Applied Mechanics and Materials Vol. 274

Abstract: Based on finite volume method of finite element method, the aerodynamics models of the train passing through bridge noise barriers (high respectively, for 2.15m, 1.93m) and the subgrade (high respectively, for 2.95m,3.95m) noise barriers is established by large commercial fluid dynamics calculation software. The three dimensional transient outflow field is numerical simulated by applying dynamic mesh technology and large eddy simulation method (LES) for the train passing through noise barriers. The extreme value, schedule curve and pressure cloud contour of fluctuating wind pressures of the different height noise barriers on bridge and roadbed are acquired for 300 ~ 420 km/h different speeds. Extreme values of fluctuating wind pressures product by trains with different speeds are contrast analyzed. The simulation results are very close to the experimental data, proves the validity and feasibility of the finite element model and the accuracy of the parameters. This research provides the theory support to the structural design of the noise barriers and can effectively guide the structural design of the noise barriers.

Abstract: There is often more than one failure at the same time when NC machine tools fails, but only one failure data is recorded which leads to that the reliability model of NC machine tools is not rational. In addition, the assumption of “repaired as good as new” for NC machine tools which consists of hydraulic, mechanic and other complicated subsystems is questionable and unreasonable. In this paper a method of reliability modeling using Blocksim and Weibull++ for NC machine tools is proposed. In the end, one example is provided and examined to show its potential applications and benefits. The result shows that the method of reliability modeling is more scientific and more in line with the practice.

Abstract: As natural phenomena, financial and securities markets are full of unpredictable changes. It is an interesting topic whether fluctuation of stock prices follows certain rules. This paper sources data from the stock market of Taiwan, and selects the stock of Uni-President Enterprises Corp. which is a representative stock with large capital share, and belongs to an traditional industry that is not affected by business cycles, and selects the stock of TSMC which is a representative stock with large capital share, and belongs to an technology industry that is easily affected by business cycles. This paper will use the Fractal theory to study the accuracy of prediction of the random stock price of these two industries.

Abstract: This work describes a simulation research concerning dynamic effect of multi-pad hydrostatic thrust bearing having rectangular recess, sector recess, ellipse recess and I-shaped recess in order to solve the loading capacity of the hydrostatic thrust bearing. Three-dimensional pressure field of gap fluid between the rotation worktable and the base has been computed by using the Finite Volume Method. This study theoretically analyzes the influence of recess shape on dynamic effect of the bearing according to computational fluid dynamics and lubricating theory, and the simulation results indicate that an improved characteristic will be affected by recess shape easily. Through this method, the safety of a multi-pad hydrostatic thrust bearing having different cavities can be forecasted, and the optimal loading capacity of such products can be achieved, so it can provide reasonable data for design, lubrication, experience and thermal deformation computation for hydrostatic thrust bearing.

Abstract: Abstract. As a new material ,CRYSTOE and NEOPARIES are widely used in aerospace and military equipment, its surface quality requirements is very high. CRYSTOE and NEOPARIES disc convex machining has done a lot of trials. And analyzed the experimental data by using Orthogonal test method get the optimal processing parameters. It also provide a reference for future processing tests.

Abstract: In order to obtain approximate solution of natural frequencies for the free vibration of anisotropic circular cylindrical shells made of GFRP (glass fiber-reinforced plastic) with asymmetric boundary conditions, Love’s theory and energy method are used. Computation results show that the fundamental natural frequency comes from different vibration modes while the winding angle varies, the effect of number of axial half waves is stronger than number of circumferential waves on natural frequency of free vibration of anisotropic circular cylindrical shell. The effect of shell’s geometrical parameters is also investigated on natural frequencies.

Abstract: After data preprocessing,the autoregressive(AR) bispectrum diagonal slices were figured and fractal box dimensions were calculated. The results show that the box dimensions are different in evidence under different conditions. So the fault pattern recognitions of the relief valve are effective by the method of using fractal box dimension of AR bispectrum diagonal slices, it provides a simple and accurate method for fault diagnosis of the relief valve.

Abstract: Authors have presented a new procedure as gas-liquid combined multiple cut. In order to acquire the best machining quality and the greatest efficiency, it is necessary to analyze the WEDM process with multiple performance characteristics including machining time and surface roughness and to optimize some processing parameters such as pulse duration, pulse interval, peak current, main power supply voltage, servo feed, offset and servo voltage. The orthogonal experiment is designed to reveal the relationship among the parameters, the gray relevance theory is used to optimize the processing parameters under the multiple process index of the LS-WEDM in gas, namely optimizing the process parameters under the surface roughness and machining time, and the optimized process parameters can be obtained from gray relation grade.

Abstract: In this paper, the dynamical stability analysis of anisotropic cylindrical shells under uniformly distributed periodic extensional axial force is presented, while the winding angle varies. Fiberglass reinforced plastic is considered as a homogeneous solid anisotropic material. The shell’s elastic properties depend on the winding angle of fiberglass. The effect of the winding angle on the critical axial force is investigated. The intervals of winding angles at which the parametrically unstable vibration happen are determined

Abstract: In order to increase the working performance of a heavy constant flow hydrostatic center rest, a theoretical study concerning the lubricating oil film dynamic pressure effect of the heavy constant flow hydrostatic center rest is described. The Computational Fluid Dynamics and the Finite Volume Method have been used to compute numerically the static pressure field and the total pressure field of the lubricating oil film. The influences of spindle rotating rate, lubricating oil dynamic viscosity and inlet flow rate on the lubricating oil film dynamic pressure effect of the heavy constant flow hydrostatic center rest were analyzed based on the computational fluid dynamics and lubrication theory, and the influencing laws were revealed. By means of this method, the reasonable data can be provided for reasonably controlling dynamic pressure and structure optimal design of the heavy constant flow hydrostatic center rest.