UNIVERSAL CONTROL SAMPLE FOR FAULT DETECTION Russian patent published in 2006 - IPC G01N27/82 

FIELD: the invention refers to the field of nondestructive control.

SUBSTANCE: the sample has a plate with an opening and a bushing of the same material installed in it. The opening and the bushing are fulfilled in a stepped form in the shape of several coaxial cylinders with diameters d₁ , d₂ ...d_n decreasing in accord with the depth of the plate and fulfilled on the depth t_1, t_{2 ...}t_n correspondingly from the surface of the sample. The conjugation of steps forms subsurface defects. The sample may be fulfilled of ferromagnetic material or of nonmagnetic material conducting electricity.

EFFECT: allows to control defects.

2 cl, 3 dwg