Fracture analysis of a central crack in a long cylindrical superconductor with exponential model

2018 ◽  
Vol 32 (14) ◽  
pp. 1850145 ◽  
Author(s):  
Yu Feng Zhao ◽  
Chi Xu
Keyword(s):  
Fracture Behavior ◽  
High Temperature Superconductors ◽  
Crack Problem ◽  
Exponential Model ◽  
Zero Field ◽  
The Finite Element Method ◽  
Central Crack ◽  
Bulk Superconductors ◽  
Different Characteristics ◽  
Field Cooling

The fracture behavior of a long cylindrical superconductor is investigated by modeling a central crack that is induced by electromagnetic force. Based on the exponential model, the stress intensity factors (SIFs) with the dimensionless parameter p and the length of the crack a/R for the zero-field cooling (ZFC) and field-cooling (FC) processes are numerically simulated using the finite element method (FEM) and assuming a persistent current flow. As the applied field [Formula: see text] decreases, the dependence of p and a/R on the SIFs in the ZFC process is exactly opposite to that observed in the FC process. Numerical results indicate that the exponential model exhibits different characteristics for the trend of the SIFs from the results obtained using the Bean and Kim models. This implies that the crack length and the trapped field have significant effects on the fracture behavior of bulk superconductors. The obtained results are useful for understanding the critical-state model of high-temperature superconductors in crack problem.

Calculation of the Interaction Forces between Superconductor and Permanent Magnet Using Equivalent Current Loops in Zero Field Cooling

2013 ◽  
Vol 634-638 ◽  
pp. 2436-2441
Author(s):  
Yong Yang ◽  
Xiao Jing Zheng ◽  
Tao Li ◽  
Zhi Qiang Hua
Keyword(s):  
Permanent Magnets ◽  
High Temperature Superconductors ◽  
Magnetic Bearing ◽  
Image Method ◽  
Zero Field ◽  
Vertical Force ◽  
Interaction Forces ◽  
Magnetic Dipoles ◽  
Zero Field Cooling ◽  
Field Cooling

The levitation between high temperature superconductors (HTSs) and permanent magnets (PMs) has been applied to the flywheel energy storage systems and magnetic bearing systems for the last nearly twenty years. The interaction forces acting on the levitating body are calculated by the modified frozen-image method. The magnetic dipoles are equivalent to Amperian current loops. The current intensity in loops changes linearly when the PM moves. Under the zero field cooling condition, the expression of vertical force is obtained when the PM traverses vertically, and when the PM traverses horizontally, the expressions of vertical and horizontal forces are obtained. Those expressions of vertical and horizontal forces are gained by calculating the forces between current loops and using superposition theorem of vector. The calculations agree well with the previous experimental data, which means that the deductions of the expressions are reliable.

scholarly journals Attraction and repulsion forces in melt-textured and sintered YBCO-superconductors: a comparative study

2020 ◽  
pp. 44-50
Author(s):  
Diego Andrés Arias-Arana ◽  
Juan Diego Rojas-Zambrano ◽  
Álvaro Mariño-Camargo
Keyword(s):  
Low Cost ◽  
Sintered Sample ◽  
Interaction Force ◽  
Solid State Reaction Method ◽  
Zero Field ◽  
Bulk Superconductors ◽  
Ybco Superconductors ◽  
Growth Method ◽  
Magnetic Flux Pinning ◽  
Field Cooling

In this paper, we measure the attraction (suspension) and repulsion (levitation) forces produced by the interaction between a permanent magnet and different bulk superconductors. The measurements of the interaction force HTS-PM were carried out with a relatively simple technique developed by us, which is reproducible, reliable and low cost. The obtained results were analyzed with the Bean’s critical-state model assuming a uniform magnetic field applied to the superconductor. Two superconducting samples of YBa2Cu3O7-δ (YBCO) prepared by solid-state reaction method and by the melt-textured growth method (MTG) were used. Both samples presented a different hysteresis behaviour in the field cooling (FC) and zero field cooling (ZFC) regimes. Levitation and suspension phenomena were observed in the MTG sample; however, the sintered sample (S) with Oxygen deficiencies (δ > 0.15) displayed a slight levitation force but did not show a suspension force, the latter one attributed to a more efficient magnetic flux pinning. Additionally, the critical current density of both samples was determined from the maximum gap of the force (ΔF) in the FC regime. The obtained values were between 43.00 A/cm2 and 2,758 A/cm2 for the sintered and MTG samples, respectively. These values show a remarkable difference between sintered and MTG samples like that observed from magnetization measurements, which indicate that attraction and repulsion force measurements could provide a rapid and reliable characterization method of polycrystalline superconducting samples.  

