Effect of GFRP spacer on local deformation of large superconductor in coil pack

Local deformation in a large superconductor caused by GFRP spacers and epoxy adhesives was investigated after compressive rigidity testing. The epoxy adhesive used for attaching the GFRP spacers to the superconductor changes shape from an almost square sheet into a lens-like sheet during deformation, and a dent appeared on the surface of the superconductor. Three-dimensional FEM analysis showed that a compressive stress in the vertical direction of the loading axis existed in the adhesive plane. This stress component makes the adhesive lens-like and it results in the dent created during the compressive testing. This local deformation should yield a part of the permanent deformation observed after the compressive load cycle at 4.2 K.<>