Establishment of 3D multistage models of superconducting cable based on discrete element method

In this paper, in view of the discrete and multiscale characteristics of the cable-in-conduit conductors, a new bottom-up methodology for constructing a 3D model of multistage superconducting cable is proposed based on the discrete element method (DEM). On the basis of the discretization of the continuum and the improved cohesive bond model, a single-strand DEM model is first established. Furthermore, the spatially geometric configuration of the cable is generated stage by stage according to cylindrical spiral equations, and the contact force law is also introduced into the DEM model to characterize the interaction between the strands inside the cable. The established models are validated by means of macroscopic deformations of multistage cable under various external loadings. Under high transverse stress level, an elastic–plastic force law is tentatively introduced for characterizing plastic deformation of the strands at the contacts. Finally, the necessity of the incorporation of elastic–plastic force law into our DEM model of superconducting cable is further discussed. The proposed methodology presents a new way of constructing a multistage model from at strand even up to the full cable, and an additional potential advantage of the established model is to quantitatively investigate localized strains and nonuniform contacts inside the cable on a sub-cable level or even down to the level of a single strand. (paper)