Advanced Materials Research Vols. 189-193

Abstract: The stand is the largest and most important part in rolling-mill components.It bears tremendous rolling force, instant impact and part of the rolling torque during the rolling process .In addition ,roller system ,pressure and balance system also installed in it. Therefore, rolling mill must be equipped with sufficient strength and stiffness to ensure the safety of mill equipment and accuracy of the size of products. In this paper, It uses the finite element simulation software MSC.Marc to simulate and analyze the 3-D finite 5-m heavy plate mill housing of Baosteel . which can provides effective theoretical basis to the optimization of technology establish and the safety of equipment. The simulation results can be used to verify the accuracy of stress and strain field measured data for the mill frame, It also can infer parts of rolling mill which is not detected and unpredictable of the stress and strain states, and further to learn about weak parts of frame in stiffness and strength facets.

Abstract: Grinding is one of the most important operations in material processing. The study on grinding mechanism is difficult to carry out because of the difficulty in measuring the actual grinding temperature, stress and strain by experiments. Finite element analysis software Deform-3D is employed to create the Johnson-Cook material constitutive model for high-speed grinding simulation. Grinding model was constructed to reflect the temperature, strain and strain rate in the process of grinding 40Cr steel. The temperature of grinding area in simulation is analyzed to verify whether the finite element model is reasonable.

Abstract: On the basis of numerous experimental results the effect of heat treatment on mechanical properties of TC4 alloy is studied. A computer model expressing the relationships between heat treatment and mechanical properties has been established with supported vector machine method. The input parameters were determined by the heating temperature and heating time which are important factors of the mechanical performance, and the output parameters are tensile and yield strength and elongation. The model is established by libsvm with RBF kernel function, e-SVR and proper parameters. Experimental results show that prediction accuracy made by using support vector machine reached over 95%, and the model has good learning precision and generalization and it can be used for predicting the mechanical properties of TC4 alloy.

Abstract: The paper’s main content is that simulating the process—drawing the high-strength steel-DP500 which is used on automobile to the cylindrical cup through the commercial finite element simulation software—Dynaform. Through the simulation, the author analyzes the effect that friction impacts on drawing high-strength steel. The result is that: if the friction coefficient between the blank and the die declines, it can significantly improve the uniform of the blank’s thickness distribution; it can enlarge the processing range of DP500 steel through decreasing the friction coefficient; the springback is sensitive to the change of the friction condition. Generally speaking, in drawing process, improving the friction coefficient is very important to increase the drawing performance of the cylindrical parts.

Abstract: This paper presents the effects imposed on the reliability of advanced-process CMOS devices, specifically the NBTI degradation, subsequent to the integration of laser annealing (LA) in the process flow of a 45nm HfO₂/TiN gate stack PMOS device. The laser annealing temperatures were varied from 900°C to 1350°C. The effects imposed on the NBTI degradation of the device were comprehensively analyzed in which the shifts of the threshold voltage and drain current degradation were observed. The analysis was extended to the effects of the conventional RTA as opposed to the advanced laser annealing process. It was observed that the incorporation of laser annealing in the process flow of the device enhances the NBTI degradation rate of the device, in contrast to the integration of the conventional RTA. Laser annealing subsequent to spike-anneal is observed to improve the reliability performance of the transistor at high negative biases.

Abstract: The novel Fomichev plug described in this paper is of characteristic producing equal unit-reduction of wall thickness along its perforation section during seamless tube piercing, which designed on the base of the roll opening of Julong piercer, taking into account for both feed angle and toe angle of a cone type piercer. Then a 3-D thermal-mechanical coupled numerical simulation on performance characteristic of novel Fomichev plug is presented with the aid of commercial FE code MSC.SuperForm, according to practical process parameters of piercing and rolling for steel grade P91 on Julong piercer in Yangzhou Chengde Steel Pipe Co., Ltd. By comparison with conventional plugs, as FE simulation result shows that the new plug reduces the damage value of the workpiece, thus decreases the tendency of lamination defects. What’s more, the axial resistance of novel Fomichev plug is smaller than the conventional, which is in favor of biting condition and increases piercing efficiency. Furthermore, the newly-designed plug’s temperature field is more uniform, which can alleviate failure of piercing plug caused by overtop local temperature, prolong its working life, and improve the quality of hollow shells.

Abstract: With the good characteristics of high efficiency, energy saving and environmental protection, supercritical W-flame boiler can effectively solve the problems of clean and high efficiency combustion of poor-quality anthracite using for supercritical pressure boilers. In light of a 600MW supercritical W-shaped flame boiler, combustion models in fluent 6.3 were used to study the combustion law of poor-quality anthracite in the furnace, the effect of air distribution on the combustion process was analyzed. The results indicate that symmetrical air distribution can not form symmetrical flow field because of the structure effect of the nose of the furnace. The effect of the nose of the furnace can be effectively balanced by increasing the velocity on the front wall and there exists an optimal ratio of air distribution. In the central zone of the lower furnace, the temperature is high and the O2 concentration is low, which is beneficial to the ignition and combustion of pulverized coal. Because the pressure in the center of the furnace is higher than that near the side walls, the pulverized coal are forced to move towards the side walls, which can cause the sidewalls to be eroded by the flame and slagging. The study results have great significance for the optimization design and improving the efficiency of pulverized coal combustion of supercritical W-shaped flame boiler.

Abstract: The neural network (NN) is extensively used for error predication and compensation in CNC machining. However, the training samples are finite and have some noises which limit the training accuracy of the neural network. Furthermore, the weight matrixes and the valve values of the NN are fixed which limit the generalization performance of the trained NN. To solve the problems, some optimization techniques are proposed in this paper. A standardized formula is proposed to standardize the training samples. The data filter is designed to eliminate the noise. A correction strategy is proposed to realize the generalization performance of the trained NN.

Abstract: The paper sets up a virtual prototye modeling for a high-dump truck and has dynamic simulation for this modeling.At the same time,it analyses the related results.The high-dump truck adopts the scissor lifting mechanism to upgrade the compartment smoothly. The lifting mechanism and the median installation of fuel tank in the flip institutions are novel. The simulation analysis results of ADAMS confirm the feasibility of this design and make some proposal for the rationality of the median installation of fuel tank.

Abstract: A multi-factor diffusion model of chloride in concrete was formulated, in which the hypothesis of Fick’s Law were corrected through parameter definition. The values of the parameters in the model were given for practical applications according to pilot calculation and analysis of mass data. By using this diffusion model, three calculation methods of concrete structure service life were further deduced, it includes definite value method, probability performance based method and time-dependent reliability based method. The service life prediction for the approach bridge of Huang-pu Bridge was carried on by using various prediction approaches mentioned above. The results showed that: time-dependent reliability based method can consider randomness of chloride diffusion coefficient and the depth of concrete covering layer, and the stochastic characteristic of environment variable can be easily taken into account too. By adjusting the target reliability, the prediction results are consistent with those of the other two methods.