Study on eddy current testing method of stress in load-bearing steel structure based on magnetoelastic effect

Abstract Aiming at the demand for accurate non-destructive testing and evaluation of stresses in large load-bearing steel structures, this paper proposes an eddy current testing method to assess stress without requiring an external magnetising device. Firstly, an eddy current detection model of steel plate stress is established based on the magnetoelastic effect, which theoretically explains the basic principle of stress eddy current detection of ferromagnetic materials. Secondly, the parameters of the excitation and detection coils and the effect of the excitation frequency on the detecting signal are studied. Finally, a system is built to carry out the experimental study of eddy current detection of steel plate stress. The experimental results show that: in the elastic stage, the detection signal has a good linear relationship with the steel plate stress, the detection sensitivity is about 0.25 mV/MPa; in the plastic stage, the detection signal increases and then decreases with the stress. The method proposed in the paper can accurately represent the stress distribution of steel plate specimens within a certain strain range.