Numerical Simulation of Electromagnetic and Thermal Stress in REBaCuO Superconducting Ring and Disk Bulks Reinforced by Stainless Steel Ring With Various Widths During Field-Cooled Magnetization

The mechanical stress of the electromagnetic hoop stress, σ_θ^FCM, during field-cooled magnetization (FCM) from 20 T, and the thermal hoop stress, σ_θ^cool, under cooling, in REBaCuO disk and ring bulks reinforced by stainless steel (SUS) ring with various widths, were calculated using numerical simulations. The reinforcement effect of the SUS ring was investigated for each bulk. For the ring bulk, the maximum of σ_θ^FCM was reduced with increasing SUS ring width, from 216 MPa for without SUS ring reinforcement, down to 93 MPa for using SUS ring with 20 mm in width, was less than that of the disk bulk. The numerical results showed that the stress concentration in the ring bulk could be alleviated by the SUS ring reinforcement. We suggest that the width of SUS ring needs to be at least 10 mm to prevent the fracture behavior of the bulk. The optimal design of the reinforcement ring should be constructed so that the total hoop stress, σ_θ^total (= σ_θ^FCM + σ_θ^cool), could be less than the fracture strength of the bulk during FCM.