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

FIELD: nondestructive material testing; determination of mechanical stresses in articles made from ferromagnetic materials. SUBSTANCE: directed magnetic flux of definite magnitude and frequency is excited in metal of article under test in preset directions at pitch β not exceeding 45 deg. within 0 to (±180^°-β), changing-over excitation windings in turn which are located on arms of cruciform magnetic circuit of converter. Every time emf U_x1, induced in measuring windings located on arms of magnetic circuit perpendicular to arms of magnetic circuit with excitation windings is measured. Similar measurements are repeated for other magnitude of magnetic flux. Angular dependence of emf U_x1 for each of preset directions of magnetizing and for each level of magnetic flux is approximated and magnitudes for further processing are taken by approximated dependences. Mechanical stress σ is determined using emf approximated by functions such as σ = A^•tg(KU_x)±Δ,, where A, K and Δ are graduated constants. Stresses in preset layer are estimated through similar measurements at other frequencies. Possibility of performing measurements at each point of test at different modes of magnetizing is ensured due to introduction of power amplifier, two digital-to-analog converters, switchgear, analog-to-digital converter, microprocessor and on-line storage, as well as their relation and connection with other units. EFFECT: enhanced accuracy; extended field of application. 5 cl, 4 dwg