Mechanical Calculations of a 2D Axisymmetric Pancake Model With Screening Current Distribution and Layers Contact Resolution With Pre-Tension

This article present the development of a finite element code to solve the mechanical behaviour of high field insert coils. The code uses a 2D axisymmetric model of high temperature superconducting (HTS) pancakes considering metal as insulation winding (MI) with over-banding turns. Based on a novel dynamic mesh model dedicated to pre-tensioned windings, the numerical calculation aims to solve stresses and strains distribution within the whole pancake including its mandrel, the winding, made of a ReBCO tape and a stainless steel tape, and some turns of over-banding, made of stainless steel tapes. We consider the pancake, as part of a double-pancakes stacked coil, subjected to three mechanical loadings, pre-tension during the winding process, cooling of the coil from room temperature to cryogenic temperature, energizing of the coil under external low temperature superconducting coil (LTS) external magnetic field. The calculations, include screening current distribution and loss of contact analysis. Stress and strain results issued from finite element method (FEM) analysis are benchmarked against two analytical formulations specially developed for MI orthotropic and pre-tensioned windings.