预制裂纹槽加工方法对连杆裂解加工质量的影响规律

通过大量工艺试验研究了预制裂纹槽加工方式对裂解质量的影响规律,结果表明,激光加工裂纹槽生产效率高,裂解加工后大头孔的圆度误差及裂纹线与断裂面的水平误差最小,而拉削加工的裂纹槽上述两项误差值最大,线切割加工方式居中.同时采用有限元数值模拟正交试验,分析了连杆预制裂纹槽几何参数时裂解载荷的影响规律,结果表明,槽深对裂解载荷影响最显著,曲率半径次之,而张角对裂解载荷的影响不显著,并给出了预制裂纹槽合适的工艺参数范围.     

结构不对称对斜切口连杆裂解影响分析

分析了斜切口连杆结构不对称对裂解加工中两侧裂解槽起裂时序及裂解质量的影响.建立了斜切口裂解连杆有限元模型,以试验确定的斜切口连杆材料断裂韧性参数为起裂判据,变化斜切口裂解连杆有限元模型的两侧裂解槽深差,进行了斜切口连杆裂解起裂准静态有限元分析.模拟结果表明,通过优化斜切口连杆两侧裂解槽深度参数可以减小由于结构不对称引起的斜切口连杆裂解加工中两侧裂解槽的起裂时间差.进行了不同槽深情况的斜切口连杆裂解试验研究,通过电测方法测定了试验中斜切口连杆两侧裂解起裂时间差,试验结果与数值模拟结果相比有较好的一致性.     

连杆裂解起裂及三维裂纹扩展分析北大核心CSCD

分析了连杆裂解加工力学原理及切口根部与裂纹尖端应力场,确定了断裂准则并对连杆裂解加工过程进行数值仿真,通过结构中单元失效模拟裂纹的产生与扩展,进而分析裂解槽根部节点应力应变状态、连杆起裂及裂纹扩展情况、连杆大头端和断裂面的塑性变形分布。结果表明:连杆在局部小塑性变形状态下断裂剖分,塑性应变集中分布在裂解槽根部及附近,最大值约为0.035;初始裂纹发生于连杆厚度中面裂解槽根部近表层处,起裂后裂纹平均扩展速度约为19.6m/s,主裂纹扩展遇螺栓孔一分为二,绕过螺栓孔后裂纹扩展速度降低;裂纹在连杆大头端外缘汇合,并易在此处形成挤压,发生爆口及台阶等缺陷,可通过改变连杆大头外缘轮廓形状减少或避免爆口及台阶等缺陷的产生。     

内燃机连杆制造最新技术与发展趋势

连杆裂解工艺是国际上90年代初发展起来的连杆加工最新技术。本文阐述了连杆裂解加工技术的技术原理、经济性、连杆材料特性、初始锻造毛坯、热处理要求、裂解加工工艺与关键核心工序及设备。探讨了在我国研究开发的重要性及应用前景。     

基于裂解设备的连杆裂解加工质量影响分析

连杆裂解方法是近些年发展起来的一种连杆加工新技术,目前正在逐步取代传统加工方法,利用裂解连杆自动化生产线,针对A型连杆完成了激光切割裂解槽工序和定向裂解加工工序,并进行了系统的裂解试验研究。首先讨论了影响激光裂解槽加工质量的因素,其次讨论了裂解槽对于裂解质量的影响,最后讨论了定向裂解工序中,夹具、加载速度及背压力等因素对于裂解质量的影响。系统地介绍了裂解连杆开发过程中出现的各种质量缺陷,并给出了相应缺陷的解决方案,为进一步提高裂解连杆产品的质量提供了可靠的理论与实践基础。     

摩托车发动机连杆的锻造工艺设计

本文通过地摩托车发动机连杆的锻造工艺特点，连杆常用材料及其可锻性的分析，给出了确定全面模同，锻件公差，加工余量，模锻斜度和圆角尺寸的基本原则和方法，介绍了连杆锻造的典型工艺流程及注意事项。     

摩托车发动机连杆的锻造工艺设计

本文通过对摩托车发动机连杆的锻造工艺特点、连杆常用材料及其可锻性的分析,给出了确定分模面、锻件公差、加工余量、模锻钭度和圆角尺寸的基本原则和方法,介绍了连杆锻造的典型工艺流程及注意事项。     

连杆裂解加工数值分析

裂解力的选择是发动机连杆裂解加工成败的关键.为获得合适的裂解力,利用MSC.MARC软件对捷达轿车连杆起裂过程进行了数值分析,得出了裂解力与J积分的关系曲线.根据冲击韧性与断裂韧性的关系,确定了临界J积分值,并采用线性插值的方法获得了裂解力.试验结果表明：此种数值分析方法适合对不同类型和材料的连杆裂解力的确定.     

某型柴油机连杆断裂原因分析

首先从理论上分析了某型柴油机连杆在大端的螺纹孔处断裂的原因,接着从加工工艺上找出了连杆大端螺纹孔的薄弱环节,然后通过连杆疲劳试验,验证了连杆大端螺纹孔的薄弱环节导致连杆断裂,最后提出了加工以及质量管理的改进建议。     

某型柴油机连杆工艺改进研究

针对某型柴油机连杆断裂故障,对连杆小端油孔抗疲劳加工和表面喷丸强化残余应力控制技术进行了研究,并根据研究结果对传统加工工艺进行了改进。工艺改进后的现场试验和小批量试制验证表明:采用新工艺加工的连杆其残余应力控制在合理范围。     

Unerroric of control of mutual compliance of the efficiency of hydrogen engines of unmanned vehicles in the conditions of mass production

The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO₂ and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized.     

小型锅炉烟尘测试时锅炉出力的计算

锅炉烟尘测试时,必须对锅炉出力进行测试。但监测中,许多小型锅炉往往不具备相关的计量装置和仪表,为解决这一问题,文章提出了用烟气量和空气过剩系数来计算锅炉的出力的公式,在实际使用中,该方法简单易行,其结果和实测值具有很好的一致怀。     

中国煤炭地下气化技术的发展

本文综述了煤炭地下汽化技术的国内外发展现状,对我国“长通道、大断面”煤炭地下气化新工艺给予了技术经济评述,并提出了发展煤炭地下汽化技术的政策建议。     

Review of theory of distortion and disintegration of liquid streams

Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined.     

MgO膨胀剂细度对MgO水化和水泥浆体膨胀的影响

基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁（MgO）,研究了该型MgO膨胀剂（MEA）细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析（TG DSC）分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。     

机车车轮多轴疲劳强度安全评定的研究

使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。     

Constructal optimization of the geometry of an array of micro-channels

This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed.     

Heat of vaporization of mixtures

General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996     

固体热辐射Yong性能分析

本文对漫灰均温物体在常物性条件下对外辐射传热的Ｙｏｎｇ值计算建立了数学模型。通过与物体内能Ｙｏｎｇ公式的数值计算比较,得出了辐射能量的Ｙｏｎｇ值不大于内能Ｙｏｎｇ值的结论。从初步的热射Ｙｏｎｇ值计算公式发现。Ｙｏｎｇ与物体表面辐射率有关。     

Measurements of concentration distribution of hydrogen jet using deflection of center of the laser spot

The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%.