imperial Innovations Limited Ultrasonic non-destructive testing

Also Published As

Publication number Publication date
DE2420100A1 (de) 1975-01-09
SE7407694L (enrdf_load_stackoverflow) 1974-12-16
AU6985174A (en) 1975-12-11
IL44424A0 (en) 1974-06-30
IL44424A (en) 1976-08-31
CA999655A (en) 1976-11-09
NL7407916A (enrdf_load_stackoverflow) 1974-12-17
IT1012949B (it) 1977-03-10
FR2233751A1 (enrdf_load_stackoverflow) 1975-01-10
JPS5018153A (enrdf_load_stackoverflow) 1975-02-26
NO742054L (enrdf_load_stackoverflow) 1975-01-13

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