Hybrid modeling method of shielding efficiency for rectangular magnetic shielding device with geometric discontinuity under different magnetization states

Stable weak magnetic field environment is a prerequisite for the high-precision performance of sensitive magnetic measurement instruments, and its stability is ensured by magnetic shielding devices (MSD). The optimized design of the MSD relies on the accurate modeling of shielding efficiency (SE), however, conventional analytical models struggle to address geometric discontinuity and the nonlinear permeability under varying magnetization states. To accurately calculate the SE under complex conditions, a hybrid modeling method for rectangular MSD with geometric discontinuity under different magnetization states is proposed in this paper. First, the effect of geometric discontinuity on the overall permeability is theoretically analyzed. Combining the B-H constitutive relationship, a finite element model is established, introducing an equivalent permeability correction method to compensate for numerical deviation caused by geometric discontinuity. Subsequently, splicing gaps and holes are incorporated to simulate the influence of geometric discontinuity and magnetization state on SE. Finally, experiments are conducted on a scaled-down MSD, where the normalized root mean square error between simulation and measurement data is less than 5.21%, validating the effectiveness of the proposed modeling method. An improved strategy for nanocrystalline alloy film coverage is also proposed, which increases the SE by 71.5 % on average.