Ultrasonic testing useful formulae - Trinity NDT

1 Ultrasonic testing (UT) useful formulae . 1. Velocity of Ultrasonic Waves in a medium (V) = f x l OR. Where f = Number of cycles per second is called frequency. Measured in Hertz'. Abbreviated as Hz'. One Hertz is equivalent to One cycle per second l = Distance covered in one cycle is wavelength V= Velocity of Ultrasonic wave inside the medium in mm/s'. 2. Acoustic Impedance (Z) = V x r Where: Z= Acoustic Impedance r= Density V= Velocity 3. Reflection Coefficient Where: R = Reflection Coefficient Z1 = Acoustic Impedance of Medium 1. Z2 = Acoustic Impedance of Medium 2.. Trinity NDT. Material testing & NDT I Training& Certification I Consulting Visit us: Page 1 of 4.

2 2011-12 For refererence only. TINT' is not responsible for errors and omissions in the data if any. 4. Transmission coefficient T = 4 Z1Z2/ (Z1+Z2)2. Where: R = Reflection Coefficient Z1 = Acoustic Impedance of Medium 1. Z2 = Acoustic Impedance of Medium 2. 5. Longitudinal Wave Velocity Where: VL = Longitudinal Wave Velocity E = Modulus of Elasticity r = Density m = Poisson's Ratio 6. Shear Wave Velocity Where: Vs = Shear Wave Velocity E = Modulus of Elasticity r = Density m = Poisson's Ratio G= Shear Modulus 7. Refraction - Snell's Law: That is the ratio of sine of the angle to the respective wave velocities are proportional. Where: qI = Angle of the Incident Wave qR = Angle of the Reflected Wave V1 = Velocity of Incident Wave V2 = Velocity of Reflected Wave.

3 Trinity NDT. Material testing & NDT I Training& Certification I Consulting Visit us: Page 2 of 4. 2011-12 For refererence only. TINT' is not responsible for errors and omissions in the data if any. 8. Near Field Where: N = Near Field D = Transducer Diameter l = Wavelength V = Velocity 9. Beam Spread Half Angle Where: l = Wavelength D = Transducer Diameter V = Velocity F = Frequency 10. Decibel (dB) Gain or Loss Where: dB = Decibel P1 = Pressure Amplitude 1. P2 = Pressure Amplitude 2. 11. Angle Beam testing of Pipe d(1- Sin ). t=. 2. 2t Sin = 1- d d = of Pipe t = Maximum wall thickness = Probe angle . Trinity NDT. Material testing & NDT I Training& Certification I Consulting Page 3 of 4.

4 Visit us: 2011-12 For refererence only. TINT' is not responsible for errors and omissions in the data if any. 12. formulae for Angle Beam Calculations = Sound beam refracted angle in the test material T = Thickness of the test material Skip Distance S = 2T x tan . V-Path Length 2T. V-Path =. cos . Leg Length T. Leg =. cos . Surface Distnace SD = sin x Soundpath Length Depth in First Leg Depth (1st Leg) = cos x Sound path Length Depth in Second Leg Depth (2nd Leg) = 2T (cos x Sound path Length).. Trinity NDT. Material testing & NDT I Training& Certification I Consulting Plot No. V-22(A), 2nd Stage, Peenya Industrial Estate, Bangalore - 560 058, INDIA.

5 Phone: +91 99009 29439, 98441 29439, Telefax: +91-80-28366466, e-mail: Visit us: Page 4 of 4. 2011-12 For refererence only. TINT' is not responsible for errors and omissions in the data if any.