金属套筒对圆柱超导体内裂纹强度因子的影响研究

Effect of metal sleeve on crack strength factor of cylinder superconductor

建立了一个外部包裹厚度为d的金属套筒且含有中心裂纹的YBCO圆柱型超导体模型,将其置于变化的外磁场环境中。采用Kim模型,通过ABAQUS软件有限元法和J积分法,忽略金属套筒对超导体磁场捕获能力的影响,对圆柱超导体内裂纹尖端应力强度因子的变化规律进行了数值仿真研究。数值结果表明,金属套筒弹性模量、金属套筒厚度和裂纹长度对圆柱超导体内裂纹的应力强度因子有显著的影响。超导体内合力为拉力时,金属套筒抑制裂纹扩张;当金属套筒与超导体弹性模量之比大于2时,抑制作用变化不明显,强度因子相应减小;裂纹尖端受到相同拉应力时,有金属套筒的裂纹长度是无金属套筒裂纹长度的1.1倍。

In this paper,a YBCO cylindrical superconductor with a central crack is set up,which wrap a metal sleeve with thickness d.In the external magnetic field,the superconductor cylinder will be subjected to electromagnetic force during the change of the external magnetic field.The change of stress intensity factor at crack tip is solved by finite element method,and the influence of metal sleeve on magnetic field trapping ability of superconductor is ignored in the whole process.The numerical results show that the external magnetic field,the elastic modulus of the metal sleeve,the thickness of the metal sleeve and the crack length has obvious effects on the crack stress intensity factor growth of the cylindrical superconductor.When the tensile force is reasonable in the superconductor,the metal sleeve plays a significantly inhibitory role on the crack growth,but when the ratio of the Em/Es is greater than 2,the inhibitory effect is not obvious.In addition,the crack tip receives the same tensile stress,the crack length with metal sleeve is 1.1 times than that without metal sleeve.