US3058015A - Dissipation of high frequency vibratory energy - Google Patents

Description

SEECH Y?" Oct. 9, 1962 F. NEsH 3,058,015

DIssIPATIoN 0F HIGH FREQUENCY VIBRATORY ENERGY Filed May 5, 1960 Tlcl.. L #layer a/(me/l/ ATTORNEYS United States Patent C) 3,058,015 DISSIPATION F HIGH FREQUENCY VIBRATQRY ENERGY Florence Nesh, 164 Hart St., Brooklyn 6, N.Y. Filed May 3, 1960, Ser. No. 26,658 4 Claims. (Cl. S10-8.7) (Granted under Title 35, U.S. Code (1952), sec. 266) 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.

This invention relates to the dissipation of vibratory energy and t-he transducer therefor, and particularly for use with and in vehicles such as missiles and other space vehicles.

In the journal Missiles `and Rockets for September 14, 1958, on page 7, `there occurs a statement that scientists have found that silent, high frequency sounds given olf by large rocket space vehicle boosters may injure the health of launching crews, that since sounds have been found to cause stomach ulcers and reproductive disorders in animals, efforts were being made to avoid this danger to the health of Ithe launching crews by the use of effective mufflers for the big rockets.

An object of this invention is to provide a simple, practical and relatively inexpensive broad band transducer for effectively dissipating the vibratory energy normally given off by the space vehicles and their boosters, in a manner that will avoid any danger to the health of the launching crews, which will not materially interfere with the usual handling and launching of such vehicles, and which may be employed to reduce the effect of high frequency vibrations in other objects where such vibrations are troublesome.

Other objects and advantages will be apparent from the following description of one example of the invention, Iand the novel `features will be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawing:

FIG. l is a perspective view of an element o-f electrostrictive material that may be used in connection with this invention; and

FIG. 2 is an elevation, in section, on a larger scale, with a schematic circuit, illustrating one example of the invention. v

In the illustrated embodiment of the invention, yan electrostrictive or piezoelectric transducer 1 is attached, in any suitable manner, to `a wall 2 of a space vehicle or its booster, so that vibrations of the wall acting on the transducer will be converted in the transducer into electric energy in the form of electric currents. These created electric currents are passed through a utilization circuit 3 Where the electric energy is dissipated. The transducer 1 is formed of a body 4 of any suitable electrostrictve or piezoelectric material such as, for example, of quartz crystals, Rochelle salt crystals, ammonium dihydrogen phosphate crystals, and certain ceramic materials such las barium titanate, lead titanatelead zirconate, barium titanate with a small amo-unt of lead titanate or calcium titanate, and tourmaline. Any electrostrictive material may :be used. This body 4 is preferably of wedge shape with opposite, diverging faces 5 and 6 that carry electroded layers or coatings 7 and These coatings may be provided in any suitable manner, one of which is by condensing vaporized metals such as gold or silver upon the divergent faces of the body, or by painting the divergent faces of the body with a silver paint and baking it. The electroded layers are usually applied after the body has been fired. Other methods of providing the electrode surfaces are by evap- Mice orating, electroplating, or electrodepositing the metal on the opposite divergent faces. Barium titanate is gaining wide use as an electrostrictive material, because i-t manifests large electrostrictive effects when its molecular electric dipoles are oriented by means of a polarizing voltage, and because it has a high dielectric constant and relatively low impedance, resistance to moisture, ruggedness, ability to operate over wide temperature ranges, is of low relative cost per unit surface area, and can be easily produced in `a great variety of sizes and shapes. The body 4 with its electroded layers or surfaces is polarized in a direction between the layers.

One of the divergent, electroded faces, such as 6, of the body 4 is caused to abut, face to face and flat against a metal plate 9, such as of brass or copper, for example, which is secured in any suitable manner to the wall 2 of the vehicle or its booster that vibrates. The platel 9 may be secured to wall 2 by screws 10, and preferably also by a layer 11 of adhesive or cement interposed between the pla-te 9 and wall 2. The cement layer 11 provides a very secure contact between the abutting surfaces of plate 9 and wall 2. If there are air bubbles or air layers between the plates 9 and wall 2, it interferes with the response of the transducer to the vibrations in wall 2, and the cement eliminates the possibility of having such interposed air bubbles or air layers between plate 9 and wall 2.

Another metal plate 12 such as of brass or copper, for example, is disposed face to face and fiat against the electroded surface or layer 7 of the other divergent face 5 of body 4, and bodies 13 and 14 of a suitable insulating cement are disposed at the larger 4and smaller ends of the -body y4 and connect :the plates 9 and 12. These cement bodies unite the plates 9 and 12 against separation and in confining rel-ation to the electrostrictive body 4, so that the plates 9 and 12 and body 4 with its electroded layers 7 and 8 form a unit acting as the transducer 1. Any suitable insulating cement may be used for the cement bodies 13 and 14 but the well-known epoxy and arylic types of cements are useful for the cement bodies 13 and 14 and for the cement layer 11.

