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08 June 2010, Volume 32 Issue 3
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    Application study
    STUDY ON NONPLANAR NONLINEAR DYNAMICS OF ICED CABLE
    CUI Yamei ZHANG Wei YAO Minghui
    2010, 32(3):  92-95.  doi:10.6052/1000-0879-2008-225
    Abstract ( 1363 )   PDF (650KB) ( 647 )  
    In this paper, the nonlinear, nonplanar, complicated dynamics of the small sag, iced cable subjected to side wind and movement of one support is investigated. Based on theories of analytical mechanics, elastic mechanics and aerodynamics, the nonlinear partial differential equations with three-degree-of-freedom are established. Then, the dimensionless method and the Galerkin's method are applied to discretize the governing partial equations of a three-degree-of-freedom nonlinear system. And then, the method of multiple scales is used to obtain the averaged equations of the iced cable system in the case of primary resonance and 2:1 internal resonances. Finally, numerical simulation is employed to find the nonlinear dynamic responses of the iced cable system. It is found there exist the periodic motion, multi-period motion, quasi-periodic and chaotic motions for the iced cable under certain conditions.
    Education Study
    Application of MATLAB to Kinetics
    KAN Wen-Bin LI tong YE Chunjie
    2010, 32(3):  118-119.  doi:10.6052/1000-0879-2008-278
    Abstract ( 1660 )   PDF (433KB) ( 1066 )  
    The methodology of the paper is coherent, i.e., seeking problems from instruction, using mechanical analysis as a dominant method, based on which to design procedure algorithms, aided with high-efficient computing software MATLAB, meditating further on nature of the problems according to the simulating results. It solved the problem of the famous PASCAL's cycloid, of which the kinetics parameters is outputted in form of a matrix; and it solved a case of resultant motion whose absolute kinetics trajectory is unimaginable, by programming a general-purpose procedure to probe on its charming trajectory. This paper also solved the simulation of an ellipse-generating mechanism. All the procedures the paper presented can be utilized to visualize the abstract mechanics for the purpose of instructional presentations.
    2010, 32(3):  114-115.  doi:10.6052/1000-0879-2008-414
    Abstract ( 1394 )   PDF (241KB) ( 445 )  
    Interesting mechanics story
    2010, 32(3):  136-138.  doi:10.6052/1000-0879-2008-537
    Abstract ( 1238 )   PDF (226KB) ( 904 )  
    Application study
    2010, 32(3):  68-70.  doi:10.6052/1000-0879-2009-027
    Abstract ( 1072 )   PDF (478KB) ( 588 )  
    The loading cable tension is a basic design parameter for Solid Cargo Supplying. From the standard curve of catenary, the maximal tension and the length of the loading cable in the condition of loading or without loading are obtain based on the parabola equation, and an application example is given, which could provide a reference for the design of Solid Cargo Supplying.
    2010, 32(3):  71-76.  doi:10.6052/1000-0879-2009-056
    Abstract ( 1009 )   PDF (2419KB) ( 491 )  
    In wind field of category C ground feature, numerical simulation of static wind load and wind field were performed for single buildings group composed of three buildings by CFD. Tetrahedron discrete grid with good adaptability has be adopted in this paper. The wind pressure coefficient in various spacings at any wind angle are simulated and analyzed. Distribution laws and characteristics of wind pressure coefficient interference factor on this kind of building surface following the change of spacing at any wind angle have been obtained. The result of numerical simulation could provide basis for building groups distribution optimization and wind-resistant design of structures.
    THE MODELING AND SIMULATION OF CLUSTER MUNITION DYNAMIC DISPERSION
    ZHENG Yousheng YANG Jianying WANG Liangming
    2010, 32(3):  85-88.  doi:10.6052/1000-0879-2009-063
    Abstract ( 1143 )   PDF (725KB) ( 715 )  
    According to the submunition and mainmunition movement, a complete cluster munition dynamic dispersion flight mechanical model is established, which includes the cluster munition motion feature and the bullet motion laws in and out of the projectile body. In addition, according to the action performance requirements, the powder mass and pressure in the burning chamber can be estimated for relection of necessary propellant quantity. This study provides a reference for engineering design.
    2010, 32(3):  89-91.  doi:10.6052/1000-0879-2009-090
    Abstract ( 1402 )   PDF (479KB) ( 1220 )  
    Based on a rotor model, the coupled torsional-axial vibration is analyzed. Calculation results show that the prestress and the rotational centrifugal load may influence the torsional vibration frequency of a rotor. The torsional vibration frequency will increase when the prestress is increased. The axial vibration frequency is not influenced because the direction of the prestress is perpendicular to the axis. The coupled torsional-axial vibration may take place when the torsional vibration frequency is increased due to the prestress.
