Based on the train-track coupling dynamics and high-speed train aerodynamics, this paper deals with an improved algorithm for fluid-structure interaction of high-speed trains. In the algorithm, the data communication between fluid solver and structure solver is avoided by inserting the program of train-track coupling dynamics into fluid dynamics program, and the relaxation factor concerning the load boundary of the fluid-structure interface is introduced to improve the fluctuation and convergence of aerodynamic forces. With this method, the fluid-structure dynamics of a high-speed train are simulated under the condition that the velocity of crosswind is 13.8 m/s and the train speed is 350 km/h. When the relaxation factor equals 0.5, the fluctuation of aerodynamic forces is lower and its convergence is faster than in other cases. The side force and lateral displacement of the head train are compared between off-line simulation and co-simulation. Simulation results show that the fluid-structure interaction has a significant influence on the aerodynamics and attitude of the head train under crosswind conditions. In addition, the security indexes of the head train worsen after the fluid-structure interaction calculation. Therefore, the fluid-structure interaction calculation is necessary for high-speed trains.
To analyze the bending properties of GCr15 steel guide rail based on the elastic-plastic theory, the novel bending loading
method consisting of multi-step loading and corresponding unloading was applied in three specimens with different cross section
shape and different heat treatment condition. According to the experimental results, using numerical calculation software
program and the numerical simulation with finite element analysis (FEA), the relationships among the maximal load and displacement
on cross section shape with each step bend loading, the loading stroke with the heat treatment condition, and the loading
stroke with cross section shape were gained, and also those curves were discussed qualitatively. Finally, the contrast results
between the numerical simulation and experiment were carried out to study the influence about the multi-step loading on specimen.
It is put forward that enlightenment for the straightening stroke in the precision linear guide rail manufacture process. 相似文献
W-25Cu alloys were microwave sintered in a 2.45 GHz multimode applicator. The densification, microstructure and their dependence
on sintering mode and Fe addition were investigated in detail. Owing to the volumetric heating intrinsic in microwave processing,
a microstructure with larger W grain size in center regions was observed as against larger grain size in edge regions for
conventional sintering. Microwave sintering demonstrates its intrinsic advantages such as rapid heating rate, densification
enhancement and microstructural homogeneity; but it undesirably promotes W grain growth. Under microwave sintering, the role
of Fe addition on compact consolidation is not so substantial as under conventional sintering. Moreover Fe degrades the microstructural
quality, generating worse uniformity and coarser W grains. 相似文献
CuS pineal microspheres congregated from interleaving nanoflakes with thickness of 40 to 200 nm were synthesized by a pyridine-solvothermal process via the reaction between cupric chloride(CuCl2·2H2O) and thioacetamide(TAA,CH3CSNH2).The products were characterized by X-ray diffraction and scanning electron microscopy.UV-Vis absorption spectrum,excitation and photoluminescence spectra of CuS pineal microspheres were obtained at room temperature to investigate their optical properties.A possible growth mechanism on the formation of CuS pineal microspheres is proposed.The factors influencing the evolution of morphologies of CuS crystals including the dosage of the reactants,surfactant,and sulphur-source were also analyzed. 相似文献
Field measurement on wind characteristic and buffeting response of existing bridge is of great value to the development of
bridge wind engineering, and the structural health monitoring system (SHMS) employed in many long-span bridges provide a research
basis for the field measurement. In order to provide reliable basis for wind resistant evaluation of Runyang Suspension Bridge
(RSB), two anemometers and 85 accelerometers were installed in the SHMS of RSB. In August 2005, Typhoon Matsa crossed over
Jiangsu, the SHMS timely recorded the typhoon and structural vibration responses. In this paper by using the time-frequency
technique and statistical theory, the recorded data were analyzed to obtain the strong wind characteristics, the buffeting
response characteristics of the cable and deck, and the variation of buffeting response RMS versus wind speed. Results obtained
in this study can be employed to validate the credibility of current buffeting response analysis theory techniques, and provide
reference values for wind resistant evaluation of other long-span bridges.
Supported by the National Hi-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA04Z416), the
Key Project of the National Natural Science Foundation of China (Grant No. 50538020) and the Outstanding Youth Fund of the
National Natural Science Foundation of China (Grant No. 50725828) 相似文献