Advanced Materials Research Vols. 774-776

Abstract: The mechanical model of the electro-rheological fluid damping adjustable isolator is established. Then the two degree of freedom vibration adjusting system of engine and car frame is built. The PD fuzzy control method is used to control the damping characteristic of the damping adjustable isolator. Simulation analysis is executed by using Matlab software. The datum of simulation analysis indicates that the isolation capability of the PD fuzzy control electro-rheological fluid damping adjustable isolator is well.

Abstract: With the limit equilibrium method for the rigid body, this paper deduces a three-dimensional analysis method for the stability against sliding of concrete dam on rock foundations with mud layers on the basis of the stability against sliding of wedge. The engineering practices show that it is economical and reasonable to apply the method given here to the analysis for the stability of concrete dam foundation with mud layers in the case that the dam axis being not parallel to the strike of mud layers.

Abstract: A polyurethane-based magnetorheological elastomer (MR elastomer) was designed, and the magnetorheological effect (MR effect) under shear mode was systematically tested by the designed test set. The results show that the relative MR effect increases with the exterior magnetic filed strength and decreases as the incentive amplitudes increasing. The preload displacement also directly determines the relative MR effect and too large deformation will make the MR effect decreased sharply. But the incentive frequency has no very obviously influence on the relative MR effect.

Abstract: The numerical calculation models of the high-speed train in the straight and different radius curve railway are established. Author calculated transverse forces (moments) acting on the three sections (first train, middle train and rear train). At the same time, under with the shelter wind wall and without the wall, the change trends of side forces coefficients and rolling moments coefficients of trains with the train speed and the transverse wind speed are analyzed. Results show that, in the straight railway and curve railway, transverse loads coefficients increase with the increase of the transverse wind speed and decrease with the increase of the train speed. The transverse forces (moments) of the three sections of the train with the shelter wind wall are opposite to that without the wall. Traffic safety under crosswinds focuses on the rear train with the shelter wind wall and focuses on the first train without the wall. At the same train speed and transverse wind speed, side forces and rolling moments of trains in curve railway is greater than that of trains in straight railway. Absolute values of transverse loads coefficients decreased gradually with the increase of the radius of the curve, and their relationship basically is the linear relation.

Abstract: The main hazards caused by blasting include vibration, flyrock, air shock wave, noise and dust. And the blasting flyrock is one of the dangerous factors to surrounding environment. Small and medium open pits are usually surrounded with residential districts, so controlling the casting distance of flyrock is very important. It is difficult to predict the casting direction and flying distance of blasting flyrock because of its more influence factors. Based on Sihe stope of Fangmayu Iron Mine, the paper analyses the causes, movement rule and casting direction of the bottom flyrock of open pit caused by bench blasting, calculates the casting distance of bottom flyrock, obtains the actual casting initial velocity and the biggest safe distance of blasting flyrock in Sihe stope. The study results can provide references for reducing the flyrock harzards of open pit caused by bench blasting.

Abstract: With the development of economy and technology, many long span bridges have been constructed. However, oversize thickness and long duration of snow on these long span bridges might lead to security issues. The computational fluid dynamics software FLUENT is employed to simulate the snow effect on the bridges. According to the two-phase fluid theory, the relationship between air phase and snow phase is one-way coupling. The corresponding changes of snow load on the bridge deck under the action of strong winds are studied in this paper and the comparative analysis about aerodynamic impacts before and after the snow are conducted as well. According to the results, the snow has notable influence on the aerodynamic characteristics of bridge decks. Keywords: computational fluid dynamics; two-phase fluid theory; snow load; aerodynamics;

Abstract: As long span suspension bridges have high towers, large flexibility and low damping, it is a must to consider the wind-resistant stability in bridge designs, especially for sea-crossing bridges where there are always strong winds. To ensure the traffic safety under strong winds, wind screens are often installed on the bridge deck to reduce the wind speed over the roadway. In order to analyze the influence of wind screens on wind-resistant capability and driving security for long span suspension bridges, CFD wind tunnel technique is adopted to analyze the flutter stability, the buffeting displacement and the wind environment of the bridge deck with and without wind screens. According to the analysis, the installation of wind screens could effectively reduce the wind speed over the roadway, but it would also weaken the wind-resistant capability of the bridge. The analysis results could be used as reference for the wind-resistant capability optimization and the wind screen design for long span suspension bridges.

Abstract: The article analyzed the modal of disc brake, the intrinsic characteristics of each disc brake parts were obtained, using modal tests to verify the accuracy of the numerical simulation method; by comparing different vibration mode and natural frequency of the brake parts, predicting the frequency which vibration may occur, aiming at resonance frequency which is easy to occur, improving the structure of the disc brake to improve each order natural frequency, the resonance of the disc brake is effectively reduced, the braking noise was decreased, The study laid a foundation for vibration and noise control of the disc brake.

Abstract: The blade frequency noise of non-cavitation propellers in an non-uniform flow is analyzed in time domain. The unsteady loading (dipole source) on the blade surface is calculated by a potential-based panel method. Through calculation and comparison, the noise attenuation trend of propeller is discussed. The noise decays more quickly in the near field than in the far field. The Attenuation Trend of the Propeller Noise

Abstract: Based on experimental results of uniaxial compression and short-term creep using 8-step loading-unloading method, fine sandstone specimen, which lower creep limit is 27MPa, present typical brittle breakage properties of hard rock. The correlative coefficients of linear regression function for isochronous stress-strain curve are all higher than 0. 92, and the ratio of long-term strength to instantaneous strength reaches 94. 39%，which indicate that the whole creep of fine sandstone specimen is weak. The average correlative coefficients of linear regression function for isochronous stress- axial strain curve are 3. 92% higher than that of average correlative coefficients of linear regression function for isochronous stress- radial strain curve, so nonlinear creep property of the fine sandstone specimen in axial direction is correspondingly weaker than that in radial direction. Negative Gauss distribution can be applied collectively to nonlinear creep of fine sandstone specimen, which has obvious time effect.With increasing loading, the reduction degrees of average correlative coefficients of linear fitting functions of isochronous stress-axial strain curve and isochronous stress-radial strain curve are 0. 97% and 0. 67% respectively, which indicates the linear correlation decreases commonly. Thus, the degree of nonlinear creep for fine sandstone specimen increases along with loading stress with obvious stress effect.