METHOD OF DETERMINATION OF MECHANICAL STRESSES AND DEVICE FOR REALIZATION OF THIS METHOD Russian patent published in 2002 - IPC

FIELD: nondestructive testing; determination of mechanical stresses in ferromagnetic articles. SUBSTANCE: directed magnetic flux of definite magnitude is excited in metal of article under test and turning cruciform magnetic circuit 7 around axis perpendicular to plane of its poles and position of magnetic circuit corresponding to maximum magnitude of emf U_x1, induced in measuring winding 8 is found and fixed. Magnitude U_x1 is read off for calculations. Ambiguity of dependence of emf in measuring winding 8 on magnitude of mechanical load metal is taken into account. To this end, another definite magnitude of magnetic flux is set by changing the magnetizing current by means of amplifier 3 and new magnitude of emf U_x2. is read off. Mechanical stress is determined with the use of emf's read off in the course of measurement at indicated magnitudes of magnetic flux. Possibility of performing measurements in one point at two different modes of magnetizing is ensured due to introduction of the following components into the device, viz. : clock pulse generator 1, loop selection flip-flop 2, magnetizing current amplifier 3, switches 12 and 13, analog-to-digital converter 21, triggering pulse shaper 22 at definite relation and connection with other units of device. Proposed device ensures storage of interpretation of results for each hysteresis loop and automatic logic analysis of selection of most probable result of measurement due to availability of on-line storage 17, processing control flip-flop 23, function generators 25, 26, 27 and 28, bias generator 29, logic comparison unit 30. Output code of unit 30 on display of indictor 24 corresponds to readings in units of measurement of mechanical stresses. EFFECT: enhanced accuracy of measurement. 3 cl, 2 dwg