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Youhe Zhou - One of the best experts on this subject based on the ideXlab platform.

  • inclined crack problem in a Rectangular Slab of superconductor under an electromagnetic force
    Journal of Applied Physics, 2013
    Co-Authors: Xin Wang, Huadong Yong, Cun Xue, Youhe Zhou
    Abstract:

    In this paper, the critical state Bean model is employed to estimate the effect of the electromagnetic force on the fracture behavior of the superconductor Slab. The superconductor Slab with an inclined crack is subjected to an applied field. Based on the finite element method, the stress intensity factors are computed for two activation processes, zero field cooling and field cooling. Numerical results obtained show that the crack length and the inclined angle have significant effects on the fracture behavior. Generally, maximum of mode-I stress intensity factor is larger than that of mode-II stress intensity factor. The stress intensity factors analyzed in the paper are useful to learn fracture behavior and mechanical failure of superconductors.

  • effect of flux creep and viscous flux flow on flux pinning induced stress and magnetostriction in a long Rectangular Slab superconductor
    Journal of Applied Physics, 2010
    Co-Authors: Huadong Yong, Youhe Zhou
    Abstract:

    The magnetoelastic problem for a superconductor Slab placed in a time-dependent magnetic field is considered. Two major components of the flux (vortex) motion: flux creep and viscous flux flow have been considered, among which the logarithmic dependence of activation energy on the current density is assumed for the creep problem. As one of the two parts of flux motion, viscous effect of flux flow dominates the motion of fluxoids at high flux velocities and enhances the maximum tensile stress and the magnetostriction remarkably after zero-field cooling. However, the effect of flux creep cannot be omitted at low magnetic field sweep rate (Ba) and is helpful to alleviate tensile stresses within the superconductor. Apart from this, the position (x0) where the maximum tensile stress occurs has a similar dependence on the sweep rate (Ba) as the stress value itself. All the results indicate that the sweep rate (Ba) should be considered in the magnetization process in order to avoid cracking within the superco...

  • fracture behavior for a long center slant cracked Rectangular Slab of superconductor under electromagnetic force
    Modern Physics Letters B, 2009
    Co-Authors: Youhe Zhou, Zhiwen Gao
    Abstract:

    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.

  • crack growth for a long Rectangular Slab of superconducting trapped field magnets
    Superconductor Science and Technology, 2008
    Co-Authors: Zhiwen Gao, Youhe Zhou
    Abstract:

    We use numerically evaluated contour integrals and crack length versus time analysis to simulate crack propagation based on electromagnetic forces for superconducting trapped-field magnets. The coupling finite element and infinite element method has been employed in the numerical analysis. In this paper an interior elliptical crack is allowed to grow based on the critical stress criterion. Stress intensity factors and J integrals are estimated during field descent. Crack propagation is modeled by the change of crack length with time, and contours of the Mises equivalent stress at the final stage of the crack propagation are shown.

  • crack inclusion problem for a long Rectangular Slab of superconductor under an electromagnetic force
    Computational Materials Science, 2007
    Co-Authors: Youhe Zhou
    Abstract:

    Abstract The interaction between a crack and an inclusion in a type-II superconductor is investigated in this paper. Using the finite element method, the crack–inclusion problem can be solved. Numerical results are presented to illustrate fracture behavior of superconductor under electromagnetic force. The magnetic behavior of the superconductor is described by the critical-state Bean model. The stress intensity factors at the crack tip are obtained and discussed for decreasing field after zero-field cooling. Numerical results show that the stress intensity factors at crack tip are always larger with an elastic inclusion than for a rigid inclusion. Because of the barrier effect of the rigid inclusion, the values of the stress intensity factors decrease when the crack approaches the inclusion. Relative to rigid inclusion and no inclusion cases, elastic inclusion leads to the largest value of the stress intensity factor at crack tip. Thus, the crack propagation is easier near an elastic inclusion and the rigid inclusion is helpful for crack arrest.

Huadong Yong - One of the best experts on this subject based on the ideXlab platform.

