Fracture analysis of Arc-shaped interfacial crack between a superconducting cylinder and its functionally graded coating

Significance 

Superconducting materials have a vast range of applications in several fields courtesy of their distinct properties. The use of these materials, however, is faced with various challenges such as fracture failure among others. Due to this problem, many different studies have been directed on crack analyses, especially in cylindrical superconducting composites. Although their magnetoelastic behaviors have been achieved through pre-existing research works, little is still known about their fracture properties of the interfacial cracks.

Compared with the existing crack problems in superconducting cylinder, it is a challenge for the fracture analysis on an interfacial crack between a homogeneous superconducting cylinder and its functionally graded superconducting coating.

Research conducted at Shijiazhuang Tiedao University in China by Professor Wenjie Feng and his PhD student Zhen Yan was aimed at establishing a novel mechanical model for an arc-shaped crack along the interface between a homogeneous superconducting cylinder and its functionally graded superconducting coating subjected to the action of transport currents along the symmetry axis of the superconducting cylinder. Their work is published in the journal, Composite Structures.

In their paper, by adopting the generalized Irie–Yamafuji model in the cylinder and the newly established extended generalized Irie-Yamafuji model in its coating, both the flux and current density distributions in the composite are given clearly in the processes of both transport current ascent and descent. On the other hand, the stress intensity factors and energy release rates at crack tips are further given in concise forms and numerically calculated by solving a system of linear algebra equations

Feng and Yan successfully uncovered some new phenomena concerning fracture properties that were initially not known to a good number of researchers. For instance, during current transport accent, the crack easily propagates and grows, while in the process of transport current descent, the propagation and growth of the crack come to a halt. Besides, the bigger the crack opening angle is, the easier the crack propagates. Also, either increasing the shear modulus graded index of the superconducting coating or decreasing the introduced critical state model parameters can impede crack propagation and growth.

According to the authors, the study will help in advancing the design, manufacturing, and applications of superconducting composites materials.

 

Fracture analysis on an arc-shaped interfacial crack between a superconducting cylinder and its functionally graded coating with transport currents. Advances in Engineering
Fig. 1. An arc-shaped interfacial crack between a superconducting cylinder and a functionally graded superconducting coating with generated flux under applied transport current: (a) superconducting composite model (as the transport current is saturated, the flux fills in the entire superconducting composite), (b) cross section of the composite

Fracture analysis on an arc-shaped interfacial crack between a superconducting cylinder and its functionally graded coating with transport currents 2. Advances in Engineering

About the author

Wenjie Feng received his B.S. degree from Lanzhou University, M.S. degree and Ph.D. degree in Solid Mechanics from Harbin Institute of Technology. He is a Chair Professor and Dean in Department of Engineering Mechanics at Shijiazhuang Tiedao University. Professor Feng is also the Visiting Professor in University of Hong Kong, Senior Visiting Scholar in University of Akron and Senior Researching Scholar in University of Siegen.

The major research fields of Professor Feng are (1) formal and inverse problems of elastic dynamics, (2) fracture mechanics and dynamics of advanced materials, (3) computer method in applied mechanics and engineering, and (4) mechanics behaviors of superconducting materials. He has finished four projects of National Science Fund of China and published over 120 SCI journal papers. One of these papers is chosen as the Most Cited Articles of Elsevier from 2004 to 2008.

He is serving as the editor for International Journal of Applied Mathematics and reviewers for about 40 internationally renowned journals, such as International Journal of Solids and Structure, Composite Structures and Computer Methods in Applied Mechanics and Engineering.

 

Reference

Feng, W., & Yan, Z. (2018). Fracture analysis on an arc-shaped interfacial crack between a superconducting cylinder and its functionally graded coating with transport currents. Composite Structures, 185, 338-347.

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