US3543059A - Fluted cylinder for underwater transducer - Google Patents

Fluted cylinder for underwater transducer Download PDF

Info

Publication number
US3543059A
US3543059A US771224A US3543059DA US3543059A US 3543059 A US3543059 A US 3543059A US 771224 A US771224 A US 771224A US 3543059D A US3543059D A US 3543059DA US 3543059 A US3543059 A US 3543059A
Authority
US
United States
Prior art keywords
cylinder
staves
transducer
underwater transducer
diameter
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
US771224A
Inventor
Wesley L Angeloff
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.)
US Department of Navy
Original Assignee
US Department of Navy
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
Application filed by US Department of Navy filed Critical US Department of Navy
Application granted granted Critical
Publication of US3543059A publication Critical patent/US3543059A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/72—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using ultrasonic, sonic or infrasonic waves

Definitions

  • FIG. 2 FLUTED CYLINDER FOR UNDERWATER TRANSDUCER Filed QCE. 28, 1968 FIG. 2
  • Cylinders of electroacoustic material such as piezoelectric ceramic or magnetostrictive or electrostrictive metals are currently employed because, when freeflooded, they can be operated at any depth, inasmuch as the hydrostatic pressure is equalized at all parts of the cylinder.
  • the lowest natural resonant frequency of a cylinder is a function of the stiffness which in turn is a function of wall thickness and diameter of the cylinder and cannot be economically reduced below a fairly high value without increasing the diameter to unwieldy dimensions.
  • there is a definite limit to the minimum wall thickness to get compliance because of the inherent weakness of most ceramics.
  • the objects of this invention are obtained by con structing the cylindrical transducer of staves of the electroacoustic material which staves are joined edge-to-edge to form the cylinder.
  • the staves, or slats are irregular in cross section, so that when they are joined edge-to-edge, the length of the circumferential path in the cylinder is greater than the mean circumferential diameter of the cylinder. It follows that the ratio of mean diameter to thickness is increased so that compliance and the natural frequency of resonance of the cylinder is correspondingly decreased.
  • the principal object of this invention is to produce an improved cylindrical transducer which will operate efliciently at lower frequencies.
  • a more specific object of this invention is to lower the mechanical resonant frequency of a cylindrical transducer.
  • FIG. 1 is a perspective view of one cylindrical transducer of this invention.
  • FIG. 3 is an end view of a cast metal cylinder of this invention.
  • the cylinder 10 shown in FIG. 1 is fabricated of staves 12.
  • the staves 12 are relatively long, narrow slats of electroacoustic material and are joined edge-to-edge by adhesives or solder. If each stave is a piezoelectric ceramic, the soldered junctions 14 may contain connections 16 to the signal circuit.
  • the ceramic is of a barium titanate or lead zirconate titanate and preferably is polarized during manufacture by electrodes of opposed potential along opposite edges of the slats. Alternate electrodes in the cylinder are connected together and to external circuits. The external circuits may lead to either a transmitter or a receiver.
  • the staves 12, in FIG. 1 are irregular in cross section, the irregularity comprising a radius of curvature, R which is less than the mean radius of, R the cylinder.
  • the concaved sides of the slats can each be oriented toward the inside of the cylinder as suggested in FIGS. 1 or 3, or toward the outside of the cylinder as suggested in FIG. 2, or the concavity may alternate among these slats as shown in FIG. 4. It follows that the length of the circumferential path through the electroacoustic material is greater than in a cylinder of the same mean diameter with a smooth wall.
  • the natural mechanical resonant frequency, at which the cylinder will operate is proportional to the stiffness or compliance of the cylinder which in turn is a function of the ratio of the diameter of the cylinder to the wall thickness of the cylinder, water loaded. That is, as the diameter, and the circumferential length of the cylinder wall are increased for a given wall thickness, the natural resonant frequency decreases.
  • the order of magnitude of this ratio found to be practical in sea operations, is about 30 to 1. If the diameter to wall thickness is still further increased, the end result approaches that of a paper-thin tube or wet noodle which of course is mechanically unfeasible. For most ceramics, at present in use in this art, the ratio of diameter to wall thickness should not substantially exceed 30 to 1.
  • metal may be used. Motion in the cylinder wall as a function of signal voltages may now be produced by magnetostriction. If the cylinder is of sheet nickel or other ferromagnetic metals, the signal can be inductively coupled to the cylinder, as suggested, for example, in the US. patent to Green, No. 3,177,382, issued Apr. 6, 1965. In fabricating such a transducer 22, FIG. 3, a single sheet of metal could be rolled with integral side-by-side flutes and the cylinder then closed with a single seam.
  • Still another technique of construction found to be satisfactory comprises casting the fluted cylinder. More specifically, metal can be vaporized in an electric arc and blown onto a form of the desired shape. As shown in FIG. 3, the metal layer 24 is sprayed on the split cylindrical form 22.
  • the discrete metal particles of the layer 24 are quite small and densely packed, and can be laid down in layers which will have low eddy current losses, and yet can have a high coeflicient of expansion per unit of signal voltage.
  • the voltage gradient preferably is applied by conductors wound around. the laminated coating.
  • a cylindrical transducer comprising:
  • electrodes contacting each stave to functionally resaid staves comprising a sheet of magnetostrictive late signal voltages on the electrodes and physical 5 metal.
  • the piezoelectric material of said staves being said cylinder comprising magnetostrictive metal cast so selected and polarized and the electrodes on each to the mentioned shape of said staves.
  • stave being so .disposed that said physical distortion is principally expansion and contraction between 10 Refelfrellces Cited the side edges of said staves to cause radial displace- UNITED STATES PATENTS ment of the wall of said cylinder,
  • said staves being circular in cross-section between the gf ig 'f g'g'g joints, the radius of curvature of said cross section 2521136 9/1950 Thuras being uniform and less than said mean radius of 5 3302163 1/1967 A d the cylinder for increasing the length of the path n ⁇ ews 3 142 035 7/1964 Harris 3108.6 XR 1n the wall, circumferentially oi the cyllnder, beyond 2515446 7/1950, Gravley 310 9 6 XR the clrcumference corresponding to said predeter- 3,177,382 4/1965 Green 310 9'6 XR mined mean radius for lowering the natural me- :chanical resonant frequency of said cylinder, the 20 MILTON HIRSHFIELD Primary Examiner thickness, curvature and width of said staves being selected to stiffen the cylinder and prevent flexure in REYNOLDS: Assistant Exammel' the walls of the cylinder.
  • staves comprising piezoelectric ceramics of the a 3109.6, 26; 340-10

