Applied Mechanics and Materials Vols. 94-96

Abstract: With the speed-up of subway, the discomfort problem of passengers caused by pressure waves becomes more and more serious. The prediction method of the pressure waves based on the one-dimensional unsteady compressible non-homentropic flow model and the method of characteristics is introduced, and the program is developed which can be used to calculate the pressure waves not only produced by single train passing through subway tunnel with airshafts, but also produced when the train starts or stops. On this base, the influence of the train speed and the cross-section area of airshafts to the comfort of passengers in the subway is researched. All these work provides the foundation for the development of the one-dimensional unsteady flow prediction method for pressure waves produced by the train passing through subway tunnel.

Abstract: Tai-Zhou Bridge, which has a three-tower and two-span, is 1080 meters long and 2 meters wide. The middle tower is a huge caisson foundation and chevron steel tower structure. It is important to make some effective technical measures to control the processes of caisson foundation’s installation, such as floating, orientation, implantation and final sunk, especially in complex conditions. Eroding model tests for the caisson foundation’s floating phase and sunken phase play an important role in the prophase installation. Information control technology could exactly guidance the sunk of cession. Finally, the linkage control of steel tower’s manufacture and operation is necessary for the precision of installation.

Abstract: A study on SEA properties of periodically stiffened structure was accomplished based on the periodic theory. With application of certain software, a simulation was performed on a common periodically stiffened fuselage structure. The results indicate such modeling approach reflects relatively accurate property of subsystem in mid and high frequency range, while a remarkable improvement could also be expected in low frequency range, especially for complex structures. Such approach was approved as one reliable engineering method for solving dynamic response of periodic structures.

Abstract: An experimental study was made of the mechanical properties of large scale confined concrete subjected to the axial compression test. Eleven tied concrete columns and six plain concrete prisms were tested. In the test, each specimen had the same transverse reinforcement configuration, and similar volumetric ratio of lateral steel, while different size. The test results in this paper indicate that the size of the specimen has no obvious relationship with the ultimate strength, however, it does affect the post-peak ductility to some extent. As a supplement to the experimental study, a finite element method was adopted to imitate the mechanical behavior of the confined concrete under axial compression. The results of the imitation in this paper indicate the confinement mechanism of large scale specimens.

Abstract: Various return oil channels of a large self-dumping truck hydraulic tank don’t work synchronously brings the exit temperature fluctuations, traditional heat balance calculation can’t get some point temperature in tank, so it can’t be used to analyze temperature fluctuations. Selecting RNG k-εturbulent model and using CFD method，this paper analyzes flow field in the hydraulic tank of a certain large self-dumping truck at first, then according the principle of enhancing heat exchange, proposes two structure improved schemes, and contrasts the simulation result of two schemes, The results show that the two improved schemes reduce the tank exit temperature fluctuations and the high local temperature at different degrees, and the temperature fluctuations reduce range of the best scheme is 86.51% when the initial hydraulic oil temperature is 40°C.

Abstract: In the complex conversion analysis of multi-degrees of freedom，large calculation count needed in each calculation step of Genetic Algorithm limits the running speed of genetic algorithm. So the positive calculation count to be reduced is an effective method to enlarge the range of GA’s application. Empirical Genetic-Simplex Algorithm (EGSA) proposed in this paper is one of the effective methods to solve the problem. This method is applied to structural physical parameters identification based on the structural dynamic response. The result shows that EGSA has many advantages on precision, efficiency in searching, strong to resist the noise, and good adaptation to the incomplete information.

Abstract: In this paper a dynamical equation about vibratory drum - soil system was set based on the non-linear character of vibration compaction of vibratory roller. The finite element model of vibratory drum - soil system was established by the finite element software ABAQUS, with which the vibration compaction process of vibratory drum is simulated. According to the analysis of the vibration propagation on the soil surface, the longitudinal vibration propagation of soil, the stress and strain of the soil under the vibratory drum, results have proved that it is valid to simulate the interaction between vibratory drum and soil by the nonlinear finite element method, which offered a new way to research the interaction between vibratory drum and soil.

Abstract: In order to improve the ultimate bearing capacity, In this paper, the theory of functionally graded material is introduced. This paper simulate thick-walled cylinder with functionally graded characteristics through the analysis of using different reinforced ways along the radial direction. The author analyzes the stress state of the thick-walled cylinder with plain concrete and three different reinforced ways under the radical uniform load. Comparisons and evaluations are provided based on ANSYS results. The paper provide a reasonable reinforced way that is a larger reinforcement ratio near the outer and a smaller reinforcement ratio near the inner and is different with the traditional way. But the worst reinforcement arrangement is that a larger reinforcement ratio near the inner and a smaller reinforcement ratio near the outer. The conclusion shows that the principle that larger reinforcement ratio should be adopted where the tangential stress is larger is not suitable to the thick-walled cylinder.

Abstract: To replicate the scene of bridge collapse realistically, accurately and completely, this paper proposes a scene simulation method of bridge collapse based Finite Element (FE) analysis. On the basis of suitable scene model of bridge, 3D animation of bridge collapse is implemented by the callback of graphics engine Open Scene Graph (OSG) and special effects of bridge collapse are also created by physics engine physX. In addition, terrain and surroundings are added into the scene simulation. The collapse animation proves to be consistent with FE simulation by comparison and the scene simulation is more realistic and complete due to the special effects and the rich scene. This study provides an important reference for analysis of collapse accidents of bridges.

Abstract: In order to obtain the heterogeneity of coal, the mechanical tests were performed. The experimental results show that the heterogeneity of the mechanical parameters for coal follow the Weibull distribution. Then the model of coupled gas flow and deformation process for heterogeneous coal was presented and the effects of heterogeneity of coal on gas flow and failure of coal were investigated. The finding is that the effect of the heterogeneity of coal on gas flow and mechanical failure of coal can be considered by the model in this paper. Failure of coal has a great effect on gas flow.