新FM法拔长的临界砧宽比、临界料宽比及工艺参数研究

通过有限元模拟新FM法锻造,分析了锻件心部一定区域内的应力场分布规律,得出：对于不同压下率,在不同料宽比条件下,都存在着使轴向应力由拉应力转变为压应力的临界砧宽比l1cr;在不同砧宽比条件下,都存在着使横向应力由拉应力转变为压应力的临界料宽比l1cr。合理的工艺参数应由砧宽比、料宽比及压下率三者匹配确定。数值分析结论,是新FM法工艺参数的精细化。     

平砧连续拔长矩形截面毛坯的数值模拟

对平砧锻造法进行了连续拔长过程的数值模拟.以前的研究仅仅给出了单次压下拔长模拟结果,忽略了上一次压下所产生的变形对后续压下的影响,这里采用ANSYS有限元分析软件对该锻造法实现了拔长一趟过程的数值模拟,并分析了锻件横截面上的中心轴线横向应力分布.分析结果表明:在使用普通平砧拔长时,在砧宽比为1.0和料宽比为0.5的条件下,坯料横截面上的其横向应力都是拉应力状态.并且随着拔长的进行,横向拉应力越来越大.这一点吻合了平砧拔长矩形截面毛坯的新理论,也表明了应用普通平砧锻造法时要注意控制横向拉应力.     

大型锻件锻造的关键技术

大型锻件的常规生产工艺存在萌生裂纹源的变形机制。从宏观力学出发剖析了大型轴类锻件、大型饼类锻件、大型板类锻件的常规生产工艺，指出其容易产生废品的力学机理，提出合理匹配料宽比、砧宽比和压下率来控制毛坯变形区横向和径向拉应力的方法，从而彻底锻合毛坯内部的空洞缺陷，改善毛坯内部金属的组织与性能，防止内部产生裂纹，降低废品率。该方法的可靠性得到生产实践的检验，具有广阔的应用前景。     

无横向拉应力锻造法

无论是平砧拔长还是新FM锻造法,都要对料宽比加以控制,才能实现横向无拉应力锻造。对宽板的最后成形锻造,料宽比是无法控制的。只有改变边界条件,才能实现宽板锻件最后成形锻造（窄边竖直情况）无横向拉应力作用。本文提出了一种新型工具——锥面砧,不需控制料宽比,可达到无横向拉应力锻造。     

不均匀压缩下金属板带面内弯曲成形的试验研究

不均匀压缩下金属板带面内弯曲成形是一种不同于传统塑性弯曲的先进弯曲方法，对由锥辊实现的这一弯曲成形方式的影响因素进行了分析；在此基础上，通过正交试验获得了影响的主次顺序，为建立变形区参数与轧件弯曲半径间的函数关系提供了参考依据：对宽度ｂ０＝３５．３０ｍｍ的ＬＦ２１Ｍ冷轧板带获得了相对弯曲半径Ｒ／ｂ０小至１．２６，对宽度ｂ０＝３１．５８ｍｍ的ＬＦ１２Ｍ冷轧板带，获得的弯曲件最外缘处材料纵向延伸率达７     

CL方程式对Zn－1．8％Al合金超塑性的应用

在Ｔ＝１１０～１９５℃及ε＝０．４×１０（－３）～２．４７×１０（－３）Ｓ（－１）时对Ｚｎ－１．８％Ａｌ合金超塑性ｍ－δ曲线进行了测定，属ｍＬ＝ｍｍｉｎ型。可分为基本形式、上升式及下降式三种形式。应用ＣＬ（刘勤）方程式对Ｃ值进行了计算，获得了全部有关特征参数，包括（δ０＝０），δＬ，δＦ；ｍ０（≠０），ｍＬ，ｍＦ；（Ｃ０＝ｋ０／ｋ０＝１），ＣＬ（＝ｋＬ／ｋ０）及ＣＦ（＝ｋＦ／ｋ０）的全部或一部分，由曲线的形式决定。测到的总延伸率δＦ＝１９０／～４１０％．各自由每根ｍ－δ曲线的其余特征参数的动静态或直间接效应的综合结果所决定。进一步否定了当前超塑性领域内存在的错误观点。并对有关微观变化进行了初步研究。     

往复式压缩机停止供气时的示功图

在压缩机的计算中，容积系数的方程式为λＶ＝１－αＭ（θ×ε１／ｍ－１）（１）式中αＭ—相对余隙容积，αＭ＝ＶＭ／ＶｈＶＭ—余隙容积Ｖｈ—气缸工作容积ε—压出压力与吸入压力之比，ε＝ｐＨ／ｐＢθ—温度系数ｍ—多方指数由吸入终了温度与膨胀终了温度的比值确...     

平砧拔长矩形截面毛坯的新理论

在拔长工艺理论方面,论证了只有砧宽比ω/h一个工艺参数的不足,而应增加一个工艺参数料宽比b/h,才能正确描述拔长毛坯中心区域的应力状态与有效控制锻件质量。该论述已被实验验证。同时用料宽比和砧宽比这二个工艺参数控制锻件内部质量的拔长工艺,简称为LZ工艺。     

圆柱体在普通平板间镦粗时应力场的数值模拟

圆柱体在普通平板间镦粗时应力场的数值模拟。基于平衡方程及塑性条件，应用刚塑性力学模型，以实际试件的外形作为边界条件而解决了问题，求出了原高径比Ｈ。／Ｄ０＝２．３３的圆柱体在压下率为１５％～５０％情况下的内部应力场。这与物理模拟定性试验吻会，且进一步证明与完善了刚塑性力学模型的拉应力理论     

感耦等离子体原子发射光谱法测定高纯铅中杂质元素的干扰研究

文章介绍了用ＩＣＰ－ＡＥＳ法测定高纯铅中杂质元素时，Ｐｂ对分析元素的干扰情况。Ｐｂ对Ｇｅ、Ｍｏ、Ｐ、Ａｓ、Ｆｅ、Ｂｉ、Ｍｎ有背景影响，对Ｓｂ产生谱线干扰。１０ｍｇ／ｍｌ的Ｐｂ分别产生相当于０．２３５μｇ／ｍｌＡｓ、０．７５０μｇ／ｍｌＰ、０．３３５μｇ／ｍｌＭｏ和３．９５０μｇ／ｍｌＳｂ的信号。     

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.