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:
“There is assuredly no more effectual method of clearing up one’s own mind on any subject than by talking it over, so to speak, with men of real power and grasp, who have considered it from a totally different point of view.”
—Thomas Henry Huxley (1825–95)
“A method of child-rearing is not—or should not be—a whim, a fashion or a shibboleth. It should derive from an understanding of the developing child, of his physical and mental equipment at any given stage, and, therefore, his readiness at any given stage to adapt, to learn, to regulate his behavior according to parental expectations.”
—Selma H. Fraiberg (20th century)
“If all feeling for grace and beauty were not extinguished in the mass of mankind at the actual moment, such a method of locomotion as cycling could never have found acceptance; no man or woman with the slightest aesthetic sense could assume the ludicrous position necessary for it.”
—Ouida [Marie Louise De La Ramée] (1839–1908)