Sarvajanik college of Engineering

Assignment for Ultrasonic

Name

Lumbhani Kishan J.

Branch

Roll No

File name & id

Subject

Guided By

Computer Engineering

14

CO0914

Assignment for Ultrasonic

Niket shastri & Isha Desai

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:::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

**Introduction**

The word ultrasonic combines the Latin roots ultra, meaning "beyond," and sonic, or sound.. These sounds have applications for imaging, detection, and navigation—from helping prospective parents get a glimpse of their unborn child to guiding submarines through the oceans.

-:Review:-

---Ultrasonic refers to any study or application of sound waves that are higher frequency than the human audible range. The field of ultrasonic thus involves the use of sound waves 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 25 MHz.

---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 material in an adverse manner.

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.

Ferromagnetic rod

N S

P

GC

L2 L1

C1+

-

L.T.

mA

XxA B

Ultrasonic waves

P- PlateC-CathodeG-GridF-FilamentL.T.-Low tension BatteryH.T.-High tension Battery

F

Ultrasonic waves

Working:-

when the battery is switched on, the tank circuit L1C1 in the plate circuit of the triode sets up an alternating current of frequency,

f = 1

2 √ L1C1

As a result rod gets magnetized by the plate current. any change in current brings change in the magnetization A change in the length of rod. this is gives flux in coil L2,thereby inducing an emf in the coil L2. this emf is applied to the triode valve and is fed back to coil L2, so there will be oscillations

These is varied by capacitor C1, the frequency of oscillation of the tank circuit gets varies. If the tank frequency matches with the frequency of natural frequency of the material then because of resonance the rod vibrates with producing ultrasonic waves at the end of the rod. The miliammeter gives maximum value of the resonance.

The frequency of ultrasonic produced by this method depends upon the length l density ..and the elastic constant E of the rod.

i.e., f = 1 E

2l √

Advantages:-

1.The deign of this generator is very simple & cost is law

2.At low frequencies, large o/p is possible without the risk of damage to the oscillatory circuit.

3.Frequencies ranging from 100Hz to 3000kHz.

Disadvantages:-

1.It can’t generate frequencies of ultrasonic greater than 3000kHz

2.The frequency of oscillation depends greatly on temperature.

3.There will be losses of energy due to hysteresis and eddy current.

2 Describe minimum 20 applications of Ultrasonic waves in different fields.

Science and engineering

1. 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 without using any fluxes.

4. It is used to weld some metals which can’t be welded by electric or gas welding

5. 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 water and mercury which finds application in the preparation of photographic films, face creams etc.

7.It act Like a catalytic agent and accelerate chemical reactions.

Medicine

8. 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 of foetus 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 won't 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.

14.Laser Ultrasonic Camera

Measurement of the characteristics of ultrasonic wave motion, such as wave speed, attenuation and the presence of scattered waves from microstructural features or flaws are used to perform NDE for quality control. Laser ultrasonics refers to the process whereby lasers are used 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 generation through the process of thermoelastic expansion or weak ablation. The method of detection involves interferometry of the Michelson, Fabry-Perot, and Photorefractive (adaptive) types. Commercially available systems utilize these interferometric methods and provide a "point and shoot" single point measurement capability. In order to perform measurements over a large surface, the laser generation and detection spots must be scanned in a raster fashion over the area recording ultrasonic signals at each location.

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.

15.Ultrasonic Flow meters in Waste Water Plants

Introduction:-

Waste Water Treatment Plants require a large variety of instrumentation in order to

monitor and control the processes in the different stages. For the purpose of flow

metering; do electromagnetic flow meters and ultrasonic flow meters offer the features and

performance which is demanded in these applications.

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

Chemical reaction

Other

Ultrasonic can also speed up certain chemical reactions. Hence, it has gained application in agriculture, thanks to research which revealed that seeds subjected to ultrasound may germinate more rapidly and produce higher yields. In addition to its uses in the dairy industry, noted above, ultrasonics is of value to farmers in the related beef industry, who use it to measure cows' fat layers before taking them to market

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.

3 Describe the construction and method of measuring the wavelength and velocity of ultrasound in liquid medium.

Collimator

Sodium Lamp

Oscillator

d

Reflector

Telescope 1st order maximum

1st order maximum

Central maxima

Screen

A B

Q

Liquid column

The arrangement of experiment is shown in figure

Construction:-

The arrangement of experiment is shown in figure. There is a glass vessel containing 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 the bottom 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 ultrasonic produce. thus the liquid behave like grating. This grating is put on the prism table of a spectrometer and a parallel beam of light from the monochromatic source S is passed through the liquid angles to the wave. Since, the liquid is behaving like a grating the light beam on passing through it gets diffracted and produces a diffraction pattern. The pattern is viewed through the telescope.

The diffraction pattern consists of central maxima with other maxima on both sides like 1st order maxima etc. If is the angle of diffraction for the nth order principle maxima then,

d sin = nג where ג = wavelength of light which is used

d = grating element distance between adjacent nodal planes.

d = גu

2 where u = wavelength of ultrasonic

therefore, ג u sin = n ג or u = 2n ג

2 sin

When we know ג and n and by measuring , we can know the wavelength of ultrasonic.

If the resonant frequency of the ultrasonic generator is f; then the velocity of ultrasonic waves through liquids and gases at various temperatures can be determined………

4 How is the depth of sea measured using Ultrasonic waves?

Ship

Receiving TransducerTransmitting Transducer

A BO

C

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 based on 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 get reflected 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 sea and to get reflected from 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 sea and to get reflected to the top surface is noted using a CRO. If the velocity of the ultrasonic wave is already known; then,

Velocity v = Distance traveled

Time taken

v = AC+CB 2CO

t t

Therefore,

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 determine the depth of the sea.

Q

----------

++++++A

B

L2

L1C1L.T.

H.T.

+

-Triode

A

GC

Ultrasonic

Ultrasonic

Secondary

L3

Primary

Piezoelectric oscillator method

Over view of piezoelectric method

5 Explain in detail Piezo-electric effect and Piezo-electric crystals.

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Optic axis

Pressure

PressureX1 X2 X3 Electric axis

Y1 Y2 Y3 Mechanical axis

X1 X1

X2

X2

X3

X3

Y1

Y1

Y2

Y2

Y3

Y3

When pressure is applied to one pair of opposite faces of crystals like quartz, tourmaline, Rochelle salt etc. cut with their faces perpendicular to its optic axis , equal and opposite charges appear across its other faces as shown in figure . This phenomena is known as piezoelectric effect. The frequency of the developed emf is equal to the frequency of dynamical pressure.

The sign of the charges gets reversed if the crystal is subjected to tension instead of pressure.

The electricity produced by means of piezoelectric effect is called piezoelectricity. The matter which can undergo piezoelectric effect are called as piezoelectric materials or crystals.

Piezo-electric effect

Lumbhani Kishan J.

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