Fatigue damage detection and location of metal materials by electrical impedance tomography

Abstract Electrical impedance tomography (EIT) technology is widely used in the field of biomedical research. Its basic principle is to use the material's own impedance characteristics to characterize its internal structure. The study found that the damage process of metal materials is accompanied by the change in impedance distribution. Aiming at damage detection and damage location of metal materials, a micro-resistance detection technique suitable for damage in metal materials is proposed. The imaging of damage in metal materials was analyzed by the typical dynamic imaging algorithm in EIT technology which is the equipotential lines back-projection algorithm. In this paper, the four-terminal method of DC Kelvin double-arm Bridge was used to measure the micro-resistance of 45# steel specimens with damage. According to the rate of resistance change between electrodes before and after damage, the images of the specimens were reconstructed by the equipotential lines back-projection algorithm, which could identify the location of damage.