Key Laboratory of Mechanics on Western Disaster and Environment

Lanzhou, China

Key Laboratory of Mechanics on Western Disaster and Environment

Lanzhou, China
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Hu W.,China Jiliang University | Xie L.,Key Laboratory of Mechanics on Western Disaster and Environment | Xie L.,Lanzhou University
AIP Conference Proceedings | Year: 2016

We present a model depicting the probability density function of the net charge transfer of the rebound saltating particles from the sand bed in sand-bed collision process. Using DEM simulation, the sand-bed collision process is simulated, and the difference of the contact areas between two collision particles is obtained. The net charge transfer of the rebound saltating particle is related to five variables, such as the particle sizes of both saltating particles and particles in sand bed, the incident velocity and incident angle of the saltating particle, and the contact angle. The probability density functions of the net charge transfer of the rebound saltating particle about five-random variables and two-random variables are demonstrated in this study. © 2016 Author(s).


Yong H.,Lanzhou University | Jing Z.,Lanzhou University | Zhou Y.,Key Laboratory of Mechanics on Western Disaster and Environment
Physica C: Superconductivity and its Applications | Year: 2012

The coupling effect between the mechanical behavior and the superconductivity is significant in deformable superconductors. In this article, electromechanical characterizations for the deformable superconductors in magnetic field are presented. We assume that the critical current density is independent of the magnetic field and strain effect on the critical current density is symmetric. The coupled partial differential equations are derived for the bulk superconductor. We quantitatively illustrate the effects of coupling parameters on the magnetostriction and magnetization. © 2012 Published by Elsevier B.V.


Tong D.,Key Laboratory of Mechanics on Western Disaster and Environment | Huang N.,Lanzhou University
Gongcheng Lixue/Engineering Mechanics | Year: 2011

Sand velocity in aeolian sand transport is measured using the PIV system (Particle Imaging Velocimetry) in a wind tunnel. The velocity probability distribution of ascending and descending particles, as well the influences of sand ripple on the sand particle motion are analyzed. The results show that velocity distributions of take-off particles and particles during sand movement accord with logarithm normal distribution. The mean incident velocity of sand particles is 1.005-1.4 times higher than take-off ones with different wind speed. It is found that sand ripples play an important role on the sand particles motion, which is a key factor that can not be neglected.


Yong H.,Key Laboratory of Mechanics on Western Disaster and Environment | Liu F.,Key Laboratory of Mechanics on Western Disaster and Environment | Zhou Y.,Lanzhou University
Applied Physics Letters | Year: 2010

The objective of this paper is to obtain the analytical solutions which satisfy the differential Ginzburg-Landau equations and some boundary conditions. Based on the linear deformation theory, the effects of prestrain on the wave function and magnetic potential of deformable superconductors have been investigated in the presence of a weak magnetic field. The results show that for the superconductors with a linearly elastic deformation, the wave function in the materials should be considered for two different cases, i.e., type I and type II. The prestrain effect in deformable superconductors should not be neglected in determining the superconductivity in superconductors. © 2010 American Institute of Physics.


Xie L.,Key Laboratory of Mechanics on Western Disaster and Environment | Xie L.,Lanzhou University | Li G.,Key Laboratory of Mechanics on Western Disaster and Environment | Li G.,Lanzhou University | And 4 more authors.
Journal of Applied Physics | Year: 2013

Contact electrification by collisions of homogenous particles is investigated by two-particle collision experiments, which reveals the relation between electrification and the diameter ratio and relative colliding velocity of the two particles. Then, based on researches reported by Grzybowskis research group, a statistical model to compute the net charge of electrified particle after a single collision and multiple collisions are established, respectively. The model shows the net charge carried by the electrified particles depends on the difference between the two surfaces' areas involved in collision contact and gives results in good agreement with our experiment results. © 2013 AIP Publishing LLC.