    THEORETICAL ANALYSIS OF THE SOIL-ARC MECHANISM BETWEEN SOILS AND REINFORCING PILES
    WEI Zuoan ZHOU Yongkun WAN Ling ZHOU Ying DAI Gaofei
    2010, 32(3):  57-61.  doi:10.6052/1000-0879-2009-174
    Abstract ( 1442 )   PDF (770KB) ( 600 )  
    Anti-slide pile is a major landslide prevention measure. This paper analyzes the transition process of force between soil and anti-slide pile based on force equilibrium. According to the relationship of acting force and reacting force between soil and anti-slide pile, the stress distribution in the soil behind anti-slide pile is obtained. From the stress isograms, it is shown that the mechanism of soil arc between anti-slide pile and soil is the result of the stress state from imbalance to balance in soil.
    Education Study
    2010, 32(3):  123-125.  doi:10.6052/1000-0879-2009-202
    Abstract ( 985 )   PDF (585KB) ( 440 )  
    Based on the situation of mechanics teaching of higher vocational education of China and the direction of course system reform, the six of issues on mechanics teaching were analyzed, the main cause of these problems protruded is conflict between the universal content of engineering mechanics and the special requirement from skill foster, but the mechanics education is not inconsistence to professional training, and the suggestions on reinforce mechanics teaching of higher vocational education orientated from the Chinese society of theoretical and applied mechanics-CSTAM and the subdivisions of all provinces had been proposed., the course standard and teachers’ attainment are needed for the education system.
    Application study
    FLOW EXPERIMENTS OF HPAM SOLUTION IN QUARTZ MICRO-TUBES
    YUE Xiang'an WANG Nan ZHANG Lijuan WANG Fei
    2010, 32(3):  81-84.  doi:10.6052/1000-0879-2009-207
    Abstract ( 1149 )   PDF (638KB) ( 538 )  
    To study the complex flow characteristics of polymer solution in reservoir porosity, experiments were carried out for the flow of partially hydrolyzed polyacrylamide (HPAM) solution in tubes of 10$\sim$350$\mu$m in diameter. The results show that under the experimental conditions specified in this paper, the flow laws of HAPM solution significantly deviate from those of non-Newtonian fluid mechanics in conventional scales. When the diameter of tubes is small, its average cross-section flow velocity is higher than the conventional result. The smaller the tube diameter, the greater the deviation will be.
    2010, 32(3):  50-56.  doi:10.6052/1000-0879-2009-217
    Abstract ( 1285 )   PDF (1547KB) ( 711 )  
    A 3D irregular deformable discrete element model is developed to model the brittle failure process of rock materials. Under the external loadings, continuous blocks near the failure limits are cut into several smaller blocks, and connect-type springs are assigned on the interface between these blocks. Under the tension-shear failure criterion, the connect-type springs are broken into the contact-type springs. As a result, a continuous-discontinuous modeling of brittle failure of rock materials is implemented. Dynamic relaxation technique is applied to obtain solutions without assembling the global matrix. The model is validated by typical examples.
    Mechanics History
    2010, 32(3):  128-132.  doi:10.6052/1000-0879-2009-225
    Abstract ( 1399 )   PDF (1610KB) ( 746 )  
    Application study
    2010, 32(3):  35-40.  doi:10.6052/1000-0879-2009-226
    Abstract ( 1188 )   PDF (1218KB) ( 577 )  
    This paper proposes a method for quantitative testing of plastic deformation and damage in steel members during the process of loading. The Diffuse-Reflectance Method was used to obtain varied images of surface roughness of steel specimen during the process of stretching. With a further treatment of these images, the average gray value variations can be obtained to reflect the steel specimen surface roughness, which will help us to find out the sensitive parameter relevant to plastic deformation and damage status in the steel member under loading. The results show that, based on Diffuse-Reflectance Method and image processing, the average gray value variations of steel specimen's surface roughness during the loading process could be used to detect the start of plastic deformation and to describe the damage degree quantitatively in the late stage of plastic deformation of metal components or structures.
    THE NUMERICAL STUDY OF INFLUENCE OF BODY SHAPE ON CARANGIFORM
    JING Jun XU Jian LIANG Zhonggang
    2010, 32(3):  26-30.  doi:10.6052/1000-0879-2009-236
    Abstract ( 1076 )   PDF (1736KB) ( 639 )  
    The carangiform propulsion has been paid much attention in recent years. In nature, the fish may have many kinds of tail shape, but only a few body shapes. This paper studies the influence of the body shape on the carangiform propulsion. Two body models are used in numerical simulation: model A, the fish normal body shape; model B, the submarine shape. The tail takes a crescent shape. The strouhal number ($St$) is chosen as the main parameter, and the combined translational-rotational oscillations are taken as the motion of tail. The hydrodynamical force is calculated by the software FLUENT. The results show that the body shape does affect the carangiform propulsion, the fish body shape is beneficial to cruising as a result of the nature evolutional selection.
