高温超导带材超导涂层局部脱黏后的电磁力学行为分析
ELECTROMAGNETIC MECHANICAL BEHAVIOR OF A SUPERCONDUCTING COATING FOR HTS TAPES WITH LOCAL DETACHMENT
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摘要: 高温超导带材因其高载流z能力、低交流损耗等优点, 在超导领域得到了广泛的关注, 然而在带材的应用中出现的力学问题严重阻碍了其应用. 基于此, 本文分析了受外部磁场激励YBCO高温超导带材在超导层局部脱黏后的电磁力学响应. 基于超导临界态Bean模型和弹性力学平面应变方法, 给出了超导薄膜内正应力与基底界面处切应力相关联的控制方程, 基于数值方法研究了超导薄膜内的正应力及基底界面处的切应力随外部磁场的变化规律. 结果显示: 在脱黏区域附近, 超导薄膜内的正应力和基底\!-\!薄膜界面处的切应力急剧增大, 该正应力及切应力极易引起超导层的进一步脱黏. 同时, 剪切应力在结构边缘处出现极值. 基底材料的属性, 特别是杨氏模量对结构内的应力影响显著, 在软基底材料结构中, 超导薄膜内将出现较大的正应力, 而基底材料较硬时, 在基底\!-\!薄膜界面处将出现较大的剪切应力, 这些因素均会引起超导涂层结构的力学及电学性能的退化. 本文研究可望为超导带材的加工制备及脱黏的处理提供一定的理论指引.Abstract: High temperature superconducting tapes has been widely investigated in the field of superconducting technology due to its outstanding advantages of high current carrying, low loss and high cost performance. However, the superconducting tape is a multi-layer structure consisting of the Hastelloy alloy substrate, the buffer layer, the YBCO superconducting layer and the protective layer. Its multi-layer structure characteristics including the difference in the properties of each material layer and the complex external field environment will cause local debonding. It is very easy to degrade the transmission performance and mechanical properties. In this paper, the mechanical response of locally detachment YBCO high-temperature superconducting tapes under the excitation of an external vertical magnetic field is studied. Based on the superconducting critical state Bean model and the elasticity plane strain method, the interface between the normal stress of the superconducting film and the substrate is given. The governing equations related to the shear stress, numerically calculated the normal stress in the superconducting film and the shear stress at the substrate interface with the external magnetic field. The results show that the normal stress in the superconducting film and the shear stress at the substrate film interface increase rapidly near the detachment region. At the same time, the maximum shear stress appears at the edge of the structure. The properties of the substrate material, especially the Young's modulus, has a significant effect on the stress in the structure. In the structure of soft substrate material, there is a large normal stress in the superconducting film, and when the Young's modulus of the substrate is larger, a larger shear stress appears at the substrate film interface. These factors will cause the degradation of mechanical and electrical properties of superconducting coating structure. The work may provide some theoretical guidance for fabricating the superconducting tapes and and suppression of layer debonding.