Advanced Materials Research Vols. 1065-1069

Abstract: Multi-scale theory and framework in research of fatigue crack is described, and then in meso-scale the simulation model of polycrystalline material grains is established using Voronoi algorithm, and the feasibility of this algorithm is verified at the same time; cohesive zone method is introduced and cohesive strength on the interface along grain boundaries is discussed, then Young´s modulus is tried to define in meso-scale according to cohesive zone method, which prepares the calculation of the finite element model.

Abstract: The finite element model was established in this paper to study the process of dynamic response of RC frame structure under internal explosive loading. The burst point in the model was located in the center of the frame structure .The article analyzed the process of the dynamic response of the frame structure in the explosive environment and the result of the numerical simulation accorded well with the test. The result showed that the finite element model was feasible as well as providesed reference to the design and protection for the building structure.

Abstract: Rectangular steel truss Y-connections, whose chord is filled in concrete, is described. The behavior of Y-connections include hollow structural section and concrete-filled section loaded in tension is analyzed by means of finite element analysis. It is shown that there is a significant improvement in strength and stiffness of Y-connections with concrete-filled chord.

Abstract: The most widely used multi-axial concrete models including elastic-plastic model and elastic plastic damage model are expounded and it is recognized that the elastic plastic damage model is more reasonable to reflect nonlinear characteristic of concrete. The development and application of elastic plastic damage model is comprehensively appraised and a practical elastic plastic damage constitutive model is established. Finally the dynamic trend of constitutive model of concrete development is introduced.

Abstract: The stability and dynamics of the two-dimensional elastic plate with simply supported boundary conditions in uniform axial subsonic flow were studied. The governing equations of coupled elastic plate in axial flow were derived based on the potential theory. The finite difference method was employed to discrete the governing equation and the flow potential function. The governing equation can be expressed as the function of structural transverse vibration displacement by the matrix operations. The eigenvalue method was used to analyze the stability of the elastic plate, the results of which show that the models with simply supported boundary conditions undergo divergent instability when flow velocity reaches the critical value, the critical divergence velocity is in close agreement with theoretical result using other analytical approaches.

Abstract: How to truncate stress wave is an important problem that must be considered in design of engineering structure. As an effective detection method of stress distribution, the dynamic photoelasticity has been wide used in stress analysis, such as detection of mechanical structure, civil engineering and water conservancy etc. In this paper, the stress wave isochromatic fringe at different interface structure has been obtained through vertical shooting experiment. The structural stress wave propagation rule of three kinds of case is studied by comparison fringe pattern. The experimental research results show that the stress wave propagation can be effectively guided to a fixed direction through installed connecting parts in structural connection position and the method can avoid integrity damage of structure caused by local large stress changes. Finally, the dynamic photoelasticity is an intuitive and effective way to study stress wave truncation problem.

Abstract: In order to establish the virtual design method of shaking table test of structure in sine-swept vibration, the accurate sine-swept function in logarithmic variety is proposed by theoretic derivation. According to the numerical simulation, the dynamic response of structure in sine-swept vibration by multi-support excitation is acquired. And the maximum amplitude is less than that of structure in sine-swept vibration by single-support excitation based on the comparison with each other. However, several orders vibration mode are excited by the sine-swept vibration in multi-support excitation, and the structure resonates many times, which will increase the damage probability of structure. In other words, the load case of sine-swept vibration by multi-support excitation is worse than the case of sine-swept vibration by single support excitation. The conclusions above can provide basis for design and dynamic time-domain analysis of aerospace products of shaking table test in sine-swept excitation.

Abstract: A numerical study was conducted to examine the flow field around and heat transfer from an elliptical cylinder of AR=0.5 in two types of the annular boundary and rectangular one. The fluid near the surface separates from the cylinder surface and forms a steady recirculation bubble at the rear end of the cylinder at the first critical Reynolds (Rec1). The vortices begins the alternating separation at the second critical Reynolds (Rec2). Rec1 and Rec2 for the fluid in two boundary types are studied. The Nusselt numbers are compared at Rec1 and Rec2 respectively.

Abstract: Based on many of researches about bend of beam under uniform load in the Hamiltonian system, but few on bend of beam under the force couple with load and the thermal, according to the validity of Hamiltonian method in symplectic space, in this paper, the method is used to solve bending of plane beam under the force couple with load and the thermal, and give out the distribution of displacement under this condition. Numerical simulations show the effect of temperature has great influence on the distribution of displacement of the beam. The results provide a numerical model and reliable reference data for the follow-up study of its analytical solution.

Abstract: Mine cooling system plays an important role in the high temperature mine. The installed position of the air condensers in the intake airway has great influence on the cooling efficiency and effectiveness of coal face. According to the concept of the air cooling length, we mainly study the effective installation position of the mine air condensers in the intake airway and put forward the installed position determination method of more groups of air condensers. Through the average calculation method, the ideal installed position of the air condensers is determined. Thus the efficiency of the mine cooling system is improved, and the safety and high efficiency of the mine production is ensured.