Applied Mechanics and Materials Vol. 470

Abstract: The processes of the fuild through the elbow pipe under different conditions are simulated by the FEM software named FLUENT. Then, the effects of varied parameters on the distribution of pressure on inner suface of elbow pipe are studied with dimensionless analysis method. Finally, a distribution model of pressure at the the minimum life section where the axial angle α is 45°, degree of curvature k=R/d, circle angle β, fluid density ρ, fluid outlet pressure P₀ and fluid velocity v is built and verified by fitting the simulation data. The research conclusion lays the groundwork for strength check and structural design of the elbow pipe

Abstract: Engineers are well aware that, due to the stochastic nature of earthquake ground motion, the information obtained from structural response analysis using scant records is quite unreliable. Thus, providing earthquake models for specific sites or areas of research and practical implementation is essential. This paper presents a procedure for the modeling strong earthquake ground motion based on autoregressive moving average (ARMA) models. The Generalized autoregressive conditional heteroskedasticity (GARCH) model is used to simulate the time-varying characteristics of earthquakes.

Abstract: Based on Simufact11.0, a 3-D model of T profile extrusion is established and the extrusion process of TC4 is investigated using finite volumemethod(FVM) of Euler mesh description. Effects of different friction coefficients on the effective stress, extrusion pressure, effective strain and effective strain rate have been studied. The study shows that there is a high-stress zone at a certain distance from the entrance of the forming area and a high strain rate zone around that area. With the increase of friction coefficient, the value of the stress increased and the deformation is more uneven. The track of extrusion pressure shows that extrusion increase with the increase of friction coefficient.

Abstract: Under the effect of magnetic field, the removing material will produce by using magnetorheo1ogica1 fluid with contains hard magnetic particles or polishing powder, when the magnetorheo1ogica1 fluid moving relative to the workpiece. Magnetorheological finishing is a promising technology for manufacturing super-smooth components surface. According to Preston equation, mathematics model of magnetorheo1ogica1 fluid is established with the hysteresis shear stress model which composed of viscous and bilinear hysteresis shear stress model. After discussing the relationship between magnetic field and material removal studied, the results show that hysteresis shear stress model can describe the mechanical behavior of magnetorheo1ogica1 fluid perfectly and it is simple in form, explicit and easy to apply. Calculated value is consistent with the experimental values and the mathematical model is thus capable to play a guiding role in processing.

Abstract: Aiming at the strength destruction of high temperature and high pressure valve in the normal condition, an ultra-supercritical steam trap was taken as the research object, the fluid-solid-heat coupling simulation was carried, and the distributions of the fluid pressure and velocity were obtained, the distributions of the whole valve temperature field, the stress and deformation were also obtained. The results show that the valve will not produce cavitation after the depressurizing of multilevel sleeve step by step, and the flow rate is controlled; the maximum stress is found on the connection of the upper sleeve and the gland, the thermal stress values on the import and export of the valve are larger, and according to the stress classification and assessing criterion, they all meet the requirements of strength. It can provide reference for the design and optimization of the high temperature and high pressure valve.

Abstract: Three radiation models are discussed in the present paper. The heat fluxes vary considerably between different methods. In all models, fluxes vary highly on the position of nearing the flame and are almost identical on the far away position. Heat fluxes calculated from point source model is less than other two models, and Shokri-Beyler model is highest. Shokri-Beyler method is most applicable at heat fluxes greater than 5 KW/m² and recommended in engineering design, and Mudan model is not applicable for calculating the heat flux nearing the flame.

Abstract: Reinforced concrete is the main material of the bridge structure, a lot of reinforced concrete bridges in service are needed to be demolished. Firstly, the numerical simulation of blasting demolition of reinforced concrete was introduced; secondly, the separate model of common nodes of the reinforced concrete solid pier was built by using the software ANSYS/LS-DYAN; lastly, the effect of numerical simulation of blasting demolition on the solid pier was analyzed.

Abstract: Mankind is capable of cognizing and handling multiple tasks at the same time. Driving is the task in which the continual combination and alternation of various basic tasks is involved. And, a number of the foresaid basic tasks need to be handled and completed simultaneously; therefore, the research looking into the parallel behavior of drivers is needed. Parallel driving has the attributes, relevance and exclusiveness, that leads to different representations according to various danger classes. In this article, the parallel driving model is put forward, and an experiment is developed to test the performance of the drivers. Through the experiments, validity of the model is verified.

Abstract: Taking a heavy dump truck as the research object, multi-body analysis and movement simulation are carried out on the lifting mechanism to determine the largest lifting time of the hydraulic cylinder. The stress value of key components and corresponding lifting Angle are acquired, and the calculated results and the actually known parameters and data are compared to verify the rationality of the design of lifting mechanism. Using ABAQUS for the strength check of the triangular arm and using OptiStruct for the topology optimization of the part, the mass and the volume of the new part are reduced more than 1 time. The development of part can improve product quality, shorten development cycle and reduce costs. Key words: Lifting Mechanism, Simulation, Strength Check, Topology Optimization

Abstract: Existing active safety technology need the participation of the driver, so individual differences of drivers will affect the work efficiency of the active safety devices. Under the circumstance of the MATLAB/Simulink, reaction time sub-model and vehicle longitudinal collision avoidance system model are established to simulate the movement of the car during its following the target vehicle, monitoring, analysis, judgment and taking measures. The results showed that the system can automatically complete the process of real-time monitoring of vehicle speed and spacing, hazardous situation, taking the deceleration measures, and avoid the collision.