ultrasonics

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  • !  √  ∆∂  גגגּ
  •  √  ∆∂  גגגּ
  • ultrasonics

    1. 1. Sarvajanik college of Engineering Assignment for Ultrasonic Name :-- Lumbhani Kishan J. Roll No :-- 14 Branch :-- Computer EngineeringFile name & id :-- CO0914 Subject :-- Assignment for Ultrasonic Guided By Niket :-- shastri & Isha Desai
    2. 2. :::Questions:::1)) Explain the theory of production of ultrasonic waves using Magnetostriction Effect.2)) Describe minimum 20 applications of Ultrasonic waves in different fields.3)) Describe the construction and method of measuring the wavelength and velocity of ultrasound in liquid medium.4)) How is the depth of sea measured using Ultrasonic waves?5 )) Explain in detail Piezo-electric effect and piezo-electric crystal
    3. 3. **Introduction** The word ultrasonic combines the Latin roots ultra, meaning "beyond," andsonic, or sound.. These sounds have applications for imaging, detection, and navigation—from helping prospective parents get a glimpse of their unborn child to guidingsubmarines through the oceans. -:Review:----Ultrasonic refers to any study or application of sound waves that are higher frequencythan the human audible range. The field of ultrasonic thus involves the use of soundwaves outside the audible range for humans---Music and common sounds that we consider pleasant are typically 12 kHz or less,while some humans can hear frequencies up to 20 kHz.---Ultrasonic waves consist of frequencies greater than 20 kHz and exist in excess of 25MHz.---Ultrasonic waves are used in many applications including plastic welding, medicine,jewelry cleaning, and nondestructive test.Within nondestructive test, ultrasonic waves give us the ability to “see through”solid/opaque material and detect surface or internal flaws without affecting the materialin an adverse manner.
    4. 4. 1. Explain the theory of production of ultrasonic waves using Magnetostriction Effect.Principle:- When a ferromagnetic material in the form of a rod is subjected to an alternating magnetic field as shown in figure, the rod undergoes alternate contractions and expansions at a frequency equal to the frequency of the applied magnetic field –This phenomena is known as Magnetostriction effect.Construction:- The circuit diagram is shown in figure. The ferromagnetic rod AB is clamped a the middle X. The coils L1 and L2 are wound at the ends of the rod. To the coil L1 a variable capacitor connected in parallel and this combination make tank Or resonant circuit. One side of this tank circuit is connected to the anode of triode through ammeter. Other side is connected to the cathode through a H.T. battery. L2 is connected Betn the grid and the cathode.
    5. 5. Ferromagnetic rod N S L2 L1 A x B XUltrasonic waves Ultrasonic waves mA P- Plate C-Cathode G-Grid C1 + F-Filament L.T.-Low tension P Battery H.T.-High tension G - Battery C F L.T.
    6. 6. Working:- when the battery is switched on, the tank circuit L1C1 in the plate circuitof the triode sets up an alternating current of frequency, f = 1 2 √ L1C1 As a result rod gets magnetized by the plate current. anychange in current brings change in the magnetization A change in thelength of rod. this is gives flux in coil L2,thereby inducing an emf in the coilL2. this emf is applied to the triode valve and is fed back to coil L 2, so therewill be oscillations These is varied by capacitor C1, the frequency of oscillation ofthe tank circuit gets varies. If the tank frequency matches with thefrequency of natural frequency of the material then because of resonancethe rod vibrates with producing ultrasonic waves at the end of the rod. Themiliammeter gives maximum value of the resonance. The frequency of ultrasonic produced by this method dependsupon the length l density ..and the elastic constant E of the rod. i.e., f = 1 E 2l √ 
    7. 7. Advantages:-1.The deign of this generator is very simple & cost is law2.At low frequencies, large o/p is possible without the risk of damage to the oscillatorycircuit.3.Frequencies ranging from 100Hz to 3000kHz.Disadvantages:-1.It can’t generate frequencies of ultrasonic greater than 3000kHz2.The frequency of oscillation depends greatly on temperature.3.There will be losses of energy due to hysteresis and eddy current.
