1. Prepared By: GUNDALE MANSI V.
GUIDED BY:
MR. ANIL PARMR
ASST. PROF. MECHANICAL
ITM UNIVERSE
VADODARA

2. Basic Principles of Ultrasonic Testing
Theory and Practice

3. Examples of oscillation
ball on a spring
pendulum
rotating earth

4. The ball starts to oscillate as soon as it is pushed
Pulse
The ball starts to oscillate as soon as it is pushed

5. Oscillation

6. Movement of the ball over time

7. One full oscillation T Frequency Time
From the duration of one oscillation T the frequency f (number of oscillations per second) is calculated:
One full oscillation T

8. The actual displacement a is termed as:
Time 90
180
270
360
Phase

9. Spectrum of sound 0 - 20 Infrasound Earth quake 20 - 20.000
Frequency range Hz
Description
Example
0 - 20
Infrasound
Earth quake
Audible sound
Speech, music
>
Ultrasound
Bat, Quartz crystal

10. Atomic structures gas liquid solid low density weak bonding forces
medium density
medium bonding forces
high density
strong bonding forces
crystallographic structure

11. Understanding wave propagation:
Ball = atom
Spring = elastic bonding force

12. start of oscillation T
distance travelled

13. During one oscillation T the wave front propagates by the distance :
Distance travelled
From this we derive:
Wave equation or

14. Direction of propagation
Sound propagation
Longitudinal wave
Direction of propagation
Direction of oscillation

15. Direction of propagation
Sound propagation
Transverse wave
Direction of oscillation
Direction of propagation

16. Wave propagation
Longitudinal waves propagate in all kind of materials.
Transverse waves only propagate in solid bodies.
Due to the different type of oscillation, transverse waves travel at lower speeds.
Sound velocity mainly depends on the density and E-modulus of the material.
Air Water Steel, long Steel, trans
330 m/s
1480 m/s
3250 m/s
5920 m/s

17. Reflection and Transmission
As soon as a sound wave comes to a change in material characteristics ,e.g. the surface of a workpiece, or an internal inclusion, wave propagation will change too:

18. Reflected wave Behaviour at an interface Incoming wave
Medium 1
Medium 2
Incoming wave
Transmitted wave
Reflected wave
Interface

19. Reflection + Transmission: Perspex - Steel
1,87
Incoming wave
1,0
Transmitted wave
0,87
Reflected wave
Perspex
Steel

20. Reflection + Transmission: Steel - Perspex
Incoming wave
Transmitted wave
1,0
0,13
-0,87
Reflected wave
Steel
Perspex

21. Amplitude of sound transmissions:
Water - Steel
Copper - Steel
Steel - Air
Strong reflection
Double transmission
No reflection
Single transmission
Strong reflection with inverted phase
No transmission

22. Piezoelectric Effect +
Battery
Piezoelectrical
Crystal (Quartz)

23. + Piezoelectric Effect
The crystal gets thicker, due to a distortion of the crystal lattice

24. Piezoelectric Effect +
The effect inverses with polarity change

25. Sound wave with frequency f
Piezoelectric Effect
Sound wave with frequency f
U(f)
An alternating voltage generates crystal oscillations at the frequency f

26. Piezoelectric Effect Short pulse ( < 1 µs )
A short voltage pulse generates an oscillation at the crystal‘s resonant
frequency f0

27. Reception of ultrasonic waves
A sound wave hitting a piezoelectric crystal, induces crystal vibration which then causes electrical voltages at the crystal surfaces.
Electrical
energy
Piezoelectrical crystal
Ultrasonic wave

28. Ultrasonic Probes Delay / protecting face socket Electrical matching
crystal
Damping
Delay / protecting face
Electrical matching
Cable
Straight beam probe
Angle beam probe
TR-probe

29. RF signal (short)
100 ns

30. RF signal (medium)

31. Sound field Near field Far field Focus Angle of divergence Crystal
Accoustical axis D0 6

32. Ultrasonic Instrument2 4 8 10 6

33. Ultrasonic Instrument2 4 8 10 6 + - U h

34. Ultrasonic Instrument2 4 8 10 6 + - U h

35. Ultrasonic Instrument2 4 8 10 6 + - U h v

36. Block diagram: Ultrasonic Instrument
amplifier
work piece
probe
horizontal
sweep
clock
pulser IP BE
screen

37. Sound reflection at a flaw
Probe
Sound travel path
Flaw
Work piece

38. Plate testing plate IP = Initial pulse F = Flaw BE = Backwall echo 2 4
delamination
plate 2 4 6 8 10 IP F BE
IP = Initial pulse
F = Flaw
BE = Backwall echo

39. Wall thickness measurement
Corrosion 2 4 6 8 10

40. Through transmission signal
Through transmission testing 2 4 6 8 10
Through transmission signal 1 T R
Flaw

41. Work piece with welding
Weld inspection 20 40 60 80
100 s a a' d x
a = s sinß
a' = a - x
d' = s cosß
d = 2T - t'
Lack of fusion
Work piece with welding F
ß = probe angle
s = sound path
a = surface distance
a‘ = reduced surface distance
d‘ = virtual depth
d = actual depth
T = material thickness ß

42. Straight beam inspection techniques:
Direct contact,
single element probe
dual element probe
Fixed delay
Immersion testing
Through transmission

43. Immersion testing 1 2 1 surface = sound entry water delay backwall
flaw 2 4 6 8 10 IE IP BE F 1