Some considerations on the stress analysis of the Swiss coil for the large coil task

A finite element stress analysis of the coil under consideration is unavoidable due to the proximity of the stresses to the 0.2% yield strength. The casing of this D-shaped coil is both a hollow body and a looped one. This leads to computing costs and memory requirements which are enormous and preclude any parametric study. To reduce computer costs a newly developed code, FLASH, has been used. It has a hybrid stress model leading to more rapid convergence and thick plate elements which allow bending moments to be computed. Only one thick plate is needed across the thickness of the casing and local stress concentrations are obtained from the mean stress and the bending moment. Several models were developed most of which can be set up automatically. Comparisons between the models and with ASKA finite element results from BROWN BOVERI Co. essentially show agreement. Parametric variations were done to study the effects of boundary conditions. The casing of individual conductors has also been investigated with the same code. Both the effect of the Lorentz forces and those arising from the quench pressure due to helium heating on loss of superconductivity have been considered. (author)