    8. 8. 2 Describe minimum 20 applications of Ultrasonic waves in different fields.Science and engineering1. It is used to detect flaws or cracked in metals.2.It is used to detect ships, submarines, iceberg etc, in ocean.3. It is used for soldering aluminium coil capacitors, aluminium wires and plates withoutusing any fluxes.4. It is used to weld some metals which can’t be welded by electric or gas welding5. It is used to cutting and drilling holes in metals.6. It is used to form stable emulsion of even immiscible liquids like water and oil or waterand mercury which finds application in the preparation of photographic films, face creamsetc.7.It act Like a catalytic agent and accelerate chemical reactions.
    9. 9. Medicine8. It is used to remove kidney stones and brain tumours without shedding any blood.9. It is used to remove broken teeth.10. It is used for sterilising milk and to kill bacteria.11. It is used to study the blood flow velocities in blood vessels of our body.12. It is used as a diagnostic tool to detect tumours, breast cancer and also the growth offoetus can be studied.Another Uses:- 13 .A Cheap Ultrasonic Range Finder Working- Everybody knows the speed of the sound in the dry air is around 340 m/s. Send a short ultrasonic pulse at 40 kHz in the air, and try to listen to the echo. Of course you wont hear anything, but with an ultrasonic sensor the back pulse can be detected. If you know the time of the forth & back travel of the ultrasonic wave, you know the distance, divide the distance by two and you know the range from the ultrasonic sensor to the first obstacle in front of it.
    10. 10. 14.Laser Ultrasonic Camera The INL Laser Ultrasonic Camera directly images (without the need for scanning) the surface distribution of subnanometer ultrasonic motion at frequencies from Hz to GHz. Ultrasonic waves form a useful nondestructive evaluation (NDE) probe for determining physical and mechanical properties of materials and parts. The reason for this is that ultrasonic waves or "sound" can be generated in all forms of matter: liquids, solids and gases and exhibit information about the material in which they travel. Measurement of the characteristics of ultrasonic wavemotion, such as wave speed, attenuation and the presence of scatteredwaves from microstructural features or flaws are used to perform NDE forquality control. Laser ultrasonics refers to the process whereby lasers areused for both generation and detection of ultrasonic waves in materials,thereby providing a noncontacting method for performing ultrasonic NDE.The current state of the art utilizes a pulsed laser for ultrasonic generationthrough the process of thermoelastic expansion or weak ablation. Themethod of detection involves interferometry of the Michelson, Fabry-Perot,and Photorefractive (adaptive) types. Commercially available systems utilizethese interferometric methods and provide a "point and shoot" single pointmeasurement capability. In order to perform measurements over a largesurface, the laser generation and detection spots must be scanned in araster fashion over the area recording ultrasonic signals at each location.
    11. 11. 15.Ultrasonic Flow meters in Waste Water PlantsIntroduction:- Waste Water Treatment Plants require alarge variety of instrumentation in order tomonitor and control the processes in the differentstages. For the purpose of flowmetering; do electromagnetic flow meters andultrasonic flow meters offer the features andperformance which is demanded in theseapplications. The constituent parts of an ultrasonic flow meter are a hydrostatic pressure sensor for measuring depth, a temperature sensor, and an ultrasonic transmitter/receiver pair for measuring water velocity. These are all controlled by a data logger, which records data as specified from the scheme created by the user software. A single cable links the submerged instrument to a weather-proof polycarbonate enclosure which provides a data download point, and where the battery is stored. The enclosure has an optional LCD display. The flow meter is mounted on (or near) the bottom of the stream/pipe/culvert and measures velocity and depth of the water flowing over it. Normally it is faced upstream and reports positive flow but it is a bi-directional instrument capable of measuring
    12. 12. Chemical reaction Ultrasonic can also speed up certain chemical reactions. Hence,it has gained application in agriculture, thanks to research which revealedthat seeds subjected to ultrasound may germinate more rapidly andproduce higher yields. In addition to its uses in the dairy industry, notedabove, ultrasonics is of value to farmers in the related beef industry, whouse it to measure cows fat layers before taking them to marketOther Ultrasonic soldering implements the principle of cavitations, producing microscopic bubbles in molten solder, a process that removes metal oxides. Hence, this is a case of both "binding" (soldering) and "loosening"—removing impurities from the area to be soldered. The dairy industry, too, uses ultrasonics for both purposes: ultrasonic waves break up fat globules in milk, so that the fat can be mixed together with the milk in the well-known process of homogenization. Similarly, ultrasonic pasteurization facilitates the separation of the milk from harmful bacteria and other microorganisms.
