Experimental study on rebar stress measurement based on force-magnetic coupling under excited magnetic field

This paper used weak magnetic detection technology for nondestructive testing of rebar stresses. An applied excitation magnetic field was used to reduce the effect of different initial residual states of the rebar and to strengthen the force-magnetic coupling effect of the static tension process. Five sets of rebar samples were prepared, and magnetic field excitation with different magnitudes was applied. The tangential component of magnetic induction By is analyzed and the 'magnetic signal curve fluctuation parameter' A(W) is introduced. The results showed that the consistent variation pattern A(W)-T curves indicated magnetic field excitation could reduce the magnetic differences in various rebars tensile processes. When the excitation magnetic field strength exceeds the geomagnetic field, the A(W)-T curve in the elastic phase decreases linearly. By extracting the magnetic signals, the stress state in the elastic phase of the rebar is calculated by substituting for the formula, and the control error is within 15%.