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Description

NOV. 24, 1970 w. ANGELQFF 3,543,059
FLUTED CYLINDER FOR UNDERWATER TRANSDUCER Filed QCE. 28, 1968 FIG. 2
INVENTOR WESLEY L. ANGELOFF ATTORNEYS United States Patent O 3,543,059 FLUTED CYLINDER FOR UNDERWATER TRANSDUCER Wesley L. Angelolf, San Diego, Calif., assignor to the United States of America as represented by the Secretary of the Navy Filed Oct. 28, 1968, Ser. No. 771,224 Int. Cl. H02k 7/00 US. Cl. 310-8.7 4 Claims ABSTRACT OF THE DISCLOSURE STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
BACKGROUND OF THE INVENTION Cylinders of electroacoustic material such as piezoelectric ceramic or magnetostrictive or electrostrictive metals are currently employed because, when freeflooded, they can be operated at any depth, inasmuch as the hydrostatic pressure is equalized at all parts of the cylinder. Unfortunately, the lowest natural resonant frequency of a cylinder is a function of the stiffness which in turn is a function of wall thickness and diameter of the cylinder and cannot be economically reduced below a fairly high value without increasing the diameter to unwieldy dimensions. Likewise, there is a definite limit to the minimum wall thickness to get compliance because of the inherent weakness of most ceramics.
SUMMARY OF THE INVENTION The objects of this invention are obtained by con structing the cylindrical transducer of staves of the electroacoustic material which staves are joined edge-to-edge to form the cylinder. The staves, or slats, are irregular in cross section, so that when they are joined edge-to-edge, the length of the circumferential path in the cylinder is greater than the mean circumferential diameter of the cylinder. It follows that the ratio of mean diameter to thickness is increased so that compliance and the natural frequency of resonance of the cylinder is correspondingly decreased.
OBJECTS OF THE INVENTION Accordingly, the principal object of this invention is to produce an improved cylindrical transducer which will operate efliciently at lower frequencies. A more specific object of this invention is to lower the mechanical resonant frequency of a cylindrical transducer.
Other objects and features of this invention will become apparent to those skilled in the art by referring to preferred embodiments described in the following specification and shown in the accompanying drawings.
DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of one cylindrical transducer of this invention.
Patented Nov. 24, 1970 ice FIG. 3 is an end view of a cast metal cylinder of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The cylinder 10 shown in FIG. 1 is fabricated of staves 12. The staves 12 are relatively long, narrow slats of electroacoustic material and are joined edge-to-edge by adhesives or solder. If each stave is a piezoelectric ceramic, the soldered junctions 14 may contain connections 16 to the signal circuit. Preferably, the ceramic is of a barium titanate or lead zirconate titanate and preferably is polarized during manufacture by electrodes of opposed potential along opposite edges of the slats. Alternate electrodes in the cylinder are connected together and to external circuits. The external circuits may lead to either a transmitter or a receiver.
According to an important feature of this invention, the staves 12, in FIG. 1, are irregular in cross section, the irregularity comprising a radius of curvature, R which is less than the mean radius of, R the cylinder. The concaved sides of the slats can each be oriented toward the inside of the cylinder as suggested in FIGS. 1 or 3, or toward the outside of the cylinder as suggested in FIG. 2, or the concavity may alternate among these slats as shown in FIG. 4. It follows that the length of the circumferential path through the electroacoustic material is greater than in a cylinder of the same mean diameter with a smooth wall.
