1. Velocity of Ultrasonic Waves in a medium (V) = f x l

OR

W here

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. A coustic Impedance (Z) = V x r

W here:

Z=

Acoustic Impedance

r=

D ensity

V=

Velocity

3. R eflection Coefficient

W here:

R = Reflection Coefficient

Z1 = A coustic Impedance of Medium 1

Z2 = A coustic Impedance of Medium 2

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4. Transmission coefficient

T = 4 Z1Z2/ (Z1+Z2)2

W here:

R = Reflection Coefficient

Z1 = Acoustic Impedance of Medium 1

Z2 = Acoustic Impedance of Medium 2

5. Longitudinal Wave Velocity

W here:

VL =

E=

r=

m=

Longitudinal Wave Velocity

Modulus of Elasticity

Density

Poisson's Ratio

6. Shear Wave Velocity

W here:

Vs =

E=

r=

m=

G=

Shear Wave Velocity

Modulus of Elasticity

Density

Poisson's Ratio

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 =

qR =

V1 =

V2 =

Angle of the Incident Wave

Angle of the Reflected Wave

Velocity of Incident Wave

Velocity of Reflected Wave

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8. Near Field

Where:

N

D

l

V

=

=

=

=

Near Field

Transducer Diameter

W avelength

Velocity

9. Beam Spread Half Angle

Where:

l

D

V

F

=

=

=

=

Wavelength

Transducer Diameter

Velocity

Frequency

10. Decibel (dB) Gain or Loss

Where:

dB = Decibel

P1 = Pressure Amplitude 1

P2 = Pressure Amplitude 2

11. Angle Beam testing of Pipe

t=

d(1- Sin Ø)

2

S in Ø = 1-

2t

d

d = O.D. of Pipe

t = Maximum wall thickness

Ø = Probe angle

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12. Formulae for Angle Beam Calculations

β = Sound beam refracted angle in the test material

T = Thickness of the test material

Skip Distance

S = 2T x tan β

V-Path Length

2T

cosβ

V-Path =

Leg Length

T

cosβ

Leg =

Surface Distnace

SD = sinβ x Soundpath Length

Depth in First Leg

Depth (1st L eg) = cosβ x Sound path Length

Depth in Second Leg

D epth (2nd Leg) = 2T – (cosβ x S ound path Length)

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2011-12

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For refererence only. ‘TINT’ is not responsible for errors and omissions in the data if any.