Wavelength and Defect Detection

Question 1

What is the general rule of thumb when detecting discontinuity?

Answer 1

The general rule of thumb is that a discontinuity must be larger than one-half the wavelength to stand a reasonable chance of being detected.

Question 2

Describe what is meant by sensitivity?

Answer 2

Sensitivity is the ability to locate small discontinuities. Sensitivity generally increases with higher frequency (shorter wavelengths).

Question 3

Describe what is meant by resolution?

Answer 3

Resolution is the ability of the system to locate discontinuities that are close together within the material or located near the part surface. Resolution also generally increases as the frequency increases.

Question 4

Before selecting an inspection frequency what should be considered?

Answer 4

The material’s grain structure and thickness, and the discontinuity’s type, size, and probable location should be considered