Analysis of the inducing frequency of a U-shaped ACFM system

According to the principle of the alternating current field measurement (ACFM), the inducing frequency has a significant influence on the signal acquisition and the measurement accuracy of an ACFM system. To design an ACFM prototype system with a U-shaped probe, the inducing frequency of the ACFM system is determined through simulation analysis and an experimental study in this paper. A large number of simulations are designed and run to analyze the influences of the inducing frequency on characteristic vectors of the induction electromagnetic field. By analyzing the simulation results, 6 kHz is selected to be the optimal inducing frequency for the U-shaped probe of an ACFM prototype. This frequency is tested by real crack inspection experiments using the U-shaped probe of the ACFM prototype in laboratory. The results show that 6 kHz is appropriate to realize the crack inspection and sizing with reasonable accuracy. The result in this paper will benefit the design and manufacturing of the prototype for the U-shaped probe ACFM system.