Gao Z.-W.,Key Laboratory of Mechanics on Western Disaster and Environment | Gao Z.-W.,Lanzhou University | Gao Z.-W.,Yonsei University | Zhou Y.-H.,Key Laboratory of Mechanics on Western Disaster and Environment | And 2 more authors.
Physica C: Superconductivity and its Applications | Year: 2010

The interaction of two collinear cracks is obtained for a type-II superconducting under electromagnetic force. Fracture analysis is performed by means of finite element method and the magnetic behavior of superconductor is described by the critical-state Bean model. The stress intensity factors at the crack tips can be obtained and discussed for decreasing field after zero-field cooling. It is revealed that the stress intensity factor decreases as applied field increases. The crack-tip stress intensity factors decrease when the distance between the two collinear cracks increases and the superconductors with smaller crack has more remarkable shielding effect than those with larger cracks. © 2010 Elsevier B.V. All rights reserved.


Gao Z.-W.,Key Laboratory of Mechanics on Western Disaster and Environment | Gao Z.-W.,Lanzhou University | Gao Z.-W.,Yonsei University | Zhou Y.-H.,Key Laboratory of Mechanics on Western Disaster and Environment | And 2 more authors.
Physica C: Superconductivity and its Applications | Year: 2010

YBa2Cu3Oy is an orthotropic material with different material properties in a, b and c directions, such as Young's modulus, coefficient of thermal expansion (CTE), and thermal conductivity. It is assumed that the material properties of inhomogeneous high temperature superconductor (HTS) vary with different height coordinate and temperature. A model is presented in this paper to calculate the thermal stress of inhomogeneous HTS when temperature decreases from ambient to operating conditions (cryogenic temperatures). By fitting a second order polynomial to the experimental data, value of the material properties of inhomogeneous HTS can be obtained. Then, through the proposed graded finite element method, the coupled thermo-mechanical equations were solved numerically. The numerical results show that the temperature profiles distribute the function of time after soaking. It is notable that the temperature profile reaches steady in a very short period of time, so the thermal stress suddenly increases to a very high level for a bulk superconductor. It is also shown that the closer to the sample internal region it is, the larger the heat fluxes are. Besides, the maximum tensile stresses, i.e. the peeling stresses, occur near bottom corner of inhomogeneous HTS. It is intended that the model presented in this paper could be useful to researchers who are interested in mechanical properties of inhomogeneous HTS. © 2010 Elsevier B.V. All rights reserved.


Yong H.,Key Laboratory of Mechanics on Western Disaster and Environment | Xue F.,Key Laboratory of Mechanics on Western Disaster and Environment | Zhou Y.,Key Laboratory of Mechanics on Western Disaster and Environment | Zhou Y.,Lanzhou University
Journal of Applied Physics | Year: 2010

In this paper, an analytical method is presented for determining the effective coherence length and order parameter in a superconductor. The interaction of the deformations of the crystal lattice with the superconducting condensate is considered. A simplified free energy has been used in the literature to estimate the effect of the prestrain on the coherence length and the order parameter. The exact solutions for three dimensional and plane strain problems are obtained. Based on the linear elastic theory, an extensive analysis is made during the positive and negative prestrain for the isotropic material. The results show that the effect of the prestrain on the superconductivity is appreciable. A comparison is made between three dimensional and two dimensional results, and there is not significant difference between the results for two conditions. These explicit solutions provide a convenient tool for evaluating the superconductivity when the material undergoes the deformation. © 2010 American Institute of Physics.


Gao Z.-W.,Key Laboratory of Mechanics on Western Disaster and Environment | Gao Z.-W.,Lanzhou University | Gao Z.-W.,Yonsei University | Zhou Y.-H.,Key Laboratory of Mechanics on Western Disaster and Environment | And 2 more authors.
Computational Materials Science | Year: 2010

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. © 2010 Elsevier B.V. All rights reserved.


Hu W.,Key Laboratory of Mechanics on Western Disaster and Environment | Hu W.,Lanzhou University | Xie L.,Key Laboratory of Mechanics on Western Disaster and Environment | Xie L.,Lanzhou University | And 2 more authors.
Applied Physics Letters | Year: 2012

Based on asymmetric contact, we present a contact charge model of high-energy trapped holes to predict the contact charging and explain the net charge transfer between identical silica glass surfaces in a single normal collision. Furthermore, the contact charging measurements are investigated on normal collisions of glassy particle-glassy particle-steel plane and glassy particle-glassy plane. The predicted results agree well with our experiments qualitatively and quantitatively: the impacting velocity and the particle size are two important factors affecting the magnitude of the contact charging. © 2012 American Institute of Physics.

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