teori dasar ultrasonik

Krautkramer NDT Ultrasonic Systems

Introduction toUltrasonic Testing

SD 218

Introduction toUltrasonic Testing

SD 218© SLAMET WALUYO

PT. MULTI KHARISMA PERKASA2007


socket

matching-element

damping-block

crystalprotecting face(probe delay)

housing

workpiece Sound pulse

Straight beam probe


crystal

perspex wedge(probe delay)

damping blocks

socket

housing

workpiece Sound pulse

Angle beam probe


near field

far field

acoustical axis (central beam)

N = near field length

= angle of divergence

3

Sound field


Flaw detection


10 20 30 40

Flaw detection


Bad flaw orientation


crack

Improper flaw location


10 20 30 40

crack

Angle reflection


Angle reflection


10 20 30 40

Vertical, near surface flaw


10 155 10 155T R

a1

Tandem technique (top)


10 155 10 155T R

a 2

Tandem technique (middle)


10 155 10 155T R

a 3

Tandem technique (bottom)


10 20 30 40

Improper flaw orientation


10 20 30 40

Perfect flaw orientation


sound beam

flat defect

15105

reflected sound waves

Flaw detectability with improper flaw orientation


s

Flaw distance


start signal(pulse)

finish signal(echo)

transmitter

transit timemeasurement

probe

work piece

sound transitpath

Stop-watch

Principle of transit time measurement


0 2 4 6 8 10

CRT / A-scan display


0 2 4 6 8 10

work piece

probe

sound wave starts at crystal

light point

transmittertransmittertransmission

pulse

Priciple, transmission pulse


0 2 4 6 8 10

work piece

probe

sound wave

transmittertransmitter

Priciple, sound wave in the workpiece


0 2 4 6 8 10

work piece

probe


Priciple, sound pulse at the back wall


0 2 4 6 8 10

work piece

probe


Priciple, sound pulse at the coupling surface


0 2 4 6 8 10

work piece

probe

back wallecho


Priciple, echo display and 2nd run


2 4 6 8 10

protecting face

crystal

probe

electricalzero

(initial pulse)

mechanicalzero

(surface)

Probe delay


electicalzero

(initial pulse)

mechanicalzero

(surface)sound wave

work piece

delay(wedge)

probe 0 2 4 6 8 10

Probe delay


0 2 4 6 8 10

work piece

probeback wall

echo

flaw

flawecho

Flaw location and echo display


0 2 4 6 8 10

work piece

probe

back wallecho

flaw

flawecho



0 2 4 6 8 10

flaw echocoveredby initialpulse

work piece

probe

back wallecho

flaw



0 2 4 6 8 10

back wallecho:

without

with flaw

work piece

probe

flaw



0 2 4 6 8 10

flaw echosequence

work piece

probe

flaw



0 2 4 6 8 10

dead zone

Dead zone


10 20

Near surface detectability with angle beam pobes


receiversocket

transmittersocket

damping blocks

crystal

delay

acousticalbarrier

TR-probe / dual crystal probe


0 2 4 6 8 10

IP

BE

work piece

TR-probe

Probe delay with TR-probes


0 2 4 6 8 10

IP

BE

flaw

cross talkecho

flawecho

TR-probe

Cross talk at high gain


0 2 4 6 8 10

0 100 mm50

steel, L

div.

Range calibration


5 10 15

70°

45°

100

mm

60°

Calibration block 1 with angle beam probes


5 10 15

0 2 4 6 8 10

100 mm

1st echo from circular section


5 10 15

0 2 4 6 8 10

100 mm 200 mm 300 mm

Echo sequence from 100 mm radius


s = 25 mms = 100 mms = 175 mmetc.

1

2

3

this wave will be absorbed !

25 mm radius of calibration block 2


s = 50 mms = 125 mms = 200 mmetc.

1

2

3

50 mm radius of calibration block 2


5 10 15

0 2 4 6 8 10

0 100 mmsteel

100 mm range calibration on K2


51015

work piece reflector

s

0 2 4 6 8 10

s = k•R

s = sound pathk = scale factorR = screen reading

Flaw location


flaw location

a

s d

Sound entry point projectionpoint

a = s•sin ßd = s•cos ß

ß

ßß = probe angles = sound patha = surface distanced = depth

"flaw triangle"

Flaw location with angle beam probes


51015

work piece reflector

aa'

s d

x

index point -front edge of probe

a = surface distancea' = reduced surface distancex = x-value = distance:

Flaw location with angle beam probes


51015

apparent flaw location

a

sd = apparent depth

T

Flaw location with an angle beam probe on a plate


51015

apparent flaw location

real flaw location

a

s d

d'

d' = apparent depthd = real depthT = work piece thickness

T

a = s • sind‘ = s • cosd = 2T - d

a = s • sind‘ = s • cosd = 2T - d

Flaw location with an angle beam probe on a plate


Large defects parallel to the scanning surface


Scanning the edge of the defect

Flaw echo drops to 50% of its maximum value


0 2 4 6 8 100 2 4 6 8 10 0 2 4 6 8 10

IP BER IP BER IP BER

Flaw sizes and echo amplitudes


0 2 4 6 8 10

0 2 4 6 8 10

0 2 4 6 8 10

IP BER

IP BER

IP BER

Flaw distances and echo amplitudes


0 2 4 6 8 10

IP BEF

F

instrument gain: G = 34 dB

80 %

Defect evaluation by comparison - 1


0 2 4 6 8 10

IP BER

instrument gain: 34 dB



0 2 4 6 8 10

IP BERE

+ 8 dB

instrument gain: 42 dB


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