An Internal Stress Detection Technology of Concrete Based on Displacement Current.

Existing testing methods inadequately capture the internal stress state of concrete, a vital structural safety metric, resulting in a divergence between measured and actual internal stress states, especially in larger structures. There is an urgent need for innovative theoretical and technical approaches that can directly, accurately, and instantly reflect the internal stress state of concrete, meeting the growing demand for such detection. This paper conducts experimental research on the internal stress detection of concrete based on the principle of displacement current. Firstly, the theoretical relationship between the internal stress and oscillation frequency of concrete is established. Secondly, two dielectric plates are embedded in the concrete specimen as a sensing unit, and an LC oscillation circuit is connected externally to express the internal stress state of the concrete in the form of oscillation frequency. The research findings suggest that there is a decrease in the oscillation frequency as the dielectric constant of the concrete increases. Additionally, a significant change in the oscillation frequency is observed because of the dielectric polarization effect that takes place during the pouring and curing of the concrete specimen. The concrete age starts from about 25 days, and its oscillation frequency gradually stabilizes; the internal stress of the concrete is proportional to the oscillation frequency, and they show a good correlation in the experiment. [ABSTRACT FROM AUTHOR]