Circuit wires 15 4and 16 are electrically connected to plates 9 and 12., respectively. Wire 15 includes in series therein a control switch 17 and a variable resistor 18, and one or more instruments or electrical devices 19, 2t) and 21 may be connected in parallel or series with wires 15 and 16 to complete the utilization circuit 3. The utilization circuit is carried by one of the plates 9 and 19 or by the wall 2. When the missile or vehicle, or its booster, having wall 2 is launched, the wall 2 will vibrate at a very high frequency or emit ultrasounds, and such vibrations will be |applied to the transducer 1 carried thereby. The vibrations applied to the transducer will create electric currents in the transducer, and such currents will vbe passed through the utilization circuit where the energy of such currents will be used up to advantage or dissipated. The devices 19, 20 and 21 may be instruments or devices used in connection with the flight of the missile `or vehicle and receive their operating current from the transducer, or the devices 19, 20 and 21 may be `any devices to receive the currents from the transducer and dissipate the electric energy.

The transducer body 4 may have opposite parallel, electroded faces, but since the ultrasound or high frequency vibrations produced by the missile or vehicle or its booster may cover a broad spectrum or band of frequencies, the wedge-shaped body 4 `appears to be preferable, and responsive to the broadest possible band of frequencies of the vibrations, since each area of a different thickness of body 4 will respond best to a particular part of the frequency band, and together can be highly responsiveto a broad frequency band.L The particular electrostrictive material selected for the body 4 will depend upon the temperature and other conditions of expected use.

Barium titanate of uniform thickness responds to vibration frequencies of more than one fundamental frequency, but when in wedge shape its band of frequencies is excellent. y

Uutrasounds and very high frequency vibrations do not propagater in the same way as audible sounds and vibrations, and do not go out in all directions as a circular wave. There are few absorbente for ultrasounds and vibrations in the same nature las for audible sounds. Most solids and liquids are good ktransmission media for ultrasounds and vibrations, Air and vacuum` are the best dampers for ultrasounds, but their use presents a,

. of the transducer, the mechanical forces so applied cause the production of a current in the transducer ofthe same frequency as the vibrations, if both are of one fundamentaly frequency. While all of this vibration may not be converted into an electric current, none will leave the system ,as ultrasound, and some will be reflected back and forth between the transducer body and the plate faces 9 and 12, and so belost in attenuation in the ma* terial of the body 4. -There will be some loss at each f interface of bonding materials and some conversion to heat.

damping of ultrasounds and high frequency vibrations in missiles and their boosters, the basic principles so employed may be applied broadly to the damping of other response to a broad While this invention is primarily applicable to the electrically insulating means securing said metal plates j in abutting relation to said opposite, divergent, electrod- 2. A transducer device which comprises an electroi. strictive body of wedge shape with its broadest faces in cement isan epoxy cement.

ultrasounds and very high frequency vibrations, where other or usual methods of damping are inadequate.

It will be understood that various changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within thep'rinciple andscope ofk the invention, as expressed in the appended claims.

kI claim:

l. A transducer device sensitive to a wide band of vibrations for dissipating vibrations over a broad frequency band of a vehicle to which it may be attached,

opposite divergent relationship and having said kfaces electroded, a rigid metal plate disposed ilat against each electroded face ofwsaid body and extending beyondfthe periphery of said body forming an overlapping area, electrically insulating cement disposed between said metal plates lling the volume between saidoverlapping to which said body is subjected and dissipating its energy,

wherebywhcn one of said plates is attached to an object subject to vibration, much energy of said vibration over a broad frequency bandinfthe object will ber converted by said body into electric 'energy and the latter dissipatek ed in said utilization circuit.

3. `The transducer according to claim 2, wherein said 4.fThe transducer according to elaim`2, cement is arylic cement.

References Cited in the tile of this patentr j j UNITED STATES PATENTS f L2,261,791 i Bokovoy Nov. 4, 2,361,071 f Vang f ....i -..p Oct.,24, 2,534,0065 De Lanoy etal. Dec. l2, 1950 2,661,622 y Severs Dec. 8, 1953 2,716,708 Bradfield Aug. 30, 1955 i 2,716,893 Birdsall Sept. 6, 1955 2,882,989 Bruel et al. Apr. 21, 1959 2,924,814 Simpson s Feb. 9, 1960 2,959,242 Mulller et al. Nov.-8, 1960 y.FOREIGNr PATENTS j y 473,636f Great Britain Oct., 18, 1937v 931,689 Germany Q.. Aug. 16, 1955 OTHER REFERENCES Technical Paper on the Measurement of In-Flight Vibration Under 4Environmental Extremes, by Warren kD. Hancock, given at the 5th Annual I.S.A. Flight, In-

strumentation Symposium, ton, 6 pages.

May 1959, Seattle, Washingwhereiny said

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