Advanced Materials Research Vols. 594-597

Abstract: Pin coupling is widely used in engineering structures and its local strength analysis is an important item during design. The methods to calculate joints in pin coupling of beam structures are presented and analysis, then the finite element modeling and the whole calculating process of beam structures with pin coupling are discussed. The concentrated forces under pin roll are transformed into equivalent pressure and the expressions of the equivalent linear and cosine pressure function are derived. The example’s results show that the finite element solutions of the two equivalent pressure functions are similar and these equivalent pressure functions can be used for engineering calculation of joints in pin coupling of beam structures.

Abstract: Abstract: Cylindrical shells are widely used in civil engineering. Examples include cooling towers, nuclear containment vessels, metal silos and tanks for storage of bulk solids and liquids, and pressure vessels. Cylindrical shells subjected to non-uniform wind pressure display different buckling behaviours from those of cylinders under uniform external pressure. At different aspect ratios, quite complex buckling modes occur. The geometric nonlinearity may have a significant effect on the buckling behavior. This paper presents a widely study of the nonlinear buckling behavior of cylindrical shells of uniform thickness under wind loading. The finite element analyses indicate that for stocky cylinders, the nonlinear buckling modes are the circumferential compression buckling mode, which is similar to cylinders under uniform external pressure, while for cylinders in mediate length, pre-buckling ovalization of the cross-section has an important influence on the buckling strength.

Abstract: Based on Biot’s elastodynamic theory for poroelastic media, the dynamic response of a poroelastic half-space due to a time-harmonic concentrated vertical load applied at the free surface is investigated. Different from previous treatments of the free surface as either fully permeable or fully impermeable, the free surface of a pororelastic half-space is treated in this study as a more realistic semi-permeable boundary condition, i.e. the permeability of the free surface is considered. The governing equation for axisymmetric motion of a poroelastic half-space is solved by applying the Hankel integral transform. Numerical results are presented to show the effects of semi-permeable boundary condition on the dynamic response of poroelastic half-space.

Abstract: Abstract. This paper presents a new type of adjustable mixing equipment, and the internal flow field of the adjustable mixer have been studied by using the model of LES(Large eddy simulation),and the pressure loss, the speed change and vortex scale have been studied. In conclusion, along with blades angle and number increases, the flow resistance increases violently, so the range of blade rotating angle should be controlled within 30 degrees. As the depth of the pipeline velocity is increasingly large, large velocity gradient is contributed to the collisions between the colloidal particles. In pre-mixed, the vortex effect of the pipeline highly enhances the vortex diffusion, and improves the mixing efficiency. The vortex strength will be reinforced and dimension will be reduced, with the vanes cutting the flow, which can help flocculation.

Abstract: In order to monitor and control the effect of blasting vibration on dam body, spillway overflow surface and mechanical and electrical equipment foundation at the excavation of resistance sliding key chamber, the fixed monitoring point scheme was used to monitor vibration speed of each point. According to the construction progress, a total of 44 times blasting vibration test were carried on, and data are integrity, which can accurately reflect the effect of resistance sliding key chamber excavation blasting on adjacent buildings. In blasting construction process, according to the analysis of monitoring data, the explosive dosage of single stage was adjusted, which effectively control the effect of blasting vibration. The results indicate that, in the process of resistance sliding key chamber blasting construction, particle vibration velocities of adjacent buildings such as dam body, spillway overflow surface, mechanical and electrical equipment foundation and etc. are in the velocity range of security vibration, which meets the requirements of design and specification, and real-time analysis of field monitoring guarantees the smooth completion of site construction.

Abstract: In this paper, a model of coupled van der Pol-Duffing oscillators with delays is studied. Two sufficient conditions to guarantee the existence of oscillations for the system are provided. Numerical simulation is given to demonstrate our result.

Abstract: Vibration mitigation of slender cables using the non-obstructive particle damping technology was investigated by the free vibration experiments for the NOPD steel wire. The increased cable modal damping ratios attributed to NOPD were measured and analyzed. The influences of factors such as particle filling ratio, particle mass ratio and initial deviation displacement on the damping effect are discussed by means of test data. Test results demonstrate that the particle filling with a suitable filling ratio or mass ratio to the cable can significantly improve the damping of the cable. Either particle filling ratio or mass ratio is a principal influencing factor for the damping effect of the cable. Under the same particle filling ratio and tube diameter, the larger initial deviation displacement is generally advantageous to the damping effect of wire, especially at the suitable particle filling ratio.

Abstract: It is necessary to control the noise and vibration with a high frequency caused by various trains, not only nearby the railway, but also in the station area. An innovative rail-damper was fabricated and evaluated for its effectiveness in vibration control and noise suppressing. From a long-term monitoring, rail-damper can reduce effectively the vibration and noise acceleration level, both along tracks and in platform. The results indicated that as the track was masked by the rail-damper, the train noise equivalent sound level can be reduced more than 3.6 dB, and the vibration acceleration level could be reduced by an average of 6.7dB. For the vibration of the platform, the acceleration level was reduced by an average of 9.3dB. The rail- dampers can preferentially reduce the high-frequency part of the site vibration. The study herein would be useful to understand the feasibility of rail-damper for the noise and vibration control for the railway engineering.

Abstract: Analysis was carried out for dynamic responses on a continuous bridge under normal traffic flow. The inspection, testing and analysis for the tested bridge mainly consist of the measurement of pavement roughness and analysis on power spectral density, the testing and analysis on natural vibration characteristics, the observation of traffic loads under normal traffic flow and the corresponding measurements of dynamic displacement and acceleration on bridge. To determine impact factors in terms of measured dynamic displacement responses, low pass Butterworth filter is used for filtering the dynamic part of measured dynamic displacement and the static extreme values are reserved. And then，the distribution fit test is performed using K-S methodology for measured impact factors according to Extreme-I type respectively. Finally, the impact factor of this bridge, which is determined based on statistical method, is compared with code-specified impact factors of different countries.

Abstract: With the rising of single-machine capacity ,the structure of turbine generator units has become increasingly complex, and mechanical failure problem has been rapidly concerned among engineers. This paper develops a fault tree in vibration for turbine generator units by analyzing failure cause, which regard rotatable part as a group. In this study, the feature of failure is summarized to realize the whole system, and an example is examined at the end of paper. Through the qualitative and quantitative analysis shows that, the failures of turbine generator units are complicated and correlative, the vibration of rotatable parts is the most important factor affecting the stable of turbine generator units, and system reliability is associate with the structure of fault tree and the probability of basic events .