Applied Mechanics and Materials Vols. 543-547

Abstract: The artificial lighting level and visual comfort of drivers for a high-speed train cab are evaluated by using computer simulation technology. The simulation model is established first, and then some lighting quality indexes, such as illuminance, illuminance uniformity and glare, are analyzed based on related design standards. Considering the effects of environmental lighting on drivers physiology and psychology, the analysis on environmental psychology for driver of the cab are conducted also. The evaluation method proposed in the paper is significant for improving artificial lighting design of high-speed train cab.

Abstract: The variation rules of middle and high level atmosphere affected by sun activity are analyzed, and atmosphere resistance perturbation acceleration models of spacecraft orbit are deduced. Atmosphere resistance perturbation is simulated by STK, and the parameters of spacecraft orbit affected by atmosphere resistance are got at different situation of sun activity. Finally, the life of spacecraft orbit is calculated.

Abstract: In this paper, a 2-D numerical simulation of the wind turbine S825 airfoil is conducted with Spalart-Allmaras (SA) turbulence model at different attack angles. By comparing with experimental data, a novel method of modifying SA model is proposed. The key parameter in SA turbulence model is set with different values in the non-separating region and separating region divided by separating point respectively. This method improves the predictive accuracy of SA turbulence model when the airfoil works at stall conditions.

Abstract: The running system is the key part to finish training or battle tasks of complicated equipments. But formidable working conditions influence the measurement of load spectrums and it is difficult to analyze and forecast the reliability of running system. Actual vehicle experiments and virtual prototype are firstly combined to obtain complete load spectrum of running system. According to the materials S-N curve, stress and strain spectrums can be computed. Nominal stress method and local stress and strain method are combined with probability density accumulation damage theory to compute the probability density distribution function. Then, the reliability of running system can be forecasted, which provide adequate reference for the maintenance cycle confirmation and mission reliability prediction.

Abstract: There are coupled cases of high-cycle fatigue and low-cycle fatigue in torsion shaft of military tracked vehicles. To accurately analyze the stochastic fatigue reliability of torsion shaft, a new kind of decoupling method for high-cycle fatigue and low-cycle fatigue was firstly put forward. Probability fatigue accumulation damage theory and nominal stress method were combined to analyze high-cycle fatigue. Random response surface method was adopted to fit the life distribution function for low-cycle fatigue. To obtain the high-cycle and low-cycle stochastic fatigue reliability, probability fatigue accumulation damage theory and local stress and strain method were used. Then, composite damages of torsion shaft under high-cycle fatigue and low-cycle fatigue could be achieved based on probability fatigue accumulation damage thoery.

Abstract: The influence of sliding surface on SMC design is considered. How the sliding surface affect the chattering frequency and amplitude is investigated by describing function (DF) approach. In part-state sliding surface SMC, the chattering can be changed by feedback state selection. The relationship between chattering types and initial state values is analyzed. The proposed approach is proved has sufficient accurate estimation and judgment by simulation response curves. Simulation curves show that sliding surface design plays important roles in chattering frequency and amplitude.

Abstract: 12 kinds of automotive radiator cell models were simulated at different air inlet velocities using CFD software Fluent. The distributed drag coefficients of each cell model were obtained by least squares method. Then the whole radiator model whose fins region was replaced by the porous media was simulated. The numerical results were validated by experiments which indicate that the porous media method is reliable. The study shows that the radiator heat dissipation is significantly influenced by fin structure and the model with a fin space of 1.4mm and a louver angle of 23^o has the best cooling effect.

Abstract: Hydraulic hybrid technology of vehicle has the potential to significantly improve fuel economy and reduce emission, and increasingly aroused the attention of the research institutions and automotive manufacturers all over the world. The main of this work is to design a parallel hydraulic hybrid system for a heavy terminal tractor. Firstly, overall scheme design, construction design, and hydraulic regenerative braking system (HRBS) for terminal tractor are designed. Furthermore, the hydraulic hybrid terminal tractor is refitted successfully. The test results show that the sample vehicle is credible and in good operation, a fuel economy improvement of the new scheme is 38.1%~61.6% more than conventional baseline. Experimental study has very important value in the hydraulic hybrid terminal tractor real application.

Abstract: Vibration exciting theory of working engine was analyzed based on dynamic method. Model of engine system and mounts was established and simulated in multiple working conditions by Power Unit module of dynamics software excite. Vibration acceleration of points on engine block adjacent to each mount was extracted to characterize and evaluate the vibration excited by engine in different working condition.

Abstract: Based on the structural characteristics of a car B-pillar, the scheme of equal spacing layout on the welding spot partitions is adopted as the initial welding spots layout. The same constraints and loads are conducted on the models with different welding spot spacing. The highest strain values are calculated and analyzed around the welding spot areas. The fatigue life of the welding spot is calculated via the all-strain-life prediction model. The changing rule of the welding spot fatigue life under different spot spacing is obtained by the method of curve fitting. The optimal layout of the welding spots for the B-pillar is gotten finally. The layout is verified feasibility by comparing with that of the original model.