Basic principles of ultrasonic testing

Сентябрь 14, 2022

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Basic principles of ultrasonic testing

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2. Krautkramer NDT Ultrasonic Systems Examples of oscillation ball on a spring pendulum rotating earth
3. Krautkramer NDT Ultrasonic Systems The ball starts to oscillate as soon as it is pushed
4. Krautkramer NDT Ultrasonic Systems
5. Krautkramer NDT Ultrasonic Systems Movement of the ball over time
6. Krautkramer NDT Ultrasonic Systems Time One full oscillation T Frequency From the duration of one oscillation
7. Krautkramer NDT Ultrasonic Systems 180 360 90 270 Phase Time a 0 The actual displacement a
8. Krautkramer NDT Ultrasonic Systems Spectrum of sound Frequency range Hz Description Example 0 - 20 Infrasound
9. Krautkramer NDT Ultrasonic Systems gas liquid solid Atomic structures low density weak bonding forces medium density
10. Krautkramer NDT Ultrasonic Systems Understanding wave propagation: Spring = elastic bonding force Ball = atom
11. Krautkramer NDT Ultrasonic Systems T distance travelled start of oscillation
12. Krautkramer NDT Ultrasonic Systems T Distance travelled From this we derive: or Wave equation During one
13. Krautkramer NDT Ultrasonic Systems Direction of oscillation Direction of propagation Longitudinal wave Sound propagation
14. Krautkramer NDT Ultrasonic Systems Transverse wave Direction of oscillation Sound propagation
15. Krautkramer NDT Ultrasonic Systems Wave propagation Longitudinal waves propagate in all kind of materials. Transverse waves
16. Krautkramer NDT Ultrasonic Systems Reflection and Transmission As soon as a sound wave comes to a
17. Krautkramer NDT Ultrasonic Systems Behaviour at an interface Medium 1 Medium 2 Interface Incoming wave Transmitted
18. Krautkramer NDT Ultrasonic Systems Reflection + Transmission: Perspex - Steel Incoming wave Transmitted wave Reflected wave
19. Krautkramer NDT Ultrasonic Systems Reflection + Transmission: Steel - Perspex 0,13 1,0 -0,87 Perspex Steel Incoming
20. Krautkramer NDT Ultrasonic Systems Amplitude of sound transmissions: Strong reflection Double transmission No reflection Single transmission
21. Krautkramer NDT Ultrasonic Systems Piezoelectric Effect Piezoelectrical Crystal (Quartz) Battery
22. Krautkramer NDT Ultrasonic Systems The crystal gets thicker, due to a distortion of the crystal lattice
23. Krautkramer NDT Ultrasonic Systems The effect inverses with polarity change Piezoelectric Effect
24. Krautkramer NDT Ultrasonic Systems An alternating voltage generates crystal oscillations at the frequency f U(f) Sound
25. Krautkramer NDT Ultrasonic Systems A short voltage pulse generates an oscillation at the crystal‘s resonant frequency
26. Krautkramer NDT Ultrasonic Systems Reception of ultrasonic waves A sound wave hitting a piezoelectric crystal, induces
27. Krautkramer NDT Ultrasonic Systems Ultrasonic Probes
28. Krautkramer NDT Ultrasonic Systems RF signal (short)
29. Krautkramer NDT Ultrasonic Systems RF signal (medium)
30. Krautkramer NDT Ultrasonic Systems Sound field
31. Krautkramer NDT Ultrasonic Systems Ultrasonic Instrument
32. Krautkramer NDT Ultrasonic Systems Ultrasonic Instrument
33. Krautkramer NDT Ultrasonic Systems Ultrasonic Instrument
34. Krautkramer NDT Ultrasonic Systems Ultrasonic Instrument
35. Krautkramer NDT Ultrasonic Systems Block diagram: Ultrasonic Instrument
36. Krautkramer NDT Ultrasonic Systems Sound reflection at a flaw Probe Flaw Sound travel path Work piece
37. Krautkramer NDT Ultrasonic Systems Plate testing
38. Krautkramer NDT Ultrasonic Systems 0 2 4 6 8 10 s s Wall thickness measurement Corrosion
39. Krautkramer NDT Ultrasonic Systems Through transmission testing
40. Krautkramer NDT Ultrasonic Systems Weld inspection
41. Krautkramer NDT Ultrasonic Systems Straight beam inspection techniques:
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Krautkramer NDT Ultrasonic Systems
Examples of oscillation
ball on a spring
pendulum
rotating earth

