Basic Principles Ultrasonic Krautkramer

Basic Principles Principles of Ultrasonic Ultrasonic Testing Testing

Krautkramer NDT Ultrasonic Systems

Basic Principles Principles of Ultrasonic Ultrasonic Testing Testing xamp es o osc a on a spring

earth


Basic Principles Principles of Ultrasonic Ultrasonic Testing Testing xamp es o osc a on a spring

earth



The ball starts to oscillate as soon as it is ushed Krautkramer NDT Ultrasonic Systems



Basic Principles of Ultrasonic Testing Movement of the ball over time


Basic Principles of Ultrasonic Testing Fre uenc

Time

From the duration of one oscillation e requency num er o oscillations per second) is calculated:

One full osc a on


Basic Principles of Ultrasonic Testing The actual displacement a is termed as:

a Time

0

90

180

270

360 Phase


Basic Principles of Ultrasonic Testing Spectrum of sound Fre uenc ran e Hz

Exam le

Descri tion

-

20 - 20.000 >

.

Audible sound trasoun


Speech, music at,

uartz crysta

Basic Principles of Ultrasonic Testing om c s ruc ures

• low density •

• medium density • forces


• high density • • crystallographic structure

Basic Principles of Ultrasonic Testing n ers an ng wave propaga on:

Ball = atom

Spring = elastic bonding force


Basic Principles of Ultrasonic Testing

T


Basic Principles of Ultrasonic Testing

During one oscillation T the wave ron propaga es y e s ance :

Distance travelled

From this we derive: or

Wave equation Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing Sound propagation

Longitudinal wave

Direction of propagation

Direction of oscillation


Basic Principles of Ultrasonic Testing Sound propagation Transverse wave Direction of oscillation

Direction of propagation


Basic Principles of Ultrasonic Testing Wave propagation Transverse waves only propagate in solid bodies. Due to the different t e of oscillation transverse waves travel at lower speeds. Sound velocity mainly depends on the density and Emo u us o e ma er a . Air Water Steel, long Steel, trans

330 m/s 1480 m/s 5920 m/s 3250 m/s


Basic Principles of Ultrasonic Testing Reflection and Transmission s soon as a soun wave comes o a c ange n ma er a characteristics ,e.g. the surface of a workpiece, or an internal inclusion, wave propagation will change too:


Basic Principles of Ultrasonic Testing e av our a an n er ace Medium 1

Medium 2

w v

w v

Reflected wave Interface


Basic Principles of Ultrasonic Testing Reflection + Transmission: Perspex - Steel 1,87

, 0,87

Reflected wave

Perspex

Steel Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing Reflection + Transmission: Steel - Perspex

Transmitted wave

Incoming wave , ,

-0,87 e ec e wave

Perspex Krautkramer NDT Ultrasonic Systems

Steel

Basic Principles of Ultrasonic Testing mp u e o soun

Water - Steel

ransm ss ons:

Co

er - Steel

• Strong reflection • No reflection • Double transmission • Single transmission


Steel - Air • Strong reflection w nver e p ase • No transmission

Basic Principles of Ultrasonic Testing ezoe ec r c

ec

Batter

Piezoelectrical Crystal (Quartz) Krautkramer NDT Ultrasonic Systems


ec

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


ec

The effect inverses with polarity change Krautkramer NDT Ultrasonic Systems


ec

oun wave with frequency f

U(f)

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


ec

Short pulse ( < 1 µs )

A short voltage pulse generates an oscillation at the crystal‘s resonant fre uenc f Krautkramer NDT Ultrasonic Systems

Basic Principles of Ultrasonic Testing ecep on o u rason c waves , vibration which then causes electrical voltages at the crystal surfaces. Electrical energy

crystal


rason c wave

Basic Principles of Ultrasonic Testing Ultrasonic Probes Electrical matching Cable

crystal Dam in

Strai ht beam robe

TR- robe


An le beam robe

Basic Principles of Ultrasonic Testing RF signal (short)

ns


Basic Principles of Ultrasonic Testing RF signal (medium)


Basic Principles of Ultrasonic Testing Sound field

Focus

Crystal

Angle of divergence 6

N

Near field

Far field


Basic Principles of Ultrasonic Testing Ultrasonic Instrument



Uh



Uh

0

2

4

6

8

10


Basic Principles of Ultrasonic Testing Ultrasonic Instrument + Uv

-

+ Uh


Basic Principles of Ultrasonic Testing Block diagram: Ultrasonic Instrument amplifier

IP

screen BE

probe work iece Krautkramer NDT Ultrasonic Systems

horizontal sweep

Basic Principles of Ultrasonic Testing Sound reflection at a flaw s

Sound travel path

Work piece


Flaw

Basic Principles of Ultrasonic Testing Plate testing IP BE

F

late

delamination

0

2

4

6

8

IP = Initial pulse F = Flaw =


ac wa ec o

10

Basic Principles of Ultrasonic Testing Wall thickness measurement

s s


Basic Principles of Ultrasonic Testing Through transmission testing Through transmission signal

1

T

R

1

2

0

Flaw


2

4

6

8

10

Basic Principles of Ultrasonic Testing Weld inspection a = s sinß

F

'

s

-

d' = s cosß 0

20

40

60

80

100

d = 2T - t'

a a'

x

Work piece with welding

s

Lack of fusion


= s = sound path a = surface distance a‘ = reduced surface distance ‘= d = actual depth T = material thickness

Basic Principles of Ultrasonic Testing Straight beam inspection techniques: Direct contact,

Direct contact,

single element probe

dual element probe

Through transmission

Immersion testing


Basic Principles Ultrasonic Krautkramer

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