汽车前翼子板拉深成形模拟中两种工艺方案比较

为了给汽车前翼子板拉深成形工艺和模具设计提供依据,对两种典型的拉深成形工艺方案作了对比和分析。首先分析了前翼子板的特点并建立了其拉深模具的工作部分零件模型;然后在Dynaform软件中,利用有限元模拟方法,分别对设置和未设置拉延筋时的可能存在的材料流动和拉深缺陷进行模拟。对成形件的危险区域进行预测,并通过调整拉深筋的布置,压边力以及坯料的形状等,预估了主要的拉深工艺参数。该模拟结果可以用于指导前翼子板拉深生产。     

An artificial immune network for multiobjective optimization problems

Multiobjective optimization is an important problem of great complexity and evolutionary algorithms have been established as a dominant approach in the field. This article suggests a method for approximating the Pareto front of a given function based on artificial immune networks. The proposed method uses cloning and mutation on a population of antibodies to create local subsets of the Pareto front. Elements of these local fronts are combined, in a way that maximizes diversity, to form the complete Pareto front of the function. The method is tested on a number of well-known benchmark problems, as well as an engineering problem. Its performance is compared against state-of-the-art algorithms, yielding promising results.     

Sensitivity aware NSGA-II based Pareto front generation for the optimal sizing of analog circuits

This paper deals with multiobjective analog circuit optimization taking into consideration performance sensitivity vis-a-vis parameters' variations. It mainly considers improving computation time of the inloop optimization approaches by including sensitivity considerations in the Pareto front generation process, not as a constraint, but by involving it within the used metaheuristic evolution process. Different approaches are proposed and compared. NSGA-II metaheuristic is considered. The proposed sensitivity aware approaches are showcased via two analog circuits, namely, a second generation CMOS current conveyor and a CMOS voltage follower. We show that the proposed ideas considerably alleviate the long computation time of the process and improve the quality of the generated front, as well.     

摆动皮带机的结构优化设计

对摆动皮带机的主体部分和前支架部分进行结构优化改造,摒弃了传统皮带输送机大、笨、重的结构,更加适合纤维轻盈和对环境要求洁净的特点。使用钢板折弯机架代替了原来的槽钢焊接支架,镀锌钢管代替了传统的皮带托辊,滑动导轨创新地采用了H型钢,减轻了自重,降低了制造工艺和装配难度,节约了制造成本;降低了更换皮带的难度,使得摆动皮带机能够更好地为生产服务。     

前驱柴油机匹配五菱宏光的动力总成改进设计

分析了前驱柴油机匹配前置后驱车型五菱宏光对动力总成零件周边的静态设计间隙要求.介绍了对应于柴油机由前驱更改为前置后驱发动机的动力总成零部件设计更改情况,以及相应的实车间隙测量和可靠性路试验证结果,对紧凑型商务车由前驱柴油机改为前置后驱的动力总成改进设计具有一定的参考价值.     

Analysis of the scale up of a transpiring wall reactor with a hydrothermal flame as a heat source for the supercritical water oxidation

Experimental data from a tubular reactor and from a transpiring wall reactor (TWR) are used to analyze the scaling up of SCWO reactors operating with a hydrothermal flame as a heat source. Results obtained with the tubular reactor show that fluid velocity inside the reactor determines the minimum injection temperature at which a stable hydrothermal flame is formed. When the fluid velocity inside of the reactor is lower, the extinction temperature of the hydrothermal flame in that reactor is also lower. Using this reactor, extinction temperatures are always near or above the critical temperature of water. Total TOC removals are possible working with isopropyl-alcohol at temperatures between 650 and 700 °C and residence times of 0.5 s. Results of the TWR show that steady operation with a hydrothermal flame inside is possible even when reagents are injected at subcritical conditions as low as 170 °C. Temperature measurements show that reaction is not initiated in the injector but in the reaction chamber, where fluid velocity is lower than 0.1 s. This was explained by estimating that the flame front velocity of a hydrothermal flame is of the order of 0.1 m/s. Thus, it is expected that the flame is stabilized in the reaction chamber and not in the injector, where fluid velocities are higher than 2 m/s. A previously developed model of the TWR was modified in order to describe the ignition in the reaction chamber and not in the injector. The model reproduces satisfactorily experimental data and it was used to propose the design of scaled up reactors for SCWO with a hydrothermal flame inside.     

Local flexibility of an elliptical cracked shaft under bending and tension

Compared with the widely used straight front crack model, an elliptical front crack has been found to be more accurate and realistic for modeling the transverse surface crack in rotating machinery. Therefore, based on the strain energy release rate (SERR) approach and the closed-form results of SIFs, the local flexibilities of an elliptical cracked shaft submitted to bending, axial tension and combination of both are derived and solved by means of numerical integration technique. Once the elliptical front and shape variation are considered, the obtained flexibility values are reduced obviously in contrast with the current results, especially for the deeper surface cracks.     

抗滑桩桩前滑体抗力分布规律及工程应用研究

抗滑桩设计荷载包括滑坡推力和抗滑桩桩前抗力,桩前抗力在水平方向上被认为是均匀分布的，为研究桩前滑体抗力的分布规律，在分析抗滑桩与桩间土体相互作用的基础上，利用FLAC-3D有限差分软件，进行计算。计算结果表明，桩前抗力在水平方向上呈现中间大两边小的趋势，分布规律与桩间距、滑坡推力、桩截面尺寸、土体参数等因素有关。按目前规范推荐的方法，抗滑桩的结构设计是偏不安全的。     

40t煤矿用支架搬运车前机架的有限元分析

主要针对进口40 t支架搬运车运行时出现的问题,用有限元软件进行了受力分析,并对易断裂部位提出3种解决方案加以改进。通过改进该搬运车易断裂部位的结构,延长了该设备的使用寿命,也提高了经济效益。     

变导程锥状正螺旋面的研究及其投影图与展开图画法

本文分析了变导程螺旋运动的一般规律及方程,对由此形成的变导程锥状正螺旋面以及决定该曲面投影图与展开图画法的变导程圆柱螺旋线和变导程圆锥螺旋线进行了研究,建立了它们的参数方程.从而为变导程锥状正螺旋面的画法找到了依据,也为计算机绘制其投影图与展开图提供了数学模型.