考虑磁通流动效应的超导薄膜基底结构界面断裂行为研究

A Study on Interfacial Fracture Behaviors of Superconducting Thin Film/Substrate Structures on Taking the Account of Effects of Flux Flow

超导薄膜是一种采用化学涂层制备而成的多层薄膜结构,作为性能优越的导电功能结构材料,其载流能力与结构完整性直接相关.在超导薄膜制备过程中,超导层与金属基底之间的界面裂纹很难避免.因此,在载流运行过程中,由于外磁场的存在,这类界面裂纹的强度问题成为关键.为此,该文针对超导薄膜结构,以磁通量子穿透薄膜理论和线弹性断裂理论为基础,建立了研究超导层与基底界面裂纹强度问题的解析模型.深入分析了外加磁场作用下界面裂纹强度问题,得到了超导磁通流动对裂纹尖端应力场和能量释放率的影响.结果表明:磁通流动速度越大,界面裂纹尖端处应力越大且能量释放率越大,这将导致界面更容易发生裂纹破坏.该文所得结果有助于分析相关的界面裂纹问题.

The superconducting thin film is a kind of multilayer structure prepared by chemical coating. As a conductive functional structure material with excellent performance, its structural integrity is directly related to the current-carrying capacity. During the preparation of superconducting thin films, it is hard to avoid the interface cracks between the superconducting layer and the metal substrate. In this case, along with the current-carrying operation, the strength of the interface crack in an external magnetic field makes a key problem. Therefore, based on the theory of flux through the thin film and the linear elastic fracture, an analytical model was established for the strength of the interface crack between the superconducting film and the substrate. The effects of the viscous flux flow on the stress field and the energy release rate at the crack tip were obtained. The results show that, the higher the flux flow velocity is, the greater the stress and the energy release rate at the crack tip of the interface will be, which will lead to crack propagation along the interface. The work is helpful for the analysis of interface cracks mentioned above.