Material optimization of ferromagnetic shields

This work reports the optimized design of a ferromagnetic shield for a 200-kJ superconducting magnetic energy storage (SMES) system under construction at the University of Bologna. Low weight and cost of the shield and a low stray field in the neighborhood of the device are required. In order to meet the design requirements a multiobjective minimization problem is solved. The main feature of the design procedure proposed is the direct introduction of the shield material as an optimization variable. This allows one to choose the cheapest and lightest material for the shield, together with the position and dimensions of the shield itself. The model for the analysis of the magnetic induction field is based on the boundary-element technique. The results obtained have been verified with a multidimensional finite-element-based analysis method.