Recent development of alternating current field measurement technology for defects detection: A review

Alternating current field measurement (ACFM) technology is a promising nondestructive testing (NDT) method with the advantages of non-contact capability, robustness to lift-off effects and quantitative detection. Recently, new theories, models, sensors and methods are introduced in the ACFM technique which improves the defect detection capability and expands the application scope. This paper presents a review of the state-of-the-art in ACFM technology and discusses future development directions. The paper aims to provide a roadmap for future research and development in the ACFM field. In the basic theory, the ACFM signal forward and the defect inverse problems have been studied by many researchers using new methods and techniques. New excitation modes and detection sensors have been developed to extend the scope of ACFM technology. With the growing demand for specialized detections and evaluation requirements, the ACFM technology has been increasingly applied in offshore, nuclear power, rail transport, and special equipment fields. The critical challenges and areas for further research are discussed in the paper. Based on the literature review and current industrial needs, it is evident that ACFM has entered a stage of rapid and mature development. Additionally, ACFM has given rise to several novel branches in conjunction with other technologies.