    13. 13. 3 Describe the construction and method of measuring the wavelength and velocity of ultrasound in liquid medium. The arrangement of experiment is shown in figure Reflector Liquid column Telescope 1st order maximum Central maxima d 1st order maximum Collimator ScreenSodium Lamp A B Q Oscillator
    14. 14. Construction:- The arrangement of experiment is shown in figure. There is a glass vesselcontaining the liquid with a reflector R fixed within the vessel at its top. A quartz crystal Q placed between two metal plates A and B is mounted at thebottom of the plate vessel. The metallic plates are connected to an oscillator whose frequency is adjusted that,the crystal vibrates in resonance with the frequency of the oscillator and thus the ultrasonicproduce. thus the liquid behave like grating. This grating is put on the prism table of aspectrometer and a parallel beam of light from the monochromatic source S is passed throughthe liquid angles to the wave. Since, the liquid is behaving like a grating the light beam onpassing through it gets diffracted and produces a diffraction pattern. The pattern is viewedthrough the telescope. The diffraction pattern consists of central maxima with other maxima on both sideslike 1 order maxima etc. If  is the angle of diffraction for the nth order principle maxima then, st d sin = n‫ג‬ where ‫ = ג‬wavelength of light which is used d = grating element distance between adjacent nodal planes. d = ‫ג‬ u 2 where  u = wavelength of ultrasonic therefore, ‫ ג‬u sin = n ‫ ג‬or u = 2n ‫ג‬ 2 sin 
    15. 15. When we know ‫ ג‬and n and by measuring  , we can know the wavelength ofultrasonic. If the resonant frequency of the ultrasonic generator is f; then the velocity ofultrasonic waves through liquids and gases at various temperatures can be determined………
    16. 16. 4 How is the depth of sea measured using Ultrasonic waves? A Ship O B Transmitting Transducer Receiving Transducer C
    17. 17. Sonar is a device which stands for Sound Navigation and Ranging. By using SONAR, the distance and direction of submarines, depth of sea,depth of rocks in the sea , the shoal of fish in sea etc can be determined. also ultrasonic waves can be used to find the depth of the sea. It is basedon the principle of echo sounding. The figure shows the use of ultrasonic to find the depth of the sea The ultrasonic waves sent from the point A travel through sea water and getreflected from the bottom of the sea. The reflected waves are received at the point B. The time t taken for the ultrasonic wave to travel to the bottom of the seaand to get reflected from bottom of the sea. The reflected waves are received at thepoint B. The time t taken for the ultrasonic wave to travel to the bottom of the seaand to get reflected to the top surface is noted using a CRO. If the velocity of theultrasonic wave is already known; then, Velocity v = Distance traveled Time taken v = AC+CB 2CO t tTherefore, CO = Depth of the sea = v t 2 Thus ,the depth of the sea can be calculated using the formula Fathometer or Echo meter is a device which is directly calibrated to
    18. 18. Over view of piezoelectric method P r Secondary i m L2 a r H.T. y A+ Ultrasonic ++++++ Q A - Triode G C ---------- Ultrasonic B C1 L1 L.T. L3 Piezoelectric oscillator method
    19. 19. 5 Explain in detail Piezo-electric effect and Piezo- electric crystals. Pressure X3 Y2 X2 + Y3 Y1- Optic axis- +- + X1 X1- +- + Y1 Y3 X2 Y2 X3 Pressure X1 X2 X3 Electric axis Y1 Y2 Y3 Mechanical axis
    20. 20. Piezo-electric effect When pressure is applied to one pair of opposite faces ofcrystals like quartz, tourmaline, Rochelle salt etc. cut with theirfaces perpendicular to its optic axis , equal and opposite chargesappear across its other faces as shown in figure . Thisphenomena is known as piezoelectric effect. The frequency of thedeveloped emf is equal to the frequency of dynamical pressure. The sign of the charges gets reversed if the crystal issubjected to tension instead of pressure. The electricity produced by means of piezoelectric effect iscalled piezoelectricity. The matter which can undergopiezoelectric effect are called as piezoelectric materials orcrystals.
    21. 21. Presentation by:-Lumbhani Kishan J.

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