Method
The ACFM probe induces a uniform alternating current in the area under test and detects magnetic field of the resulting current near the surface.
This current is undisturbed if the area is defect free. A crack redirects the current around the ends and faces of the crack. The ACFM instrument measures these disturbances in the field and uses mathematical modelling to estimate crack size. The lateral and vertical components of the magnetic field are analyzed; disturbances indicate a crack is present, and the size and depth of the crack can be calculated.
Read more about this topic: Alternating Current Field Measurement
Famous quotes containing the word method:
“Women are denied masturbation even more severely than men and thats another method of controltheyre not taught to please themselves.... Most womenit takes them a while to warm up to the situation but once they get into it, Im sure theyre going to get just as hooked aswell, everyone I know is!”
—Lydia Lunch (b. 1959)
“Letters are above all useful as a means of expressing the ideal self; and no other method of communication is quite so good for this purpose.... In letters we can reform without practice, beg without humiliation, snip and shape embarrassing experiences to the measure of our own desires....”
—Elizabeth Hardwick (b. 1916)
“Protestantism has the method of Jesus with His secret too much left out of mind; Catholicism has His secret with His method too much left out of mind; neither has His unerring balance, His intuition, His sweet reasonableness. But both have hold of a great truth, and get from it a great power.”
—Matthew Arnold (18221888)