Applied Mechanics and Materials Vols. 580-583

Abstract: Gemorphological type is the important factor influencing the downburst wind profile. In this thesis, firstly we determine four categories of landform types under the criteria of roughness. The CFD pre-processing software GAMBIT was used to build considering the landscape type's downburst CFD computational model. Then, the established CFD computational model was imported to the calculated hydrodynamics software FLUENT to take the numerical simulation of the downburst under different landforms. Finally, in allusion to the numerical simulation result, make the research of the wind characteristics.

Abstract: Based on material mechanics theory that loads-internal force-deformation relationship of rod, this paper establish elastic foundation beam model, and establish loads-internal force-deformation differential equation of piles and columns, and identified boundary conditions according to mechanical analysis of piles and columns, Based on the boundary conditions, deformation coordination and internal force equilibrium conditions, solving differential equations, then obtain column - pile components’ internal forces. This method has good mechanical model support, and using mathematical computing software can derive the analytical expressions.

Abstract: The basic thinking, basic assumptions and basic formula system of duality disturbance theory are given in this paper. The theoretical and practical implications of duality disturbance theory are analyzed. The principles of the method of selecting the Stress-Strain relationships of relative non-disturbance material and relative complete disturbance material are given.

Abstract: Numerical simulations on thermocapillary convection of low Pr number molten tin under uniform magnetic field have been conducted under microgravity. The Navier-Stokes equations coupled with the energy conservation equation are solved on a staggered grid, and the free surface is captured by using the level set method. The present results show that the transverse uniform magnetic field can restrain the thermocapillary convection, and the fluid velocity at the hot corner fluctuates with a constant frequency at the steady state.

Abstract: The numerical-analytical solution of the non-axisymmetric problem of moisture-elasticity for hollow cylindrical soil massive is provided. We consider the steady-state water transfer. Inhomogeneity of the array due to the dependence of the deformation modulus on the soil moisture. Stress state of the array caused by forced deformations and uneven pressure rebuff of the soil. The method for solving non-axisymmetric problems with radial inhomogeneity in polar coordinates is described. Diagrams on the stress fields in homogeneous and inhomogeneous formulations of the problem are provided. In the paper made a comparative assessment of the impact on the stress state of the power factors and inhomogeneity of the soil

Abstract: The article studies the energy method for determining loss factor due to hysteretic damping in systems of vibration and seismic isolation. Typical measure of damping is, where φ is the phase angle between stress and strain sinusoids [1], or damping constant δ ( [2, 3]). Both of these parameters are acquired through experimental investigations for each type of boundary conditions or element’s cross section. Proposed energy method is capable of loss factor ψ determination for different types of beams based on only one experimental investigation. This method is used in the paper to determine the damping ratio of elastic element in vibration isolation system of precision equipment.

Abstract: In the field of geotechnical engineering, a numerical simulation model is established by meshing a three-dimensional geological model, which is composed of many seamlessly connected blocks. Each block is enclosed with constrained, triangulated boundary surfaces and called as a constrained block. Due to the complexity of geological structures, a three-dimensional geological model is very complicated in most cases, and will be very difficult to decompose this kind of model into hexahedral mesh by those commonly-used methodologies. Thus, we propose a new mesh generation method which is special for blocks with constrained, triangulated boundary surfaces: hexahedron-dominant mesh generation based on templates (HMGT). In this method, several regular blocks including cuboids, prism, pyramid, tetrahedron, cylinder and their combinations, are decomposed into hexahedron-dominant meshes that serve as mesh templates. Then, a constrained block is abstracted into a simple block, and the simple block is divided into two parts by shrinking: the crust and core. Next, a mesh template of regular blocks or their combinations is selected and mapped to the core of the simple block, and the crust of which is filled with pyramids and tetrahedra in order to obtain the subdivision of the simple block. Finally, the mesh of a simple block is directly mapped to the original constrained block to generate target hexahedron-dominant mesh.

Abstract: A high precision structured-based finite volume model for numerical simulation of dam-and dyke-breach flow was proposed. The model regarded the fully two-dimensional shallow water equations as the governing equations, and used the Godunov-type finite volume shock-capturing schemes HLLC to calculate flow flux. Its spatial and temporal accuracy were improved to two order accuracy using the slop limiter and predict-correct method, and the slope source terms and friction source terms were treated with central difference scheme and fully implicit method respectively. And then a robust procedure was adapted in the model to efficiently and accurately simulate the movement of wet and dry boundary and a method of high calculation efficiency was applied in the treatment of complex boundary. A popular example was used to validate the capability of the model. The result shows that the model can capture flow processes over irregular boundary accurately and shows good stability and accuracy.

Abstract: Systems of ODEs arising from transient structural dynamics generally exhibit high-frequency/low-frequency and linear/nonlinear behaviours of subsets of state variables. This paper resorts to the use of different time integrators with different time steps for subsystems, to tailor each method and its time step to the solution behaviour of the corresponding subsystem. Anovel partitioned integration method with the acceleration continuity is proposed whose velocity continuity is also ensured by means of the mass projection strategy. Both its stability and accuracy properties are examined through numerical analysis on Single-DoF split mass system.

Abstract: Limit bearing capacity of foundation soil was studied in the paper using slip line method. Slip line results are found to be consistent with the results calculated by Terzaghi theoretical formula and Hansen theoretical formula. Then the influence of factors such as cohesion and friction angle is studied under complete smooth or complete tough conditions. The results show that in a certain range, limit bearing capacity of foundation increases with the increase of C₀, Φ. Limit bearing capacity of foundation under complete smooth condition is lower than the complete tough one.