Peter H. Titus
Stone & Webster Engineering Corporation, under contract to MIT Plasma Science and Fusion Center, Cambridge MA
Anatoly Panin
D. V. Efremov Institute, St. Petersburg, Russia
Alexey I. Borovkov
St. Petrersburg State Techincal University , Russia
The structural integrity of the CS relies on the insulation system to bind the conductor jackets into a monolithic media that is capable of accepting the radially inward loads from the bucked TF and the self loads from the CS. The CS must also accommodate the flexural motions of the TF case. Shear stresses in the CS are computed in a large ANSYS global model of the magnet system. The local structural response of the jacket also adds shear stresses at the bonds between neighboring conductors, particularly where neighboring sidewalls attempt to act together as a composite beams bonded at their neutral axis. Each of the six stress components of the "smeared" CS stress state from the global model induces additional local shears and normal stresses within the insulation between conductors. The full inventory of multipliers have been computed with detailed local models of the array of conductors with unit loads or displacements applied. These multipliers are applied in post processing of the global model results. For this study, aligned and misaligned conductor winding arrangements have been considered. The acceptance criteria for insulation shear stress is expressed as an allowable shear equal to normal compression multiplied by a shear/compression augmentation factor plus bond strength in the absence of compression. At each point on the face, there are 3 insulation stress components of interest. These result from concern over the integrity of inter-laminar stresses. At each of 20 points around the perimeter of the jacket, for the misaligned and aligned configurations of conductor, two surface shears and one surface normal are computed from the global model stress components, and the multipliers computed from unit cell local models of the conductor jacket and insulation system. The vector sum of the two surface shears is subtracted from the normal stress multiplied by C2, the shear-compression augmentation factor. This is the required bond strength and is compared with the allowable bond strength. Contour plots of required bond strength are presented. R value effects are discussed. Results for the baseline configuration of the ITER magnet are included along with results for alternate concepts.