Insulation interlaminar shear strength testing with compression and irradiation

The Compact Ignition Tokamak (CIT) project identified the need for research and development for the insulation to be used in the toroidal field coils. The requirements included tolerance to a combination of high compression (380 MPa) and shear (93-MPa shear stress) and a high radiation does (approximately 10¹⁰ rad). The materials included various combinations of epoxy, polyimide, E-glass, S-glass, and T-glass in the form of a three-dimensional (3-D) weave. The data before irradiation for smaller sample configurations developed for irradiation tests were similar to those for the larger samples, but approximately 10% lower. Limited fatigue testing was also performed by cycling the shear load. No reduction in shear strength was found after 50000 cycles at 90% of the failure stress. Because of space limitations, only three materials were chosen for irradiation: two polyimide systems and one epoxy system. The shear strength with compression before and after irradiation at the lower dose was determined