有利于提高硬态切削滚动轴承疲劳寿命的残余应力临界条件

超精硬态切削在滚动轴承表面形成的残余压应力 ,经工作应力衰减后才成为影响滚动接触疲劳寿命的应力状态。基于此 ,本文在考虑特定滚动轴承使用条件的基础上 ,推导出滚动轴承采用超精硬态切削加工工艺时 ,已加工表面的残余应力需要满足的两个临界条件 ,即在接触区的每一离散点的残余应力必须与工作应力符号相同 ,且随时间变化残余应力的幅值应小于或等于工作应力幅值的两倍时 ,才有利于提高滚动轴承的使用寿命。该结论澄清了长久以来文献中所提出的残余压应力总是有利于提高工件疲劳寿命的这个似是而非的概念。     

M50NiL材料复合化学热处理后残余应力的预测

为了预测渗层中残余应力的分布状态,选用不同工艺参数对M50Ni L材料进行复合化学热处理,分析不同工艺参数下渗层的硬度梯度及残余应力,研究硬度梯度与残余应力的关系,建立残余应力的预测模型。经过残余应力的测定,验证了该模型的准确性。     

钢瓶热处理对其残余应力影响的试验研究

对经过不同热处理工艺处理的YSP－15型钢瓶的残余应力进行测定，得出钢瓶残余应力的分布规律，并分析热处理对残余应力的消除效果。     

冲压套圈热处理工艺试验

对JHOR/40 70冲压套圈热处理试验所用设备、工艺和工艺参数作了介绍 ,并对热处理后的尺寸、变形、组织结构、渗层深度、残余应力及残余奥氏体进行了测定与分析。分析结果表明 ,尺寸及组织等均达到有关技术要求。附图1幅 ,表 1个。     

低碳马氏体在气门弹簧上座上的应用

气门弹簧上座是我厂成批生产的495A型柴油机上的一个零件,详见图1。此零件原用φ38毫米的45钢车削、调质处理而成,既浪费工时又浪费材料。为此我厂工艺试验组对气门弹簧上座旧工艺进行革新,用低碳钢冷挤和低碳马氏体的热处理工艺相结合来取而代之。我们采用φ28毫米的20钢冷挤压成型,成型后的零件几何尺寸精度完全达到设计图纸要求。但是,由于20钢含碳量较低,调质热处理硬度达不到图纸设计要求的HRC 25～31。为了解决这一矛盾,我厂热处理部门大胆提出对20钢冷挤成型的气门弹簧上座采用强烈淬火方法,使     

盲孔法测定Ti700SR钛合金焊接件残余应力实验研究

本文采用盲孔法对Ti700SR材质测试件进行铸态、焊接态、退火态残余应力进行测定，分析在特定焊接工艺下进行3种温度热处理后残余应力消除情况，为制定合理的热处理方案提供了可靠数据。研究表明，焊接态试验件中残余应力相较铸态升高了300%左右，经高于700℃热处理后应力得到释放，且低于铸态下的残余应力。结果显示，采用700℃、1h退火工艺就可以有效地消除焊接残余应力。     

轴承钢顺次磨削表面残余应力离散度试验研究

以轴承钢顺次磨削表面的残余应力离散度为研究对象,基于X射线衍射法顺次测试了轴承套圈淬硬热处理、粗磨、精磨和超精磨削后,轴承滚道表面环向和轴向残余应力.测试结果表明,淬硬热处理工件的残余应力标准差约为超精工序的3倍;淬硬热处理轴承套圈经超精磨削工序,其表面的环向和轴向残余应力离散度降至20 MPa.研究表明淬硬轴承钢热处理及同一道磨削工序工件表面残余应力存在较大离散性,"粗磨-精磨-超精"顺次磨削工艺叠加后,工件表面残余应力离散度呈现收敛性;淬硬热处理轴承套圈经过顺次磨削工序叠加加工后,表面残余压应力平均值获得大幅提高.这为进一步系统揭示磨削工艺对淬硬轴承钢套圈表面残余应力及其离散度影响规律提供了科学数据.     

气门弹簧动力计算的有限元方法

在发动机配气机构中，气门弹簧的刚度较低，容易在外部激励下发生共振，其应力幅度可增加５０％或更大。因而在气门弹簧的设计试制阶段，需要一种有效的对其进行运动与应力分析的手段。本文采用有限单元法，推导出气门弹簧的动力计算模型，并用此模型对某些发动机气门弹簧进行了动力分析，求出了该气门弹簧固有振型、自振频率及各簧圈的运动和振动。计算结果表明，该模型具有较高的精度并得出了一些有益的结论。     

磨齿表面残余应力研究进展

综述了国内外有关磨齿表面残余应力的研究进展,分析了磨削变质层残余应力的产生机理;可通过控制热处理工艺与磨削工艺,且后续可选择表面恢复与强化技术,使磨齿表面残余应力合理分布。     

65Mn弹簧垫圈热处理工艺

对65Mn波浪形弹簧垫圈原有的回火工艺加以改进,采用不同的工艺对其进行热处理,并作压缩试验检测弹性性能,比较、分析各种工艺热处理后弹簧垫圈压缩试验的结果,结果表明弹簧垫圈最佳热处理工艺为260℃低温回火。     

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.