Ultrasonic testing non destructive testing ppt

1. Introduction to Ultrasound
1- Sounds energy was discovered before the
discovery of X-rays.
2-Curie brothers (Jacques and Pierre) ,first
discovered piezoelectric effect that produces
ultrasound in 1880.
3- First they discovered the production of an
electrical pulse from the application of the
mechanical pressure on certain crystals.
4- The reversed piezoelectric was discovered a
year later.

2. Industrial applications
1-The first practical uses of ultrasound failed to
locate the Titanic which sank in 1916.
2- Ultrasonics improved during the Second World
War with military development of SONAR for
detection of submarines.
3- USA and England developed pulse echo
ultrasound equipment for flow detection in
metals.

3. Detection of submarines by ultrasound

4. Profile of the sea bed by echo sounder

5. Medical applications
1- The first ultrasound unit was designed by Dussik in
Austria in 1937.
2- He used two transducers on opposite sides of the head
in an attempt to visualize the cerebral ventricles.
3- In 1949 a quartz transducer was made .
4- The picture of the underline anatomy was displayed as
dots on the oscilloscope screen.
5- The initial sonograms were made with transducer and
objects submerged in water .
6- In 1960s ,the water tank was replaced by a mineral oil as
a coupling agent.

6. What is sound?
Sound is a type of wave.
What is a wave?
Wave is a variation that transfers energy progressively from
point to point in a medium.

7. How do sound waves move from one point to another?
Sound waves require matter to exist, travel
or propagate from one point to another.
All matters are composed of molecules.
Sound waves moves through the cyclic vibrations of
molecules in the matter.
vibrations The sound waves of the musical instruments
reach our ears through of air molecules.
Sound waves produce a force (pressure) on the
molecules of a medium displacing them towards and
away from the source in a cyclic fashion.

8. Fundamental of waves
The wave is the co-ordinated disturbance moving at a fixed
speed .
Types:
1-Electromagnetic waves:
--Radiation( X.ray,gamma rays,)
--light (visible light, ultraviolet, and infrared light).
--Microwaves.
--Radio waves.
2-Mechanical waves:
--Ocean waves.
--Seismic waves.
--Sound waves.

9. Electromagnetic vs mechanical waves
EMW
1-The velocity is equal to
the speed of light
2-Because it is a
transverse wave ,no
medium required.
3-The frequency ranges
from 100Hz(radio w) to
10 24Hz (gamma rays).
4-Produced by electrical
charge.
MW
1- The velocity depends
on medium
2-Because it is a
longitudinal wave a
medium is required.
3-The frequency ranges
from 20Hz—1MHz.
4- The source must be a
vibrating source

10. Wave direction
1- longitudinal waves :.
The direction of travel of the wave is in the same
direction as particle motion. e.g. sound wave.
2- Transverse waves :
The motion of the particles is perpendicular to the
direction of propagation of the wave energy. e.g. wave
motion resulting from a stone thrown in the water.

11. Transverse versus Longitudinal waves

12. Stone is thrown into a still pond

13. Compression and rarefaction of air
molecules

14. Mechanical waves sound waves)
Definition:
It is the propagation of energy through a medium by cyclic pressure
vibration.
It requires a deformable medium for propagations
Wave equation:
A(t)=A*sin(ft)
where A = amplitude at time t.
A*= peak amplitude.
f = frequency

15. Wave Power and Intensity
Power is the rate at which work is performed.
The unit of power is watts.
Intensity is the amount of energy per second
(power) that passes through a specified
area.
The unit of intensity is w/m2.
Amplitude:
It means a maximum cyclical change in a quantity,
such as the pressure in an ultrasound wave. It is
the difference between the maximum value and
equilibrium of the acoustic variable.

16. The Decibel
Definition
The decibel is a unit which used to compare the
relative intensities of two ultrasound beams and
expressed in logarithms to base 10.
Equation
Relative intensity level (dB)
dB=10log I/I0
Where : I =Intensity of a beam at any point.
I0 =initial intensity of a beam
Relative signal level (dB)
dB=20 log A2/A1

17. Amplitude and Intensity
Amplitude is the quantitative statement regarding the
magnitude or strength of a wave.
A wave of a higher amplitude is accompanied by a greater
pressure amplitude.
In case of calculating the biological effects , the intensity is
measured as a ratio of pressure amplitude and acoustic
impedance of a medium.

18. Mechanical wave properties
Wavelength:
Definition:
It is the distance between two adjacent bands of compression and
rarefactions.
Units:
Meter

19. The wave velocity
Definition:
Velocity is the speed at which the wave moves through the
medium . It is often called the speed of propagation.
Units:
Meter per second.
All acoustic waves are transmitted through the same medium
at the same velocity even though their frequencies are
different.

20. Velocity of sound in some non-biological material
Material Velocity (m/s)
Air 330
Water 1480
Lead 2400
Aluminum 6400

21. Velocity of sound in selected tissues
Materials Velocity (m/s)
Lung 600
Fat 1460
Aqueous hummer 1510
Liver 1555
Blood 1560
Kidney 1565
Muscle 1600
Lens of eye 1620
Skull bone 4030

22. The wave Frequency
Definition:
Frequency is the number of cycles that pass a given point
per one second.
Units:
Hurtz (Hz)
One hurtz=One cycle per second

23. Nature of sound
Familiar definition :
Sound is the sensation perceived by the sense of hearing
Fundamental definition:
Sound is mechanical energy transmitted by pressure waves in
a material medium.
Characteristics of sound :
1-It is a form of energy.
2-It is a mechanical energy.
3-It needs a material for transference.
4-It propagates through a material medium.

24. Sources of sound
Sound production require a vibrating objects.
Sources include:
1- musical instruments.
2-Human vocal cords.
3-Peizoelectric transducer
4-Certain animal like a bat.

25. The sound waves need a media to propagate through it

26. Bats uses ultrasound to detect flying
insects

27. Acoustic variables
Acoustic variables are quantities which vary in
rhythmic , cyclic fashion in time and in space.
Acoustic variables include:
1-Pressure.
2-Density.
3-particle motion.
4-Temprature.

28. Pressure:
Is the concentration of force ,or, Force over a given
area. Unit of pressure is pound per square inch.
Density:
Is the concentration of mass or weight. Unit of
density is pound per cubic feet and kilogram per
cubic meter.
Temperature:
Is the concentration of heat energy. Unit of temperature
Is a degree of (Fahrenheit, Celsius, or Kelvin scale).
Particle motion includes the displacement, speed,
velocity, and acceleration of a particle.

29. Piezoelectric, Piezoelectric effect
The prefix Piezo means pressure
It describes the formation of electrical
charge on the surfaces of the crystal when
pressure (mechanical stress) is applied.

30. The reverse Piezoelectric effect
It is the production of ultrasound
(mechanical energy) when an electrical signal is applied to
the crystal.
The crystal undergoes mechanical deformation ,
contracting or expanding depending on the polarity of the
electric signal.

31. Production of sound waves
Ultrasound waves are produced when
an electrical signal is applied to a
piezoelectric crystal

32. Piezoelectric crystal

33. Piezoelectric effect and reverse
piezoelectric effect

34. The microphone (sound to electricity)
and loud speaker (electricity to sound)

35. Sound spectrum
Sound is divided into three major categories:
1-Infrasound ( Frequencies below 20 Hrz)
2-Audible sound (F between 20 and 20 KHrz)
3-Ultrasound (F above 20 khz)
4-Medical ultrasound (F above one MHrz)
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