It can be shown that the natural mechanical resonant frequency, at which the cylinder will operate, is proportional to the stiffness or compliance of the cylinder which in turn is a function of the ratio of the diameter of the cylinder to the wall thickness of the cylinder, water loaded. That is, as the diameter, and the circumferential length of the cylinder wall are increased for a given wall thickness, the natural resonant frequency decreases. The order of magnitude of this ratio, found to be practical in sea operations, is about 30 to 1. If the diameter to wall thickness is still further increased, the end result approaches that of a paper-thin tube or wet noodle which of course is mechanically unfeasible. For most ceramics, at present in use in this art, the ratio of diameter to wall thickness should not substantially exceed 30 to 1.
Where greater ruggedness in the cylinder is required than can be provided by ceramic materials, metal may be used. Motion in the cylinder wall as a function of signal voltages may now be produced by magnetostriction. If the cylinder is of sheet nickel or other ferromagnetic metals, the signal can be inductively coupled to the cylinder, as suggested, for example, in the US. patent to Green, No. 3,177,382, issued Apr. 6, 1965. In fabricating such a transducer 22, FIG. 3, a single sheet of metal could be rolled with integral side-by-side flutes and the cylinder then closed with a single seam.
Still another technique of construction found to be satisfactory comprises casting the fluted cylinder. More specifically, metal can be vaporized in an electric arc and blown onto a form of the desired shape. As shown in FIG. 3, the metal layer 24 is sprayed on the split cylindrical form 22. The discrete metal particles of the layer 24 are quite small and densely packed, and can be laid down in layers which will have low eddy current losses, and yet can have a high coeflicient of expansion per unit of signal voltage. The voltage gradient preferably is applied by conductors wound around. the laminated coating.
What is claimed is:
1. A cylindrical transducer comprising:
a plurality of elongated slat-like staves of piezoelectric material, said staves being parallel, circularly artype-selected from the group consisting of barium ranged, and joined edge-to'edge to form a cylinder titanate, and lead zirconate titanate. having a predetermined mean radius, 3. In the cylindrical transducer defined in claim 1:
electrodes contacting each stave to functionally resaid staves comprising a sheet of magnetostrictive late signal voltages on the electrodes and physical 5 metal.
, distortion of the stave in a circumferential direc- 4. In the transducer defined in claim 1:
tion, the piezoelectric material of said staves being said cylinder comprising magnetostrictive metal cast so selected and polarized and the electrodes on each to the mentioned shape of said staves. stavebeing so .disposed that said physical distortion is principally expansion and contraction between 10 Refelfrellces Cited the side edges of said staves to cause radial displace- UNITED STATES PATENTS ment of the wall of said cylinder,
7 said staves being circular in cross-section between the gf ig 'f g'g'g joints, the radius of curvature of said cross section 2521136 9/1950 Thuras being uniform and less than said mean radius of 5 3302163 1/1967 A d the cylinder for increasing the length of the path n {ews 3 142 035 7/1964 Harris 3108.6 XR 1n the wall, circumferentially oi the cyllnder, beyond 2515446 7/1950, Gravley 310 9 6 XR the clrcumference corresponding to said predeter- 3,177,382 4/1965 Green 310 9'6 XR mined mean radius for lowering the natural me- :chanical resonant frequency of said cylinder, the 20 MILTON HIRSHFIELD Primary Examiner thickness, curvature and width of said staves being selected to stiffen the cylinder and prevent flexure in REYNOLDS: Assistant Exammel' the walls of the cylinder.
2. In the cylindrical transducer defined in claim 1:
said staves comprising piezoelectric ceramics of the a 3109.6, 26; 340-10
US771224A 1968-10-28 1968-10-28 Fluted cylinder for underwater transducer Expired - Lifetime US3543059A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US77122468A 1968-10-28 1968-10-28

Publications (1)

Publication Number Publication Date
US3543059A true US3543059A (en) 1970-11-24

Family

ID=25091113

Family Applications (1)

