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

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Presentation on theme: "Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Basic Principles of Ultrasonic Testing Theory and Practice."— Presentation transcript:

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

2 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Examples of oscillation ball on a spring pendulum rotating earth

3 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems The ball starts to oscillate as soon as it is pushed Pulse

4 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Oscillation

5 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Movement of the ball over time

6 Basic Principles of Ultrasonic Testing 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:

7 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Phase Time a 0 The actual displacement a is termed as:

8 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Spectrum of sound Frequency range HzDescription Example Infrasound Earth quake Audible soundSpeech, music > UltrasoundBat, Quartz crystal

9 Basic Principles of Ultrasonic Testing 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

10 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Understanding wave propagation: Spring = elastic bonding forceBall = atom

11 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems T distance travelled start of oscillation

12 Basic Principles of Ultrasonic Testing 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 :

13 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Direction of oscillation Direction of propagationLongitudinal wave Sound propagation

14 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Direction of propagation Transverse wave Direction of oscillation Sound propagation

15 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Wave propagation Air Water Steel, long Steel, 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 waves travel at lower speeds. Sound velocity mainly depends on the density and E- modulus of the material.

16 Basic Principles of Ultrasonic Testing 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:

17 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Behaviour at an interface Medium 1Medium 2 Interface Incoming waveTransmitted wave Reflected wave

18 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Reflection + Transmission: Perspex - Steel Incoming wave Transmitted wave Reflected wave PerspexSteel 1,87 1,0 0,87

19 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Reflection + Transmission: Steel - Perspex 0,13 1,0 -0,87 Perspex Stee l Incoming wave Transmitted wave Reflected wave

20 Basic Principles of Ultrasonic Testing 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 - SteelSteel - Air

21 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Piezoelectric Effect Piezoelectrical Crystal (Quartz) Battery +

22 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems + The crystal gets thicker, due to a distortion of the crystal lattice Piezoelectric Effect

23 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems + The effect inverses with polarity change Piezoelectric Effect

24 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems An alternating voltage generates crystal oscillations at the frequency f U(f) Sound wave with frequency f Piezoelectric Effect

25 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems A short voltage pulse generates an oscillation at the crystals resonant frequency f 0 Short pulse ( < 1 µs ) Piezoelectric Effect

26 Basic Principles of Ultrasonic Testing 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

27 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Ultrasonic Probes socket crystal Damping Delay / protecting face Electrical matching Cable Straight beam probeAngle beam probeTR-probe

28 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems 100 ns RF signal (short)

29 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems RF signal (medium)

30 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems N Near fieldFar field FocusAngle of divergence Crystal Accoustical axis D0D0 6 Sound field

31 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Ultrasonic Instrument

32 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems U h Ultrasonic Instrument

33 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems U h Ultrasonic Instrument

34 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems U U h v Ultrasonic Instrument

35 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Block diagram: Ultrasonic Instrument amplifier work piece probe horizontal sweep clock pulser IP BE screen

36 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Sound reflection at a flaw Probe Flaw Sound travel path Work piece s

37 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Plate testing delamination plate IP F BE IP = Initial pulse F = Flaw BE = Backwall echo

38 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems s s Wall thickness measurement Corrosion

39 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Through transmission testing Through transmission signal T T R R Flaw

40 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Weld inspection s a a' d x a = s sinß a' = a - x d' = s cosß d = 2T - t' s 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

41 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Straight beam inspection techniques: Direct contact, single element probe Direct contact, dual element probe Fixed delay Immersion testingThrough transmission

42 Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems surface = sound entry backwall flaw 12 water delay IE IP BE F 1 2 Immersion testing


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