Dakota Ultrasonics DFX-8 plus MANUAL1 - Manual (Page 83)

DFX-8 Series Ultrasonic Flaw Detectors
79
Where:
N = Near Field Length
D
EFF
= Effective Diameter
= Wave Length (velocity/frequency)
In order to approximate the effective diameter, the shape of the crystal must be taken
into account. Transducers are either round or square/rectangular in shape, and can
be approximated as follows:
Round Crystal (D
EFF
)
Where:
D
EFF
= Effective Diameter
Dia. = Diameter of the crystal
0.97 = Fixed ratio
Square/Rectangle (D
EFF
)
Where:
K = Aspect Ratio
A = Largest Dimension
B = Smallest Dimension
Where: