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15 June 2015, Volume 37 Issue 3
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    Review
    2015, 37(3):  287-294.  doi:10.6052/1000-0879-15-089
    Abstract ( 703 )   PDF (10999KB) ( 633 )  

    The rockburst (rock burst) is a peculiar, abnormal, localized, isolated, delayed, sudden and damaging phenomenon associated with the underground rock excavation. Several hours after the completion of the excavation, some parts of the in-situ intact rock wall might be actively, suddenly and vigorously ejected, thrown and blown off from the original wall into the excavated open space, with high initial ejecting velocity and kinetic energy. It often causes fatality, injury and damage because its occurrence is usually unforeseeable and unpredictable. The rockburst is still a worldwide tough problem that puzzles the international communities of rock mechanics in spite of tremendous research efforts over the past 50 years. This paper puts forward a hypothesis of micro-fluid inclusions as the cause and mechanism of the rockburst. The fluid inclusions in the micro-voids of intact rocks may have a high initial pressure equaling to the average of the three in-situ principal stresses. The fluid inclusions with a high initial pressure can have a high expansion power. They can flow, migrate and turn from the liquid phase into the gas phase after the rock excavation. Their physical and chemical expansion power can cause the rockburst of the excavated intact rock wall. This hypothesis offers effective solutions for the rockburst problem to reduce and eliminate its damage.

    STRUCTURES, MECHANICAL PROPERTIES AND APPLICATIONS OF FLEXIBLE ELECTRONIC COMPONENTS
    LI Xuetong, TONG Hongyue, ZHAO Yue, DU Fengshan
    2015, 37(3):  295-301,325.  doi:10.6052/1000-0879-14-147
    Abstract ( 658 )   PDF (11884KB) ( 1577 )  
    The new structures of the flexible electronic components with high stretching ability have a great application potential for electronic systems as against the established wafer based technologies. The stretchable and flexible technologies offer the performance of conventional rigid devices, but with the ability to be stretched, compressed and bended, which might find important applications in the fields of health monitoring systems and epidermal electronics. The study of flexible circuits and their mechanical properties can improve the stretching ability of the systems. This paper reviews their structures and applications in systems ranging from the hemispherical electronic eye to the flexible solar panels, and analyses the mechanical properties of stretchable electronic components, and discusses some directions for further researches.
    TIMOSHENKO BEAM THEORY AND ITS APPLICATIONS
    XIA Guiyun, ZENG Qingyuan
    2015, 37(3):  302-316.  doi:10.6052/1000-0879-14-080
    Abstract ( 763 )   PDF (503KB) ( 2128 )  

    This paper reviews the developments of the Timoshenko beam theory with consideration of the shear deformation, the calculations of the shear correction factors, the linear and geometrically nonlinear finite elements of the Timoshenko beam, the material nonlinerity analysis, the vibrating theories, the stability theories, the coupling theories of the shear lag and the shear deformation and the coupling theories of the distorsion and the shear deformation in a box beam, the shear deformation effect on the composite box girder with corrugated steel webs, the elastic foundation beam, and the applications in civil engineering.

    Applied Research
    STOCHASTIC ANALYSIS OF THE COUPLED PROCESS OF SEEPAGE FIELD AND STRESS FIELD
    ZHANG Tong, LIU Weiqun, TANG Juny, YI Zhengfeng
    2015, 37(3):  317-320,360.  doi:10.6052/1000-0879-15-014
    Abstract ( 337 )   PDF (1646KB) ( 952 )  
    Based on the influence of the stochastic nature of the parameter in the perturbation stochastic FEM (finite element method) on the coupled process of the seepage field and the stress field, finite element iterative formulas are derived, where the permeability coeffcient and the elasticity modulus are set as the basic stochastic quantities, and accordingly, the stochastic calculating programs used for calculating the seepage field and the stress field separately are re-formulated. By utilizing the improved programs, the H-M problem of a dam is calculated, and the results are compared with those calculated by COMSOL Multiphysics. It is shown that these two methods are consistent, which indicates that for fluid-solid coupling problems in engineering practice, the stochastic characteristics can be obtained by the program, which is not available in the commercial software.
    2015, 37(3):  321-325.  doi:10.6052/1000-0879-14-290
    Abstract ( 274 )   PDF (1416KB) ( 589 )  
    To improve the calculation accuracy of the Swedish slice method, the interaction forces are usually to be considered. Based on the physical nature, this paper proposes the partial and whole hydraulic pressure methods to analyze the stability of the saturated underwater slope. These methods are used to discriminate two conflicting formulas in the Swedish slice method. It is pointed out that one formula has a lower accuracy because the vertical components of the soil slice's top surface and the bottom water pressure are directly taken to build the equations of equilibrium, and the impact of the horizontal components is ignored. It is also pointed out that these two methods can be universally used to improve the calculation accuracy of the analysis of the saturated slope.
    FATIGUE ANALYSIS OF THE AIR SPRINGS OF THE RAIL VEHICLES
    LI Zhichao, LI Xuebing, LIU Wanqiang, HE Yuan, WANG Hao, DING Zhiping, WEI Yintao
    2015, 37(3):  326-331.  doi:10.6052/1000-0879-14-257
    Abstract ( 352 )   PDF (11641KB) ( 434 )  
    The fatigue analysis based on the theory of the cracking energy density(CED) is carried out to predict the fatigue life of the air spring. The finite element simulation of the air spring system with an auxiliary chamber is made, and the strain history of each element's center for the air spring capsule is obtained. The strain history obtained by the simulation is substituted into the CED formula to calculate the CED peak of all possible cracking plane for each element's center. The CED peak is used to calculate the related tearing energy's peak. The corresponding equivalent tearing energy is calculated. Finally, the equivalent tearing energy is used to calculate the crack's propagation rate and the corresponding fatigue life of all possible cracking plane for each element's center. Comparing the predicted fatigue's life with experimentally obtained fatigue's life, it is shown that the predicted fatigue's life is 1.91 times of the experimentally obtained fatigue's life, which verifies the reliability of the model and the method of the fatigue simulation.
    ANALYSIS OF MECHANICAL PERFORMANCE OF CANTED COIL SPRING BY ANSYS
    WANG Jianping, LI Jian, HUANG Wei, ZHAO Teng
    2015, 37(3):  332-337,349.  doi:10.6052/1000-0879-14-258
    Abstract ( 718 )   PDF (10243KB) ( 787 )  
    The canted coil spring is widely used in the medical equipment, the high-voltage switch, the auto industry and other fields. Because of its special structure and complex stress state, there is no effective theoret-ical calculation method to obtain the load-displacement curves except for experimental and numerical methods. In this paper a finite element model of the canted coil spring is established on the ANSYS software platform to obtain its load-displacement curves. The relationships of the wire diameter, the pitch, the magnitude of inclina-tion of the canted coil spring with its load-displacement curve and the stiffness under a fixed load displacement condition are analyzed. The deformations of the canted coil spring under the working condition are studied. The calculation results provide a theoretical basis for the optimization design and the application of the canted coil spring.
    2015, 37(3):  338-343.  doi:10.6052/1000-0879-14-262
    Abstract ( 366 )   PDF (2270KB) ( 638 )  
    A toroidal weak form quadrature shell element is established based on the thin shell theory. Some static and free vibration problems of circular and elliptic toroidal shells are studied. High accuracy and com-putational effciency are achieved in the quadrature element analysis of numerical examples as compared with the finite element and analytical solutions. It is found that the ratio between the major and minor axes has a significant influence on the accuracy and the convergence rate for elliptic toroidal shells.
    2015, 37(3):  344-349.  doi:10.6052/1000-0879-14-371
    Abstract ( 346 )   PDF (2833KB) ( 523 )  
    Based on the thin shell theory and the viscoelastic theory, the modal characteristics of a viscoelastic laminated cantilever thin cylindrical shell are obtained by a semi-analytical method. Firstly, the dynamic model for the host shell and the constraining layer is established based on the Love's shell theory combining with the consideration of the deformation coordination and the interatomic forces of the viscoelastic damping layer, and the first-order ordinary differential equations of the whole component are derived in the state vectors by the transfer matrix method. Then, the natural frequencies, the modal loss factor and the three-dimensional modal shapes are obtained by means of a high-precise integration method, which are compared with the results by the finite element method. The example results show that the transfer matrix method is effective to obtain the modal vibration characteristics of the viscoelastic laminated cantilever thin cylindrical shell.
    2015, 37(3):  350-354.  doi:10.6052/1000-0879-14-241
    Abstract ( 316 )   PDF (3301KB) ( 503 )  
    The temperature will induce thermal stresses in the coal body and lead to fractures and even an abruption, which might improve the gas extraction. Based on the finite element software RFPA, the process of fracturing during heating is simulated, and the evolution of coal fracturing at different temperatures is revealed. Using the acoustic emission technique, the internal fissures of the coal are identified under different temperatures and confining pressures. The results are compared and it is shown that the thermal stress generated by the temperature can raise the coal temperature, destroy the original cleat system, and produce new cracks. When the temperature reaches to a certain value, the porosity fracture of the internal coal expands, the main cracks are formed, the effective penetration channel is enlarged, the adsorption capacity of the coal is reduced, the content of the free gas is increased, and the penetration is significantly increased. The work might provide some insight in preventing the mine disaster due to the gas, and also for the gas extraction.
    2015, 37(3):  355-360.  doi:10.6052/1000-0879-14-284
    Abstract ( 251 )   PDF (8500KB) ( 732 )  
    A pseudo-dynamic test is carried out to study the seismic performance of the T steel semi-rigid connection steel frame under two kinds of earthquake peak acceleration, and the peak strain, the displacement and the load variation of the T steel connection steel frame with and without the vertical load are analyzed and compared, together with the load-displacement hysteresis curves. Experimental results show that the T steel semi-rigid connection steel frame enjoys better deformation capacity and ductility performance, and the hysteretic performance is good, that explains the good seismic performance.The dynamic response is increased with the increase of the earthquake load; the vertical load has a great effect on the displacement response, but has little effect on the strain and the interlayer load for the semi-rigid connection steel frame.
    2015, 37(3):  361-366.  doi:10.6052/1000-0879-14-251
    Abstract ( 461 )   PDF (885KB) ( 1095 )  
    The 3D rigid pendulum is a simplified mechanical model of the GEO (Geostationary) stationary spacecraft, and it is a rigid body with three rotational degrees of freedom, connected with a fixed pivot without consideration of the friction. The attitude dynamics equations of the 3D rigid pendulum based on the modified Rodrigues parameters are derived in this paper. For the 3D rigid pendulum's attitude and angular velocity stability as a nonlinear control design problem, by using the energy method, the system controller is designed based on the passive control theory. It is shown that the system can meet the passive condition. By constructing the system's Lyapunov function, the attitude control law of the 3D rigid pendulum is obtained by using the energy method, and the LaSalle invariant principle is used to prove the asymptotic stability of the control law. The simulation results show that the attitude and angular velocity are asymptotically stable in the case of the inverted equilibrium and the simulation results verify the reliability of the method.
    THE MEASUREMENT OF THE ICE ADHESIVE FORCE FOR SURFACES OF DIFFERENT WETTABILITIES UNDER FREEZING RAIN
    WU Bin, YANG Qin, HE Jiming, TAN Sheng, CHEN Tian, LUO Yiming, LUO Zhuangzhu
    2015, 37(3):  367-371.  doi:10.6052/1000-0879-14-267
    Abstract ( 334 )   PDF (5440KB) ( 1014 )  
    The ice adhesive force is one of the key technical indicators for the anti-icing application of biomimetic superhydrophobics in many engineering fields. A measurement scheme for determining the ice adhesive force in real time by using the resistance strain gauge sensors is proposed, based on the principle that the strain of the icing samples during the cooling process is constrained by the ice adhesion. Via the data acquisition, the signal conversion and the software processing of the strain signals, the real-time monitoring and display of the strain sensing voltage are achieved. The ice adhesive force on the surfaces of different wettabilities is determined from the strain sensing voltage variation and the stress analysis of the samples. The results demonstrate that the real-time identification of the icing/melting behaviors and the ice adhesive force on surfaces of different wettabilities under cryogenic freezing environment is achieved by this measurement method.
    Research on Education
    2015, 37(3):  372-376.  doi:10.6052/1000-0879-15-055
    Abstract ( 339 )   PDF (955KB) ( 1333 )  
    2015, 37(3):  376-378.  doi:10.6052/1000-0879-14-179
    Abstract ( 614 )   PDF (553KB) ( 912 )  
    2015, 37(3):  378-380.  doi:10.6052/1000-0879-14-148
    Abstract ( 2302 )   PDF (322KB) ( 1244 )  
    2015, 37(3):  381-383.  doi:10.6052/1000-0879-14-122
    Abstract ( 475 )   PDF (982KB) ( 1451 )  
    Study on the teaching testing platform of "Experiment Structure Mechanics"
    CHEN Zaixian, WANG Huanding, WANG Rui, ZENG Sen
    2015, 37(3):  383-388.  doi:10.6052/1000-0879-14-066
    Abstract ( 326 )   PDF (12032KB) ( 428 )  
    History and Methodology of Mechanics
    Preface
    DAI Shiqiang
    2015, 37(3):  389-389. 
    Abstract ( 232 )   PDF (69KB) ( 1005 )  
    2015, 37(3):  390-394.  doi:10.6052/1000-0879-15-164
    Abstract ( 813 )   PDF (339KB) ( 1683 )  
    2015, 37(3):  395-396.  doi:10.6052/1000-0879-15-162
    Abstract ( 474 )   PDF (304KB) ( 1106 )  
    2015, 37(3):  397-400.  doi:10.6052/1000-0879-15-156
    Abstract ( 337 )   PDF (413KB) ( 571 )  
    Chongzhi Zu and pi
    WANG Zhendong, JIANG Nan
    2015, 37(3):  404-408.  doi:10.6052/1000-0879-15-160
    Abstract ( 544 )   PDF (19445KB) ( 2522 )  
    2015, 37(3):  409-417.  doi:10.6052/1000-0879-15-158
    Abstract ( 351 )   PDF (394KB) ( 686 )  
    2015, 37(3):  417-419.  doi:10.6052/1000-0879-15-161
    Abstract ( 514 )   PDF (338KB) ( 746 )  
    2015, 37(3):  420-425.  doi:10.6052/1000-0879-15-154
    Abstract ( 349 )   PDF (356KB) ( 724 )  
    2015, 37(3):  425-430.  doi:10.6052/1000-0879-15-159
    Abstract ( 379 )   PDF (351KB) ( 532 )  
    Nonlinear learning method and nonlinear sciences
    ZHANG Hongqing, MEI Jianqin
    2015, 37(3):  431-435.  doi:10.6052/1000-0879-15-165
    Abstract ( 717 )   PDF (1044KB) ( 1093 )  
    2015, 37(3):  436-440.  doi:10.6052/1000-0879-15-169
    Abstract ( 310 )   PDF (345KB) ( 696 )  
    2015, 37(3):  440-443.  doi:10.6052/1000-0879-15-163
    Abstract ( 298 )   PDF (715KB) ( 627 )  
    On nonlinear sciences and the applications in mechanics
    MEI Jianqin, ZHANG Hongqing
    2015, 37(3):  443-448.  doi:10.6052/1000-0879-15-157
    Abstract ( 527 )   PDF (3260KB) ( 1030 )  
    Reflections on reinforcement student's ability of mechanics modeling
    ZHANG Weiwei, LIANG Qingxiang, ZHAO Zilong, LI Chen
    2015, 37(3):  448-452.  doi:10.6052/1000-0879-15-166
    Abstract ( 351 )   PDF (1429KB) ( 628 )