Application Number Title Priority Date Filing Date
US771224A Expired - Lifetime US3543059A (en) 1968-10-28 1968-10-28 Fluted cylinder for underwater transducer

Country Status (1)

Country Link
US (1) US3543059A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3816774A (en) * 1972-01-28 1974-06-11 Victor Company Of Japan Curved piezoelectric elements
US4446544A (en) * 1981-11-30 1984-05-01 The United States Of America As Represented By The Secretary Of The Navy Small diameter, low frequency multimode hydrophone
US4941202A (en) * 1982-09-13 1990-07-10 Sanders Associates, Inc. Multiple segment flextensional transducer shell
US5225731A (en) * 1991-06-13 1993-07-06 Southwest Research Institute Solid body piezoelectric bender transducer
US5900552A (en) * 1997-03-28 1999-05-04 Ohmeda Inc. Inwardly directed wave mode ultrasonic transducer, gas analyzer, and method of use and manufacture

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2515446A (en) * 1948-06-12 1950-07-18 Brush Dev Co Electromechanical transducer
US2521136A (en) * 1949-04-28 1950-09-05 Commerce National Bank Of Hydrophone
US3043967A (en) * 1960-01-13 1962-07-10 Walter L Clearwaters Electrostrictive transducer
US3142035A (en) * 1960-02-04 1964-07-21 Harris Transducer Corp Ring-shaped transducer
US3177382A (en) * 1961-01-25 1965-04-06 Charles E Green Mosaic construction for electroacoustical cylindrical transducers
US3302163A (en) * 1965-08-31 1967-01-31 Jr Daniel E Andrews Broad band acoustic transducer
US3311352A (en) * 1965-03-25 1967-03-28 Bulova Watch Co Inc Magnetostrictive transducers

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2515446A (en) * 1948-06-12 1950-07-18 Brush Dev Co Electromechanical transducer
US2521136A (en) * 1949-04-28 1950-09-05 Commerce National Bank Of Hydrophone
US3043967A (en) * 1960-01-13 1962-07-10 Walter L Clearwaters Electrostrictive transducer
US3142035A (en) * 1960-02-04 1964-07-21 Harris Transducer Corp Ring-shaped transducer
US3177382A (en) * 1961-01-25 1965-04-06 Charles E Green Mosaic construction for electroacoustical cylindrical transducers
US3311352A (en) * 1965-03-25 1967-03-28 Bulova Watch Co Inc Magnetostrictive transducers
US3302163A (en) * 1965-08-31 1967-01-31 Jr Daniel E Andrews Broad band acoustic transducer

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3816774A (en) * 1972-01-28 1974-06-11 Victor Company Of Japan Curved piezoelectric elements
US4446544A (en) * 1981-11-30 1984-05-01 The United States Of America As Represented By The Secretary Of The Navy Small diameter, low frequency multimode hydrophone
US4941202A (en) * 1982-09-13 1990-07-10 Sanders Associates, Inc. Multiple segment flextensional transducer shell
US5225731A (en) * 1991-06-13 1993-07-06 Southwest Research Institute Solid body piezoelectric bender transducer
US5900552A (en) * 1997-03-28 1999-05-04 Ohmeda Inc. Inwardly directed wave mode ultrasonic transducer, gas analyzer, and method of use and manufacture

Similar Documents

Publication Publication Date Title
US2830274A (en) Electromechanical transducer
US3142035A (en) Ring-shaped transducer
US2558563A (en) Piezoelectric strain gauge
US6346764B1 (en) Multilayer piezoelectric transformer
US6366006B1 (en) Composite piezoelectric transformer
US3177382A (en) Mosaic construction for electroacoustical cylindrical transducers
US2900536A (en) Design of electro-mechanical transducer elements
US3230504A (en) Open hemispherical transducers
US3845333A (en) Alternate lead/ceramic stave free-flooded cylindrical transducer
US2636135A (en) Stress-coupled core and crystal transformer
US3115588A (en) Electroacoustical apparatus
US3202962A (en) Transducer
US2947886A (en) Piezoelectric ultrasonic transducer
US2895061A (en) Piezoelectric sandwich transducer
US2732536A (en) miller
US6040654A (en) Piezoelectric transformer
US3982144A (en) Directional low-frequency ring hydrophone
US2550771A (en) Magnetostriction transducer
US6215227B1 (en) Thickness mode piezoelectric transformer with end-masses
US3543059A (en) Fluted cylinder for underwater transducer
US4065687A (en) Supersonic vibrator with means for detecting vibrating speed
US3284762A (en) Mechanical-to-electrical transducer
US5220538A (en) Electro-acoustic transducer insulation structure
US2427062A (en) Vibrational energy transmitter or receiver
US3209176A (en) Piezoelectric vibration transducer