Applied Mechanics and Materials Vols. 670-671

Abstract: The distinctive paper is devoted to new defect identification methodology based on dynamic characteristics of real construction. The methodology is founded on mathematically formalized procedure of FE-model adaptation by measured and calculated eigen pairs of dynamic system. Main steps of the methodology are described. Application of the methodology together with standing wave method might allow to identify deviations of stiffness parameters of a real construction facility.

Abstract: The distinctive paper is devoted to approbation of new defect identification methodology based on the dynamic characteristics of real construction. Mathematically formalized procedure of the methodology is implemented at the test bench. The proposed algorithm identifies a defect. The features of results obtained from the procedure are described.

Abstract: For indepth study on flow characteristics for fluid bypass obstacles in micro-channel, the Lattice Boltzmann Method (LBM) was used to simulate fluid flow over two circular cylinders in side-by-side arrangement of a micro-channel. The velocity distribution and recirculation zone length under different Reynolds numbers (Re = 0~100) and different spacing ratio (H/D= 0~2.0) were obtained. The results show that the pattern of flow and the size of recirculation zone in the micro-channel depend on the combined effect of Re and H/D.

Abstract: The transient vortex structure evolution process of two-dimensional flow in a driven square cavity with one moving end was studied. The time curves of flow field variables, the flow patterns of different specific moments and the required times of flow field from static to statistical steady state were comparatively analyzed for different Reynolds numbers. Transient simulating results show that the nascent vortices always appear near the boundaries in the initial driving stage, then gradually move away from the boundaries to form a large vortex almost occupying entire cavity and two secondary vortices in left and right corners of the cavity bottom. The greater the Reynolds numbers, the longer the required times of the flow field reaching by the statistical steady state, also, the more complex of the vortex structure evolution.

Abstract: This paper studied the difference between the segment loading static analysis method and the uniform loading static analysis method on the mobile refuge chamber. The structure strength static analysis of the mobile refuge chamber was made in the uniform and segment loading ways by the finite element software SolidWorks Simulation. The stress cloud charts and the displacement cloud charts were obtained. The comparison result indicates that the results of the segment loads method are less than those of the uniform loading method and is closer to those of the dynamic analysis method. Therefore the segment loading static analysis method is better than the uniform loading one.

Abstract: Some inclined boreholes have to be drilled in directional wells, but the track of inclined borehole is impossible to be a ideal straight line, there are always some geometric defects such as bending, thus the drilling string in it is bound to have initial bending due to the constraints of borehole, hence the drilling string in inclined borehole is usually a curved compressed rod. Its buckling nature is quite different from straight compressed rod, it is necessary to analyze it specially. In this paper the buckling problem of drill string in inclined borehole with a concave curved geometric defect is studied by energy method, the computing formula of buckling load for it was obtained. And the influence of initial concave bending on buckling load was discussed. The research indicates that when drilling string in inclined well bore has a initial concave bending, the greater the degree of initial bending of drill string, the greater its buckling load.

Abstract: This article suggests methods of calculations of buildings and structures responsible for specific effects on the basis of nonlinear dynamic methods. Example of calculations wide-span structures in the time domain by direct integration of equations of motion, taking into account the nonlinear nature of the structures.

Abstract: The water droplet erosion protection of the rotor blades has been an important issue for a long time, regardless of the design. The aim of this paper is to present a aerodynamic design method for decrease risk of water droplet erosion in wet steam turbine, as well as to present the comparison between then five diffrent bow stator blades. This paper also presents numerical investigation of three dimensional wet steam flows in a stage. This stage has long transonic blades designed using recent aerodynamic and mechanical design methods. The results show that, the one of the five diffrent bow stator blades decrease rist of water droplet erosion of rotaional blades, and the change of the efficiency is small.

Abstract: Using the method of numerical simulations to study fluid dynamic characteristic of underwater vehicle rotary motion, using the N-S equation turbulence model description of the steady rotation of the vehicle, this paper studies the numerical calculation method of aircraft rotating derivative underwater, using UDF programming to produce a stable pressure rotation the flow field, set up an numerical turning basin. Then based on the simulation analysis the influence of the different radius of gyration and different angle of attack on the vehicle motion.

Abstract: In this paper, strength analysis of the sub-frame of a heavy-duty dump truck was done based on ADAMS and ANSYS. A prototype model of dump system of dump truck was built basis of drawings and technical documents. The prototype model of dump system was imported into ADAMS, then driving and kinematic pair were created to form a complete prototype system. Force curve and force value of each key point in the sub-frame was obtained under unloaded condition by simulation of unloading operation. The results showed that the strength and stiffness of the sub-frame under pure bending condition and the initial stage of unloaded condition meet the requirements;In critical slipped stage of cargo, the maximum stress of the rear rotating shaft of sub-frame is greater than the yield limit of the materials, and its position is consistent with fault location in the practical application.