Magnetic shielding of a thin Al/steel/Al composite

Purpose-This paper aims to investigate the efficiency of a laminated composite for shielding applications. The solution has to be efficient not only for the shield against static magnetic fields but also "for low-frequency ones, in order to be well-suited for applications with electromagnetic perturbations in the frequency range DC to 100 kHz." Design/methodology/approach-The composite constituted of a steel sheet taken in a sandwich between two aluminum (Al) sheets is produced by cold roll bonding. A good adherence between Al and steel sheets, ensuring a good mechanical resistance, is obtained with a specific process. A previous study has shown that the optimal trade-off between adherence and magnetic shielding effectiveness (SE H) is obtained with a 230 mm composite produced with an initial thickness of Al and steel sheets, respectively, of 250 and 100 mm. In this paper, the 230 mm Al/steel/Al composite is used in three applications modelized by two-dimensional numerical simulations. To obtain reasonable computation time for the simulations, a homogenization method is applied to the composite. Studied applications are a cylindrical box containing a coil, a square box under an external magnetic field and a high voltage cable. Findings-In each application, SE H is calculated at low frequency and different materials (Al/steel/Al, Al, steel and copper) are compared. It is observed that, in each application, the composite presents higher SE H at equal mass, especially for frequencies between 5 and 100 kHz. Originality/value-The proposed approach, from the material point of view to the system consideration, shows that the thin bimetallic composite is an innovative and promising solution for magnetic shielding in the case of applications with both DC and low-frequency perturbations.