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Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Basic Principles of Ultrasonic Testing Theory and Practice

Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

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Page 1: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

Basic Principles ofUltrasonic Testing

Theory and Practice

Page 2: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingExamples of oscillation

ball ona spring

pendulum rotatingearth

Page 3: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

The ball starts to oscillate as soon as it is pushed

Pulse

Page 4: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

Oscillation

Page 5: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingMovement of the ball over time

Page 6: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

Time

One full oscillation T

Frequency

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

f1

T

f1

Page 7: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

180 36090 270

Phase

Time

a

0

The actual displacement a is termed as: sin A a sin A a

Page 8: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingSpectrum 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

Page 9: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

gas liquid solid

Atomic structures

• low density• weak bonding forces

• medium density• medium bonding

forces

• high density • strong bonding forces• crystallographic

structure

Page 10: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingUnderstanding wave propagation:

Spring = elastic bonding forceBall = atom

Page 11: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

T

distance travelled

start of oscillation

Page 12: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

T

Distance travelled

From this we derive:

or Wave equation

During one oscillation T the wave front propagates by the distance :

Tc

Tc f c f c

Page 13: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

Direction of oscillation

Direction of propagationLongitudinal wave

Sound propagation

Page 14: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

Direction of propagationTransverse waveDirection of oscillation

Sound propagation

Page 15: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingWave propagation

AirWaterSteel, longSteel, trans

330 m/s

1480 m/s

3250 m/s

5920 m/s

Longitudinal waves propagate in all kind of materials.Transverse waves only propagate in solid bodies. Due to the different type of oscillation, transverse wavestravel at lower speeds.Sound velocity mainly depends on the density and E-modulus of the material.

Page 16: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingReflection 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:

Page 17: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingBehaviour at an interface

Medium 1 Medium 2

Interface

Incoming wave Transmitted wave

Reflected wave

Page 18: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingReflection + Transmission: Perspex - Steel

Incoming wave Transmitted wave

Reflected wave

Perspex Steel

1,87

1,00,87

Page 19: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingReflection + Transmission: Steel - Perspex

0,13

1,0

-0,87

Perspex Steel

Incoming wave Transmitted wave

Reflected wave

Page 20: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingAmplitude of sound transmissions:

• Strong reflection• Double transmission

• No reflection• Single transmission

• Strong reflection with inverted phase

• No transmission

Water - Steel Copper - Steel Steel - Air

Page 21: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingPiezoelectric Effect

Piezoelectrical Crystal (Quartz)

Battery

+

Page 22: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

+

The crystal gets thicker, due to a distortion of the crystal lattice

Piezoelectric Effect

Page 23: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

+

The effect inverses with polarity change

Piezoelectric Effect

Page 24: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

An alternating voltage generates crystal oscillations at the frequency f

U(f)

Sound wave with

frequency f

Piezoelectric Effect

Page 25: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

A short voltage pulse generates an oscillation at the crystal‘s resonant

frequency f0

Short pulse ( < 1 µs )

Piezoelectric Effect

Page 26: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingReception 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

Page 27: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingUltrasonic Probes

socket

crystal

Damping

Delay / protecting faceElectrical matchingCable

Straight beam probe Angle beam probeTR-probe

Page 28: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

100 ns

RF signal (short)

Page 29: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingRF signal (medium)

Page 30: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

N

Near field Far field

Focus Angle of divergenceCrystalAccoustical axis

D0

6

Sound field

Page 31: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingUltrasonic Instrument

0 2 4 8 106

Page 32: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

0 2 4 8 106

+-Uh

Ultrasonic Instrument

Page 33: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

0 2 4 8 106

+ -Uh

Ultrasonic Instrument

Page 34: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

0 2 4 8 106

+

+

-

-

U

U

h

v

Ultrasonic Instrument

Page 35: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingBlock diagram: Ultrasonic Instrument

amplifier

work piece

probe

horizontal

sweep

clock

pulser

IP

BE

screen

Page 36: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingSound reflection at a flaw

Probe

Flaw Sound travel path

Work piece

s

Page 37: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingPlate testing

delaminationplate 0 2 4 6 8 10

IP

F

BE

IP = Initial pulse

F = Flaw

BE = Backwall echo

Page 38: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

0 2 4 6 8 10

s

s

Wall thickness measurement

Corrosion

Page 39: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingThrough transmission testing

0 2 4 6 8 10

Through transmission signal

1

2

1

2

T

T

R

R

Flaw

Page 40: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingWeld inspection

0 20 40 60 80 100

s

aa'

d

x

a = s sinßa = s sinß

a' = a - xa' = a - x

d' = s cosßd' = s cosß

d = 2T - t'd = 2T - t'

s

Lack of fusion

Work piece with welding

Fß = probe angles = sound patha = surface distancea‘ = reduced surface distanced‘ = virtual depthd = actual depthT = material thickness

ß

Page 41: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic TestingStraight beam inspection techniques:

Direct contact,

single element probe

Direct contact,

dual element probeFixed delay

Immersion testingThrough transmission

Page 42: Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice

Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing

surface = sound entry

backwall flaw

1 2

water delay

0 2 4 6 8 10 0 2 4 6 8 10

IE IEIP IP

BE BEF

1 2

Immersion testing