电磁热耦合作用下缺陷超导体的力学行为研究

Study on mechanical behavior of defect superconductor under electromagnetic thermal coupling

超导体在制备和降温时会出现孔洞缺陷或裂纹,从而影响超导体的安全可靠性与力学稳定性。基于H法有限元模型求解了带有椭圆孔缺陷的圆柱状超导体在电磁热耦合作用下的力学行为。研究表明,电磁体力在缺陷尖端出现局部增强,在缺陷非尖端附近出现拉压共存,主要是因为缺陷影响了感应电流的分布;相比于圆孔缺陷的应力集中情况,椭圆孔缺陷处的径向应力和环向应力都有非常显著的集中现象,且其缺陷附近的环向应力曲线更为陡峭;椭圆孔长轴增大或短轴减小时,径向应力峰值和环向应力峰值均显著增大;对超导体采用不锈钢加固环可有效抑制应力的增大,从而可保证超导体正常运行。

Holes or cracks will appear in superconductors during preparation and cooling,which will affect their safety and mechanical stability.In this paper,the mechanical behavior of cylindrical superconductors with elliptical hole defects under electromagnetic-thermal coupling was solved based on H-method finite element model.The results show that the electromagnetic force increases locally at the tip of the defect and coexists in tension and compression near the non-tip,which is mainly due to the influence of the defect on the distribution of induced current.Compared with the stress distribution at the circular hole defect,the radial stress and circumferential stress at the elliptical hole defect have a very significant concentration phenomenon,and the circumferential stress curve is steeper than the radial stress near the defect.When the length of long axis of elliptical hole is increased or the short axis is decreased,the peak value of radial stress and the peak value of circumferential stress increase significantly.Adopting stainless steel reinforcing rings to superconductors can effectively restrain the increase of stress,thus ensuring the normal operation of superconductors.