Magnetic flux leakage structural health monitoring of concrete rebar using an open electromagnetic excitation technique

The current methods of electric–magnetic flux leakage structural health monitoring that use tubular coils as electro-magnetizers fail to detect concrete rebar structures without a head and a tail. This article proposes a novel electric–magnetic flux leakage structural health monitoring technique for concrete rebar using open electromagnetic coils as magnetizers. Three-dimensional finite element simulations and experiments are conducted to compare the magnetization effect, defect-detection capability, and magnetic force interaction of traditional tubular coils and the proposed open electromagnetic coils. The agreement between the simulation and experimental results confirms the reliability and validity of the proposed structural health monitoring technique for concrete rebar. Additionally, two types of magnetizer coils are designed and manufactured using optimized structures, and both limitations and solutions are discussed. Overall, the proposed open magnetizer coils show great potential for future structural health monitoring applications for concrete rebar.