Abstract Modern superconducting intermetallic materials (e.g. NbTi, Nb3Sn) are used to build conductors composed of a matrix and the superconductor strands. One of the most popular materials for matrix is copper, because of its excellent physical and mechanical properties at extremely low temperatures. Ductile OFE copper stabilizes, on one hand, the mechanical response of brittle superconductor strands and, on the other hand, takes over the electrical charge in case of quench (resistive transition). Thus, the composite structure of modern conductors used to build the coils of superconducting magnets is fully justified. Such a composite structure results in common deformation of the matrix and the strands when winding the coils and during the operation, when the coils are subjected to the prestress and to the Lorentz forces at extremely low temperatures (liquid or superfluid helium). When the loads are large enough, the copper-superconductor strands composite is subjected to inelastic deformation, including moderately large plastic strains. It is known, that copper and superconductor strands exhibit the so-called discontinuous plastic flow (DPF) at extremely low temperatures, that results in abrupt drops of stress against strain of different amplitude and frequency. In order to describe correctly the behaviour of composite superconductors at extremely low temperatures, a constitutive model of DPF has been developed and applied to both components: matrix and strands. The results of numerical analysis are compared with the experiments, carried out in dedicated cryostat containing liquid helium and the relevant instruments.

中文翻译：

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超导复丝复合材料中的不连续塑性流动

摘要 现代超导金属间材料（如NbTi、Nb3Sn）用于构建由基体和超导体股线组成的导体。最流行的基体材料之一是铜，因为它在极低的温度下具有出色的物理和机械性能。延展性 OFE 铜一方面稳定脆性超导体股线的机械响应，另一方面在失超（电阻转变）的情况下接管电荷。因此，用于构建超导磁体线圈的现代导体的复合结构是完全合理的。这种复合结构导致在缠绕线圈时和操作过程中基体和股线的共同变形，当线圈在极低温度（液态或超流氦）下承受预应力和洛伦兹力时。当载荷足够大时，铜-超导体股线复合材料会发生非弹性变形，包括适度大的塑性应变。众所周知，铜和超导体股线在极低的温度下表现出所谓的不连续塑性流动 (DPF)，这会导致应力突然下降，以应对不同幅度和频率的应变。为了正确描述复合超导体在极低温度下的行为，开发了 DPF 本构模型并将其应用于两个组件：基体和股线。数值分析结果与实验对比，