Слайд 3

Krautkramer NDT Ultrasonic Systems
The ball starts to oscillate as soon as

it is pushed

Слайд 4

Krautkramer NDT Ultrasonic Systems

Слайд 5

Krautkramer NDT Ultrasonic Systems
Movement of the ball over time

Слайд 6

Krautkramer NDT Ultrasonic Systems
Time
One full oscillation T
Frequency
From the duration of one

oscillation T the frequency f (number of oscillations per second) is calculated:

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Krautkramer NDT Ultrasonic Systems
180
360
90
270
Phase
Time
a
0
The actual displacement a is termed as:

Слайд 8

Krautkramer NDT Ultrasonic Systems
Spectrum of sound
Frequency range Hz
Description
Example
0 - 20
Infrasound
Earth quake
20

- 20.000

Audible sound

Speech, music

> 20.000

Ultrasound

Bat, Quartz crystal

Слайд 9

Krautkramer NDT Ultrasonic Systems
gas
liquid
solid
Atomic structures
low density
weak bonding forces
medium density
medium bonding forces
high

density
strong bonding forces
crystallographic structure

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Krautkramer NDT Ultrasonic Systems
Understanding wave propagation:
Spring = elastic bonding force
Ball =

atom

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Krautkramer NDT Ultrasonic Systems
T
distance travelled
start of oscillation

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Krautkramer NDT Ultrasonic Systems
T
Distance travelled
From this we derive:
or
Wave equation
During one oscillation

T the wave front propagates by the distance λ:

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Krautkramer NDT Ultrasonic Systems
Direction of oscillation
Direction of propagation
Longitudinal wave
Sound propagation

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Krautkramer NDT Ultrasonic Systems
Transverse wave
Direction of oscillation
Sound propagation

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Krautkramer NDT Ultrasonic Systems
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.

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Krautkramer NDT Ultrasonic Systems
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:

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Krautkramer NDT Ultrasonic Systems
Behaviour at an interface
Medium 1
Medium 2
Interface
Incoming wave
Transmitted wave
Reflected

wave

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Krautkramer NDT Ultrasonic Systems
Reflection + Transmission: Perspex - Steel
Incoming wave
Transmitted wave
Reflected

wave

Perspex

Steel

1,87

1,0

0,87

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Krautkramer NDT Ultrasonic Systems
Reflection + Transmission: Steel - Perspex
0,13
1,0
-0,87
Perspex
Steel
Incoming wave
Transmitted wave
Reflected

wave

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Krautkramer NDT Ultrasonic Systems
Amplitude of sound transmissions:
Strong reflection
Double transmission
No reflection
Single

transmission

Strong reflection with inverted phase
No transmission

Water - Steel

Copper - Steel

Steel - Air

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Krautkramer NDT Ultrasonic Systems
Piezoelectric Effect
Piezoelectrical
Crystal (Quartz)
Battery

Слайд 22

Krautkramer NDT Ultrasonic Systems
The crystal gets thicker, due to a distortion

of the crystal lattice

Piezoelectric Effect

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Krautkramer NDT Ultrasonic Systems
The effect inverses with polarity change
Piezoelectric Effect

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Krautkramer NDT Ultrasonic Systems
An alternating voltage generates crystal oscillations at the

frequency f

U(f)

Sound wave with frequency f

Piezoelectric Effect

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Krautkramer NDT Ultrasonic Systems
A short voltage pulse generates an oscillation at

the crystal‘s resonant
frequency f0

Short pulse
( < 1 µs )

Piezoelectric Effect

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Krautkramer NDT Ultrasonic Systems
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

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Krautkramer NDT Ultrasonic Systems
Ultrasonic Probes

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Krautkramer NDT Ultrasonic Systems
RF signal (short)

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Krautkramer NDT Ultrasonic Systems
RF signal (medium)

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Krautkramer NDT Ultrasonic Systems
Sound field

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Krautkramer NDT Ultrasonic Systems
Ultrasonic Instrument

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Krautkramer NDT Ultrasonic Systems
Ultrasonic Instrument

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Krautkramer NDT Ultrasonic Systems
Ultrasonic Instrument

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Krautkramer NDT Ultrasonic Systems
Ultrasonic Instrument

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Krautkramer NDT Ultrasonic Systems
Block diagram: Ultrasonic Instrument

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Krautkramer NDT Ultrasonic Systems
Sound reflection at a flaw
Probe
Flaw
Sound travel path
Work

piece

s

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Krautkramer NDT Ultrasonic Systems
Plate testing

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Krautkramer NDT Ultrasonic Systems
0
2
4
6
8
10
s
s
Wall thickness measurement
Corrosion

Слайд 39

Krautkramer NDT Ultrasonic Systems
Through transmission testing

Слайд 40

Krautkramer NDT Ultrasonic Systems
Weld inspection

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Krautkramer NDT Ultrasonic Systems
Straight beam inspection techniques: