Basic Principles UT Presentation - Theory & Practice
- 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: T f 1 f = 1/T
- 7. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems 180 360 90 270 Phase Time a 0 The actual displacement a is termed as: sinA a
- 8. Basic Principles of Ultrasonic Testing 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
- 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 force Ball = 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 : T c f c
- 13. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Direction of oscillation Direction of propagation Longitudinal 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 1 Medium 2 Interface Incoming wave Transmitted wave Reflected wave
- 18. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Reflection + Transmission: Perspex - Steel Incoming wave Transmitted wave Reflected wave Perspex Steel 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 Steel 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 - Steel Steel - 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 crystal‘s resonant frequency f0 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 probe Angle beam probe TR-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 field Far field Focus Angle of divergence Crystal Accoustical axis D0 6 Sound field
- 31. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Ultrasonic Instrument 0 2 4 8 10 6
- 32. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems 0 2 4 8 10 6 + - Uh Ultrasonic Instrument
- 33. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems 0 2 4 8 10 6 + - Uh Ultrasonic Instrument
- 34. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems 0 2 4 8 10 6 + + - - 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 0 2 4 6 8 10 IP F BE IP = Initial pulse F = Flaw BE = Backwall echo
- 38. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems 0 2 4 6 8 10 s s Wall thickness measurement Corrosion
- 39. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Through transmission testing 0 2 4 6 8 10 Through transmission signal 1 2 1 2 T T R R Flaw
- 40. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems Weld inspection 0 20 40 60 80 100 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 testing Through transmission
- 42. Basic Principles of Ultrasonic Testing Krautkramer NDT Ultrasonic Systems surface = sound entry backwall flaw 1 2 water delay 0 2 4 6 8 10 0 2 4 6 8 10 IE IE IP IP BE BE F 1 2 Immersion testing