ABSTRACT: The large range of length scales presents within superconducting magnet and its heterogeneity, a straightforward numerical simulation of a magnet, considering all details of the microstructures would cost enormous time, so incorporation of the multiscale approaches into computational models can facilitate the numerical analysis. Additionally, the superconducting magnet with high transport current and intense magnetic field are often exposed to large Lorentz forces, which lead to the unavoidable deformation in superconducting coils, the deformation will further disturb the quality of the magnetic field. In this work, the stress/strain and magnetic field of a 4T NbTi/Cu racetrack superconducting magnet were numerical analyzed, a multiscale model from the NbTi filament scale to the coil scale was developed to obtain the homogenized and the orthotropic material properties of the superconducting coil based on the representative volume element (RVE) and rule of mixture of composite methods, these material properties are employed to solve for stress/strain and magnetic field development by using three-dimensional finite element method (FEM), and taking into account the effect from magneto-mechanical coupling of superconducting coils. The study shows that the numerical predictions based on multiscale approach for the superconducting coils on the strain are in better agreement with the previous experimental data than those based on a single-scale approach, and shows the magneto-mechanical coupling behavior of the superconducting coils is remarkable especially in intense magnetic field and large transport current. The FEM based on multiscale model was demonstrated as an acceptable method to estimate the required material properties of the superconducting coils for the magneto-mechanical analysis of a superconducting magnet.
Key words: multiscale model, magneto-mechanical coupling, FEM, superconducting magnet.