    2010, 32(3):  62-67.  doi:10.6052/1000-0879-2009-249
    Abstract ( 1261 )   PDF (1186KB) ( 553 )  
    Steel ejector tube is widely used in aviation and chemical industries as an exhaust apparatus in product experiments. However, the internal high-speed airflow can result in a large number of longitudinal cracks around the cylinder. It is related with vibration modes and frequencies, as well as the stress level of the ejector tube. In this work, the petal breathing vibration mode and frequency corresponding to the longitudinal cracks in a large ejector tube structure are studied using FE analysis. With dynamic stress analysis, the frequency which leads to damage of ejector tube is found mainly in the low frequency band of 200$\sim $300\,Hz. A typical breathing vibration mode and frequency were obtained through experiments, which shows that the numerical modeling and analysis are reasonable.
    Education Study
    Application study
    A KIND OF CONSTITUTIVE MODEL OF TiNi IMPORTED TO ABAQUS
    DENG Shichun HU Xiuzhang LI Yongchi
    2010, 32(3):  31-34.  doi:10.6052/1000-0879-2009-279
    Abstract ( 1401 )   PDF (640KB) ( 896 )  
    Tang's model was simplified and extended to three dimensional space based on the assumption in plasticity theory. A user defined material subroutine (UMAT) is developed for ABAQUS application. Simulations for quasi-static tensile experiments with the pseudoelastic TiNi alloy specimen are conducted and the results agree well with the experimental data.
    2010, 32(3):  22-25.  doi:10.6052/1000-0879-2009-308
    Abstract ( 1005 )   PDF (716KB) ( 527 )  
    Taking advantages of the best features of flow-condition-based interpolation and split scheme, this paper proposes a flow-condition-based interpolation split scheme (FCBIS). A two dimensional triangle fluid element is built and a corresponding program is developed. The solution procedure is discussed and the numerical example solution is given to illustrate the efficiency and accuracy of the procedure.
    2010, 32(3):  16-21.  doi:10.6052/1000-0879-2009-344
    Abstract ( 1365 )   PDF (901KB) ( 587 )  
    The meshless method is used to solve problems with moving boundaries, A method is proposed for dealing with unsteady flow with movable and torsional boundaries in small scale. The moving principle for discrete points in meshless method is formulated, the spring analogy is modified to consider the movements of points, the adaptability and precision of the analogy are enhanced. ALE equations are solved based on meshless method. Based on clouds, the spatial derivatives are approximated by using local least-squares curve fitting and the numerical flux is calculated with HLLC scheme, a multistage Runge-Kutta algorithm is used to advance the equation in time. The oscillating flow of representative airfoils in transonic and supersonic conditions is simulated. The computational results agree well with the experiment data, which indicates that the method is valid.
    AN ANALYSIS OF THE VEHICLE SEAT BELT ANCHORAGE STRENGTH BASED ON
    XU Zaolong FAN Chaobing LIAO Shanquan XIA Gangzhen
    2010, 32(3):  105-110.  doi:10.6052/1000-0879-2009-356
    Abstract ( 1309 )   PDF (4362KB) ( 1337 )  
    The explicit solution method in LS-DYNA is used to carry out an analysis of the seat belt anchorage strength of a cross-over minivan. The whole BIW model is included, specified load condition is used according to the national standard, an accurate prediction is made on whether the structure can meet the standard, and results are obtained for the structure optimization. This approach can be extended to other quasi-static problems.
    2010, 32(3):  77-80.  doi:10.6052/1000-0879-2009-358
    Abstract ( 1324 )   PDF (675KB) ( 574 )  
    To improve the capability of energy absorption, a new type of polyurethane foams is designed and produced; the process of the blast wave propagating into this material is investigated. The main design principle of the material is as follows: by adding a certain amount of metallic particles with diameter of about 10\,$\mu$m into polyurethane foams, the heat absorption capacity of the material is enhanced so that its capacity for resisting blast is improved. The pressures of blast wave propagating into polyurethane foams with or without metallic particles, and with different amounts of metallic particles, are measured by using piezoelectric pressure transducers, respectively. The results show that the polyurethane foams with metallic particles have a better performance in resisting blast wave than those without metallic particles.