  • inclined crack problem in a Rectangular Slab of superconductor under an electromagnetic force
    Journal of Applied Physics, 2013
    Co-Authors: Xin Wang, Huadong Yong, Cun Xue, Youhe Zhou
    Abstract:

    In this paper, the critical state Bean model is employed to estimate the effect of the electromagnetic force on the fracture behavior of the superconductor Slab. The superconductor Slab with an inclined crack is subjected to an applied field. Based on the finite element method, the stress intensity factors are computed for two activation processes, zero field cooling and field cooling. Numerical results obtained show that the crack length and the inclined angle have significant effects on the fracture behavior. Generally, maximum of mode-I stress intensity factor is larger than that of mode-II stress intensity factor. The stress intensity factors analyzed in the paper are useful to learn fracture behavior and mechanical failure of superconductors.

  • effect of flux creep and viscous flux flow on flux pinning induced stress and magnetostriction in a long Rectangular Slab superconductor
    Journal of Applied Physics, 2010
    Co-Authors: Huadong Yong, Youhe Zhou
    Abstract:

    The magnetoelastic problem for a superconductor Slab placed in a time-dependent magnetic field is considered. Two major components of the flux (vortex) motion: flux creep and viscous flux flow have been considered, among which the logarithmic dependence of activation energy on the current density is assumed for the creep problem. As one of the two parts of flux motion, viscous effect of flux flow dominates the motion of fluxoids at high flux velocities and enhances the maximum tensile stress and the magnetostriction remarkably after zero-field cooling. However, the effect of flux creep cannot be omitted at low magnetic field sweep rate (Ba) and is helpful to alleviate tensile stresses within the superconductor. Apart from this, the position (x0) where the maximum tensile stress occurs has a similar dependence on the sweep rate (Ba) as the stress value itself. All the results indicate that the sweep rate (Ba) should be considered in the magnetization process in order to avoid cracking within the superco...

X Han - One of the best experts on this subject based on the ideXlab platform.

  • flux pinning induced stress and magnetostriction in a functionally graded long Rectangular superconductor Slab
    Journal of Applied Physics, 2011
    Co-Authors: W J Feng, X Han
    Abstract:

    The flux-pinning-induced stress and magnetostriction of a functionally graded type-II superconductor shaped as a Rectangular Slab are analyzed. By using the plane strain approach, the exact solution of the three-dimensional (3D) magneto-elastic problem is found. All the stresses, strains, and magnetostriction in the graded direction are first expressed in terms of the flux-density profile in the Slab, and all these expressions are valid for any critical-state model jc=jc(B). Then, based on the Bean model, i.e., jc=const, an extensive analysis is made for three cases of applied magnetic fields, i.e., increasing field, decreasing field, and field cooling. And the emphasis is put on the effects of both the applied magnetic field and the graded index of the Slab on the maximum tensile stress and the magnetostriction.

Vijay B. Patil - One of the best experts on this subject based on the ideXlab platform.

Xiaohang Li - One of the best experts on this subject based on the ideXlab platform.

  • impact of viscous flux flow on the stress in long Rectangular Slab superconductors
    Journal of Applied Physics, 2010
    Co-Authors: Yong Yang, Liye Xiao, Xiaohang Li
    Abstract:

    We have attempted to resolve the influence of the rate (dBa/dt), at which an external magnetic field Ba is swept down, on the tensile stress in bulk type-II superconductors. The effect of viscous flux velocity (υ0) on the stress is discussed for two magnetization processes: the decreasing field after zero-field cooling (ZFC) and the field cooling (FC). With increasing υ0, the maximum tensile stress increases in ZFC and keeps constant in FC when the position x0, at which the remagnetization front is located, changes. x0 moves away from the center of the superconductor with increasing υ0. The effect of dba/dt, which is a parameter for dBa/dt, on the stress is similar to the effect of υ0. These results imply that dBa/dt must be considered in the magnetization processes in order to avoid cracking in type-II bulk superconductor.