Deformation analysis of pulsed magnets with internal and external reinforcement

Abstract

Stresses and strains in the mid-plane of a pulsed magnet are analytically calculated by solving the system of equations describing the displacement in each layer of the coil. Nonlinear stress-strain characteristics and the propagation of plastic deformation are taken into account by sub-dividing each layer of the coil in the radial direction and changing the elastic-plastic matrix at each transition point. The effects of pre-stressing during winding and thermal stresses are calculated and discussed. Two coils that have been tested up to 60-70 T fields are described as examples. It is shown that, under some conditions, elastic-plastic cycling leads to a stable state, whereas in others this results in runaway deformation that leads to coil destruction after a few cycles.