Stress analysis in high-temperature superconductors under pulsed field magnetization

Abstract

Bulk high-temperature superconductors (HTSs) have a high critical current density and can trap a large magnetic field. When bulk superconductors are magnetized by the pulsed field magnetization (PFM) technique, they are also subjected to a large electromagnetic stress, and the resulting thermal stress may cause cracking of the superconductor due to the brittle nature of the sample. In this paper, based on the H-formulation and the law of heat transfer, we can obtain the distributions of electromagnetic field and temperature, which are in qualitative agreement with experiment. After that, based on the dynamic equilibrium equations, the mechanical response of the bulk superconductor is determined. During the PFM process, the change in temperature has a dramatic effect on the radial and hoop stresses, and the maximum radial and hoop stress are 24.2 MPa and 22.6 MPa, respectively. The mechanical responses of a superconductor for different cases are also studied, such as the peak value of the applied field and the size of bulk superconductors. Finally, the stresses are also presented for different magnetization methods.

R-z plane spatial critical current inhomogeneity-induced mechanical response of GdBCO superconducting bulks during field cooling magnetization

“…The electromagnetic-thermal field and mechanical model are coupled through Lorentz forces f = J × B. The GdBCO sample is simplified as an isotropic and linear elastic material [45]. Due to the slow demagnetization process of FCM, the structural transient behavior of bulk is assumed to be quasi-static [9].…”

AC Loss and Magnetostriction of Anisotropic High-Temperature Superconductors Under Electro-Magnetic-Thermal Coupling Effect

“…The relationship between the electric field and the current density is given by the power law model [21,22]: where s (B, J, T) is the equivalent resistivity of the bulk superconductor and E c is the characteristic electric field and n = U 0 kT represents the chance of creep occurrence.…”

“…The external magnetic field applied to the superconducting sample is parallel to the z-axis direction of the specimen. The numerical model used in this paper is based on the two-dimensional H formula of the BiSr 2 CaCu 2 O 8+δ superconductor, which was implemented with the commercial finite element software COMSOL Multiphysics [34][35][36], and the parameters are shown in Table 1.…”

Numerical modelling and simulations on the mechanical failure of bulk superconductors during magnetization: based on the phase-field method

“…Research group lead by Zhou has made significant contributions to modeling the mechanical behaviors of bulk superconductors, and has systematically investigated the flux-pinning-induced magnetostriction [28], singular stress field and current density distribution in front of cracks within bulk superconductors [29,30]. Recently, Wu et al [31] numerically simulated the trapped field and stress distributions in bulk superconductors during pulsed field magnetization by solving the coupled H-formulation for electromagnetics, mechanical equilibrium equations and heat diffusion equations. Chen et al [32] studied the fracture behavior of the GdBCO bulk superconductor under large electromagnetic forces based on the Extended Finite Element Method (XFEM).…”