铝合金零件半固态压铸技术应用研究

以水泵盖为目标零件,使用A357合金和新型铝合金Al-6Si-2Mg研究了半固态触变压铸过程中的工艺参数对零件最终性能的影响.通过对普通液态压铸机的改进和相关工艺参数的调整,进行了半固态触变压铸试验研究,得到了充型完好、组织均匀的水泵盖零件.     

塑料模具超塑性材料及成形研究

本文研究、制造了四种铝基耐磨、耐蚀塑料模具超塑性合金-Al-13Si、Al-10Si-1Mg、Al-7 Si-1.5 Cu-0.7 Mg 和Al-8.2 Mg-4.7 Si。通过超塑性拉伸试验证明,四种合金均显示出超塑性能。研究了四种合金的超塑化工艺并给出了合金的最佳超塑工艺参数。模具超塑成形试验解决了铝基超塑合金高温成形时的脱模、润滑及成形后的清洗问题。试验结果表明,四种合金都具有良好的超塑成形性能、光洁度高、复制性能好,是较为理想的塑料模具超塑性成形材料。     

过共晶Al-Si合金半固态触变成形本构方程

通过对过共晶Al-20Si-3Fe-1Mn-4Cu-1Mg合金进行半固态单向压缩热模拟试验,研究变形温度为833 K、853 K 、873 K,应变速率为0.1 s–1、0.01 s–1、0.001 s–1的半固态触变成形行为。试验结果表明,变形抗力随变形温度的升高而降低,随应变速率的增加而增大。对试验得到的真实应力应变曲线进行分析,提出将不同真应变范围的半固态触变成形过程划分为类弹性变形、应变硬化和流变-黏塑性变形阶段的新方法,并分阶段建立半固态触变本构方程,采用多元回归得到各阶段的本构方程表达式。所建半固态触变本构方程与试验曲线的比较结果表明,大多数相关系数均在0.95以上,相伴概率均小于0.001,说明根据所建本构方程计算得到的真应力-真应变曲线与试验曲线吻合良好,所建本构方程有意义且具有较高的精度,能够体现出该合金半固态触变过程变形行为,可以将其应用于过共晶Al-20Si-3Fe-1Mn-4Cu-1Mg合金半固态触变成形过程的数值模拟。     

半固态材料触变成形通用本构方程及其优化

采用半固态成形机理分析和试验研究相结合的方法,建立半固态触变成形的粘塑性本构方程,并提出本构方程的优化新方法。通过半固态Al-4Cu-Mg合金的等温压缩试验研究,分析试验数据,得到本构方程中的4个待定系数,并以此作为优化设计的初试值。结合本构方程的形式,对其进行特性分析和优化。将含优化变量的本构方程作为子程序引入到有限元数值模拟中,可以得到对照热模拟试验结果的若干工艺条件下半固态Al-4Cu-Mg合金的应力应变曲线。通过比较有限元数值模拟结果和热模拟试验结果可知,利用提出的本构方程优化新方法,不仅可以剔除热模拟试验数据中几何效应的影响,而且还能准确地描述半固态材料的触变成形规律,从而可以提高数值模拟的精度与可靠性。     

半固态成形技术讲座 第一讲 半固态成形、特点及应用范围（下）

非枝晶材料半固态加工：非枝晶材料半固态加工(即半固态加工)的工艺实质是将凝固过程中的合金进行强力搅拌，使其先凝固的树枝状初生固相破碎而获得一种由细小、球形、非枝晶初生相与液态金属共同组成的液固混合浆料，即流变浆料。将这种流变浆料直接进行成形加工，称为半固态金属流变成形；而将这种浆料先凝固成铸锭，再根据需要将金属铸锭分切成一定大小，使其重新加热至固液相温度区间再进行加工称为触变成形。     

半固态成形技术及其应用

介绍了半固态成形技术的工艺原理,分析了机械搅拌、电磁搅拌、应变诱导、冷却斜坡等浆料制备方法和流变加工、触变加工、注射加工等成形方法。分析了各种计算机模拟技术和模拟方法在半固态成形方面的应用,论述了目前国内外半固态成形技术的应用状况和发展趋势。随着半固态成形技术研究水平的不断提高,成形产品及应用不断增多,发展前景广阔。     

喷射成形制备钢/Al-Pb合金轴瓦材料的研究

利用自行研制的大型喷射成形装置,对成分为Al-6.5Pb-4Si-1Cu-0.5Sn的合金轴瓦材料进行了喷射成形工艺研究。并制备了晶粒均匀密度良好的板坯。研究了合金的显微组织与性能。研究表明：喷射成形Al-Pb合金的显微组织为均匀细小的Pb相粒子弥散分布在Al基体中。这些细小的Pb相粒子对提高合金耐磨性具有很大帮助。喷射沉积成形钢/铝复合板经50％轧制变形后可获得良好的结合强度及组织性能,可做汽车的轴瓦材料。     

Al-Mg-Si系铝合金的成分设计

采用Thermo-Calc软件计算了Al-Mg-Si系相图,得到了固溶温度与Mg2Si含量的关系曲线.以优化Al-Mg-Si系铝合金成分为目的,选取不同镁、硅含量的合金进行拉伸试验,得到了Mg2Si含量与抗拉强度的关系曲线.根据固溶温度、Mg2Si含量及抗拉强度三者之间的关系以及铝合金对强度性能的要求,可以计算镁、硅含量,并可参照固溶温度、Mg2Si含量及伸长率的关系设计出满足一定要求的Al-Mg-Si系铝合金的成分.     

举固态成形技术讲座 ——第二讲 半固态成形工艺过程分析（下）

在半固态棒坯触变成形之前，先要根据零件重量，精确分割经流变铸造获得的半固态棒坯，即所谓下料。然后在感应炉中加热至半固态以供后续成形，这便是二次加热。经二次加热，可获得不同体积分数的半固态浆料，同时也可使在制坯工序所获得破碎枝晶组织球化、均匀化，有利于触变成形。     

半固态铸造技术的研究状况及应用

半固态铸造技术以其高效、节能、近终化成形以及成形件性能优异等诸多特点,在汽车、计算机、通讯电子、航空航天等尖端领域具有广阔的应用前景,逐渐获得广泛关注。介绍了半固态铸造技术的工艺原理、工艺特点、半固态合金的制备、半固态合金的成形方法以及半固态铸造技术的工业化应用,最后对半固态铸造技术的长远发展作了展望。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.