Finite element investigation of the mechanical behaviour of a Twisted Stacked-Tape Cable exposed to large Lorentz loads

Abstract

The mechanical response of Twisted Stacked-Tape Cables (TSTC) experiencing large Lorentz loads generated during its operation in high-current, high-field magnets was investigated using finite element analysis. Two conductor configurations were investigated: a stack of 40 REBCO tapes inside a solid cylindrical copper rod (former) and a solder filled copper tube. Several simulations were conducted to highlight the effect of different parameters in the cable and the differences between the two configurations. A parametric study on the geometrical parameters of the solder filled tube configuration was performed. It was found that increasing the ratio between the thickness of the copper tube and the amount of solder in the cross section lowers the maximum stress experienced by the stack of tapes. Another simulation explored the effect of using different width tapes in the stack and it was found that, for a given Lorentz load, a wider tape reduces the maximum stress experienced by the stack. In certain applications, the cable requires the addition of material for structural support or stability reasons therefore a simulation was performed to understand the effect of copper surroundings. It was found that surrounding the cable with copper as well as using a thick copper tube lowers the stress experienced by the stack and makes the behaviour of the copper core and the solder filled tube configurations almost identical. Finally, the critical current performance of the TSTC conductors as a function of Lorentz load was estimated. A minimal degradation below 2% was predicted for the copper core configuration up to 1000 kN/m and up to 600 kN/m for the solder filled tube configuration.