    Education Study
    2010, 32(3):  126-127.  doi:10.6052/1000-0879-2009-366
    Abstract ( 1249 )   PDF (419KB) ( 457 )  
    Application study
    2010, 32(3):  96-100.  doi:10.6052/1000-0879-2009-381
    Abstract ( 1489 )   PDF (802KB) ( 500 )  
    The mixed time integration parallel algorithm for structural nonlinear dynamic analysis is proposed, which combines the implicit and explicit time integration techniques. The parallel algorithm with mixed time integration technique is implemented with domain decomposition. Concurrency is introduced into this algorithm by integrating interface nodes with the explicit time integration technique and solving local subdomains with an implicit algorithm. A flexible parallel data structure is designed to implement the parallel mixed time integration algorithm. A computer program is developed with messaging interface as the software development environment. Numerical example is implemented to validate the performance of the parallel algorithm. It is shown that the proposed algorithm is better in performance than the implicit algorithm.
    2010, 32(3):  41-43.  doi:10.6052/1000-0879-2009-384
    Abstract ( 1497 )   PDF (412KB) ( 577 )  
    The buckling and post-buckling behaviors of a column under distributed load are discussed in this paper. Based on the large deformation theory and considering the axial extension of the column, the equilibrium equations with geometric nonlinearity of an elastic column subjected to distributed load are established. By using shooting method and analytical continuation, the nonlinear boundary-value problem is solved numerically. The post-bucking configuration and equilibrium paths of the column are obtained.
    Education Study
    Movement of slider on a plan
    Zhaohui Qi Zhihao Huang Luo Xiaoming
    2010, 32(3):  120-121.  doi:10.6052/1000-0879-2009-389
    Abstract ( 1220 )   PDF (285KB) ( 614 )  
    Under the assumption of rigid ground plan, the equations that control the movement of a slider on the plan are ambiguous and no solution can be obtained from them. In this paper,we study this problem based on the elastic ground assumption and give an explanation of why friction can excite vibration according to the insight of the solutions.
    Application study
    2010, 32(3):  44-49.  doi:10.6052/1000-0879-2009-394
    Abstract ( 1497 )   PDF (991KB) ( 615 )  
    In this paper, Monte-Carlo method is used for the reliability analysis of elastic plane problems, in which the spline fictitious boundary element method (SFBEM) is used as the sample experiment approach due to its high accuracy and efficiency. In order to further improve the calculation, Taylor expansion and Neumann expansion techniques are adopted to avoid generating influence matrices and their inverses during the repeated calculations of a large number of sample analyses, and the calculation time of a single sample analysis is considerably reduced. In addition, an important sampling method is also used to reduce the sampling numbers while the same accuracy is maintained. Numerical results show that the proposed method, the Taylor-Neumann expansion important sampling Monte-Carlo SFBEM, can achieve a good accuracy and a relatively high efficiency for the reliability analysis.
    2010, 32(3):  101-104.  doi:10.6052/1000-0879-2009-399
    Abstract ( 1135 )   PDF (1079KB) ( 554 )  
    The multiplayer flat extrusion container is in a complicated condition and is difficult to be analyzed by FEM. With photoelastic method, the stress distribution, and stress concentration place can be obtained.In photoelastic experiments, soft-epoxy resin material was adopted for loaded medium. The results can serve as a basis in design of the flat extrusion container in practice.
    Review
    2010, 32(3):  10-15.  doi:10.6052/1000-0879-2009-449
    Abstract ( 1787 )   PDF (1441KB) ( 718 )  
    The Russian scientist of mathematics and medanics G.V. Kolosov introduced firstly the complex variable method to solve two-dimensional elasticity problems in 1909, which was then extended to fracture mechanics problems. In the past 100 years, the complex variable method has made great progresses. This year is the hundredth anniversary of the complex variable method of elasticity and fracture mechanics. This memorial paper summarizes research progresses of complex variable method in classical fracture mechanics, composite materials fracture mechanics, noval materials fracture mechanics and fracture problems for three dimensinal bodies.
    Education Study
    2010, 32(3):  116-117.  doi:10.6052/1000-0879-2009-474
    Abstract ( 1142 )   PDF (272KB) ( 579 )  
    The formula of restitution coefficient for the collision of rigid body in general motion is derived.
    On Appell's theoretical Mechanics
    MEI Fengxiang
    2010, 32(3):  111-112.  doi:10.6052/1000-0879-2010-012
    Abstract ( 1096 )   PDF (378KB) ( 566 )  
    Review
    2010, 32(3):  1-9.  doi:10.6052/1000-0879-2010-127
    Abstract ( 1892 )   PDF (2477KB) ( 1126 )  
    The dynamics of nanoparticle-laden multiphase flow is a new and important research field. To understand the basic interaction between phases and their physical nature, some problems are studied, including the closure for particle general dynamic equations; the construction of the coagulation kernel; the fundamental interaction between particle dynamics and flow coherent structures; the theoretical analysis on collision rate and some engineering applications. A new general mathematical method for solving the general dynamic equation is proposed, and applied in some engineering problems.