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Basic principles us_presentation

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Ultrasonic testing

Ultrasonic testing

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    Basic principles us_presentation Basic principles us_presentation Presentation Transcript

    • Basic Principles of Ultrasonic Testing Basic Principles of Ultrasonic Testing Theory and Practice Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingExamples of oscillationball on pendulum rotatinga spring earth Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic Testing Pulse The ball starts to oscillate as soon as it is pushed Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic Testing Oscillation Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingMovement of the ball over time Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic Testing Frequency Time From the duration of one oscillation One full T the frequency f (number of oscillation T oscillations per second) is calculated: 1 f = T Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic Testing The actual displacement a is termed as: a = A sin ϕ a Time 0 90 180 270 360 Phase Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingSpectrum of soundFrequency range Hz Description Example 0 - 20 Infrasound Earth quake 20 - 20.000 Audible sound Speech, music > 20.000 Ultrasound Bat, Quartz crystal Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingAtomic structures gas liquid solid• low density • medium density • high density• weak bonding forces • medium bonding • strong bonding forces forces • crystallographic structure Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingUnderstanding wave propagation:Ball = atom Spring = elastic bonding force Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic Testing star t of o scT illat ion distance travelled Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic Testing During one oscillation T the wave T front propagates by the distance λ: Distance travelled From this we derive: or Wave equation c= λ c = λf T Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingSound propagation Longitudinal wave Direction of propagation Direction of oscillation Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingSound propagation Transverse wave Direction of propagation Direction of oscillation Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingWave propagationLongitudinal 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.Air 330 m/sWater 1480 m/sSteel, long 5920 m/sSteel, trans 3250 m/s Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingReflection and TransmissionAs soon as a sound wave comes to a change in materialcharacteristics ,e.g. the surface of a workpiece, or an internalinclusion, wave propagation will change too: Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingBehaviour at an interface Medium 1 Medium 2 Incoming wave Transmitted wave Reflected wave Interface Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingReflection + Transmission: Perspex - Steel 1,87 Incoming wave 1,0 Transmitted wave 0,87 Reflected wave Perspex Steel Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingReflection + Transmission: Steel - Perspex Incoming wave Transmitted wave 1,0 0,13 -0,87 Reflected wave Perspex Steel Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingAmplitude of sound transmissions: Water - Steel Copper - Steel Steel - Air• Strong reflection • No reflection • Strong reflection• Double transmission • Single transmission with inverted phase • No transmission Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingPiezoelectric Effect + Battery Piezoelectrical Crystal (Quartz) Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingPiezoelectric Effect + The crystal gets thicker, due to a distortion of the crystal lattice Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingPiezoelectric Effect + The effect inverses with polarity change Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingPiezoelectric Effect Sound wave with frequency f U(f)An alternating voltage generates crystal oscillations at the frequency f Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingPiezoelectric Effect Short pulse ( < 1 µs )A short voltage pulse generates an oscillation at the crystal‘s resonantfrequency f0 Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingReception of ultrasonic wavesA sound wave hitting a piezoelectric crystal, induces crystalvibration which then causes electrical voltages at the crystalsurfaces. Electrical Piezoelectrical crystal Ultrasonic wave energy Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingUltrasonic Probes socket Delay / protecting face crystal Electrical matching Damping Cable Straight beam probe TR-probe Angle beam probe Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingRF signal (short) 100 ns Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingRF signal (medium) Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingSound field Crystal Focus Angle of divergence Accoustical axis γ6 D0 N Near field Far field Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingUltrasonic Instrument 0 2 4 6 8 10 Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingUltrasonic Instrument - + Uh 0 2 4 6 8 10 Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingUltrasonic Instrument + - Uh 0 2 4 6 8 10 Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingUltrasonic Instrument + Uv - + - Uh 0 2 4 6 8 10 Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingBlock diagram: Ultrasonic Instrument amplifier screen IP horizontal BE sweep clock pulser probe work piece Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingSound reflection at a flaw s Probe Sound travel path Flaw Work piece Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingPlate testing IP BE F delamination 0 2 4 6 8 10 plate IP = Initial pulse F = Flaw BE = Backwall echo Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingWall thickness measurement s s Corrosion 0 2 4 6 8 10 Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingThrough transmission testing Through transmission signal1 T R 12 T R 2 0 2 4 6 8 10 Flaw Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingWeld inspection a = s sinß F a = a - x ß = probe angle s s = sound path a = surface distance d = s cosß a‘ = reduced surface distance d‘ = virtual depth 0 20 40 60 80 100 d = 2T - t d = actual depth T = material thickness a x a ß d Lack of fusion Work piece with welding s Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingStraight beam inspection techniques: Direct contact, Direct contact, Fixed delay single element probe dual element probe Through transmission Immersion testing Krautkramer NDT Ultrasonic Systems
    • Basic Principles of Ultrasonic TestingImmersion testing 1 2 surface = water delaysound entry backwall flaw IP 1 IP IE IE 2 BE BE F 0 2 4 6 8 10 0 2 4 6 8 10 Krautkramer NDT Ultrasonic Systems