FRACTURE BEHAVIOR FOR A LONG CENTER SLANT CRACKED RECTANGULAR SLAB OF SUPERCONDUCTOR UNDER ELECTROMAGNETIC FORCE

2009 ◽  
Vol 23 (06) ◽  
pp. 825-834 ◽  
Author(s):  
ZHI WEN GAO ◽  
YOU HE ZHOU
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Electromagnetic Force ◽  
Fracture Behavior ◽  
Numerical Results ◽  
Ybco Superconductor ◽  
Zero Field ◽  
Intensity Factors ◽  
Magnetization Processes ◽  
Field Cooling

This paper presents a theoretical analysis to the fracture behavior of the large single-domain YBCO superconductor with a center slant crack under electromagnetic force. The stress intensity factors are obtained by using the coupled finite element and infinite element numerical method. Numerical results are computed for two activation processes. For the zero-field cooling (ZFC) magnetization processes, the stress intensity factors increase as the applied field becomes large during field descent. For the field cooling (FC) magnetization processes, the stress intensity factors are obvious differences between the two cases when bfc > 1 and bfc ≤ 1. In addition, the predicted crack growth is the Mode-I fracture mainly. In this case, the numerical results developed in the present work are considered to be available for providing quantitative predictions of the fracture mechanism of superconductor both in theory and applications.

Magnetostriction-induced stress in an orthotropic mechanical thin high-temperature superconducting disk based on the exponential model of critical state

2021 ◽  
pp. 2150101
Author(s):  
K. F. Wang ◽  
B. L. Wang
Keyword(s):  
High Temperature ◽  
Critical State ◽  
High Strength ◽  
Approximate Solutions ◽  
Exponential Model ◽  
Zero Field ◽  
Reliability Design ◽  
High Temperature Superconducting ◽  
Power Stations ◽  
Field Cooling

In this paper, the magnetostriction and stress of an orthotropic mechanical high-temperature superconducting disk with a concentric small hole are investigated based on the exponential model of the critical state. Approximate solutions of the displacement and stress for the superconducting disk during zero-field cooling (ZFC) and field-cooling (FC) processes are obtained. The results show that tensile stresses will appear in the disk during the decreasing field of ZFC, while the stresses are always compressive during the increasing field of ZFC and FC processes. This indicates that the superconducting disk is easily damaged during the decreasing field of ZFC and FC processes. The critical point where tensile stress is largest is provided. The value of magnetostriction depends on the size of the disk, the applied field and the magnetization process. This research is helpful in the reliability design of high-temperature superconducting disks and cables with high strength for space solar power stations.

scholarly journals Multi-scale Method for the Crack Problem in Microstructural Materials

2010 ◽  
Vol 10 (1) ◽  
pp. 69-86 ◽  
Author(s):  
R. H. W. Hoppe ◽  
S.I. Petrova
Keyword(s):  
Finite Element ◽  
Crack Problem ◽  
Material Model ◽  
Superposition Method ◽  
The Finite Element Method ◽  
Multi Scale ◽  
Microscopic Models ◽  
Modeling Strategy ◽  
Porous Microstructures ◽  
Global And Local

AbstractThe paper deals with the numerical computation of a crack problem posed on microstructural heterogeneous materials containing multiple phases in the microstructure. The failure of such materials is a natural multi-scale effect since cracks typically nucleate in regions of defects on the microscopic scale. The modeling strategy for solving the crack problem concerns simultaneously the macroscopic and microscopic models. Our approach is based on an efficient combination of the homogenization technique and the mesh superposition method (s-version of the finite element method). The homogenized model relies on a double-scale asymptotic expansion of the displacement field. The mesh superposition method uses two independent (global and local) finite element meshes and the concept of superposing the local mesh arbitrarily on the global continuous mesh. The crack is treated by the local mesh and the homogenized material model is considered on the global mesh. Numerical experiments for problems on biomorphic microcellular ceramic templates with porous microstructures of different materials constituents are presented.

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