WIDTH ESTIMATION FOR SHORT, DEEP DEFECTS

Estimating defect width is not straightforward. This is because the signal spreads in the circumferential direction, and the amount of spread depends on the defect length, depth, and width. Let's look more carefully at the effects of width for short, deep defects. The following buttons show how the signal changes with width.

The amplitude doubles over a range of widths from 1 to 3 inches and the signal width changes significantly.

A common method of estimating width is to use a threshold on signal amplitude. Estimating width using the number of sensors with amplitude above 150 gauss (shown in orange) gives a width of 1.5 for the 1 inche defect, 4 inches for the 2 inch defect, and 5 inches for the 3 inch defect. Other amplitudes produce similarly poor results.