The position dependence of fracture behavior in a superconductor/ferromagnetic bilayer strip
The position dependence of fracture behavior in a superconductor/ferromagnetic bilayer strip
复制标题
超导/铁磁双层带中断裂行为的位置依赖性
DOI：
10.1016/j.mechrescom.2018.05.003
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发表时间：
2018
影响因子：
2.4
通讯作者：
Zhou Youhe
中科院分区：
文献类型：
--
作者：
He An;Xue Cun;Zhou Youhe
用有限元方法研究了裂纹位置和长度对超导/铁磁(SC/FM)双层带材断裂行为的影响。由于Sc/Fm杂化材料的复合结构，在磁化过程中，作用在Sc/Fm双层带材上的电磁体力会导致复杂的机械变形。当裂纹接近试件底部时，即使是在场上升阶段，裂纹也容易扩展，这与单一SC试件的特征有很大不同。此外，裂纹长度和位置导致应力强度因子(SIF)有两个反向变化。当裂纹接近超导层时，SIF为正值，且在磁场降低的中间阶段有峰值。相比之下，除中间阶段外，SIF均为正值，且在下降阶段开始时有最大值。应力强度因子与外加电场的这种新行为可以用不同裂纹位置沿厚度方向的应变分布来解释。一般情况下，最大外加电场时的最大应力强度因子远大于场下降阶段的最大应力强度因子。上、下尖端的断裂行为呈现出明显不同的特征。当裂纹足够靠近底面时，下尖端的最大应力强度因子比上尖端的大得多。
The effect of crack position and length on the fracture behavior in the superconductor/ferromagnetic (SC/FM) bilayer strip is investigated with finite element method. Owing to the composite structure of the SC/FM hybrids, the electromagnetic body force acting on the SC/FM bilayer strip will lead to complicated mechanical deformation during magnetization. The crack is prone to propagate even in the field ascent stage when the crack gets close to the sample bottom, which is quite different from the feature in a single SC sample. Moreover, the crack length and position leads to two inverse variations of stress intensity factor (SIF). SIF is positive and has peak value in the intermediate stage of field reduction when crack is close to superconducting layer. By contrast, SIF is positive except the intermediate stage and has maximum value at the beginning of the descent stage. Such novel behavior of SIF versus applied field can be explained by the strain distribution along the thickness direction for various crack positions. Generally, the maximum SIF at the maximum applied field is much larger than that in the field descent stage. The fracture behavior at the upper tip and lower tip exhibits significantly different characteristics. The maximum SIF at the lower tip is much larger than that at the upper tip as the crack is sufficiently close to the bottom surface.