不同衬垫关节轴承摩擦学性能的对比

在摆动频率1.9 Hz,4种载荷(3,6,9和12 kN)条件下,对比研究了1种钢对铜网复合衬垫材料关节轴承Ⅰ和3种钢对PTFE织物衬垫材料关节轴承Ⅱ,Ⅲ和Ⅳ的干滑动摩擦磨损性能,并利用三维形貌轮廓仪观察其磨损表面形貌。试验结果表明:轴承Ⅰ,Ⅱ,Ⅳ的摩擦系数随着载荷的增大而逐渐增大,轴承Ⅲ则随着载荷的增大呈减小趋势;轴承Ⅰ,Ⅱ,Ⅲ,Ⅳ的磨损量和摩擦温度大体上均随载荷的增大不断增大;载荷小于9 kN时,轴承Ⅰ的摩擦学性能表现较好,大于9 kN后轴承Ⅲ则表现最好;整个试验过程中轴承Ⅳ的摩擦磨损性能表现最差。     

磷酸酯偶联剂改性衬垫对自润滑关节轴承性能的影响

利用 Instron5944型电子万能材料试验机和自制的关节轴承摩擦磨损试验机,研究磷酸酯偶联剂接枝改性处理衬垫对自润滑关节轴承黏接性能和摩擦磨损性能的影响。结果表明：磷酸酯偶联剂接枝改性处理衬垫可以有效提高轴承衬垫的黏接性能;自润滑关节轴承的摩擦磨损性能与摆动频率呈现明显的相关性,摩擦因数和磨损量均随摆动频率的增大而减小,而摩擦温度随之升高;衬垫经改性处理的轴承摩擦因数、磨损量以及摩擦温升均明显降低,表明衬垫经改性处理后改善了自润滑关节轴承的摩擦学性能。     

关节轴承衬垫材料摩擦温度研究

在高频压摆摩擦磨损试验机上对自润滑关节轴承衬垫材料进行摩擦学性能研究,探讨不同试验条件下的摩擦温度变化特性。结果表明：载荷一定时,摩擦温度随频率的增加而增加;与其他载荷范围不同,衬垫材料在15~20 MPa载荷范围内的摩擦温度出现降低趋势,表明在该载荷范围内转移膜状态稳定,润滑性能提高。磨屑的显微分析结果表明：摩擦温度对磨屑的大小及组成成分具有决定性影响,摩擦温度越高,产生的磨屑形状越大,增强纤维含量越高,即磨损越严重。通过载荷、频率、摩擦温度的关系图得到摩擦温度等值线图,分析衬垫在不同PV值下的摩擦温度变化趋势,为不同工况下衬垫的选择及其寿命评估提供参考。     

不同黏结方向对织物自润滑衬垫磨损性能的影响

织物自润滑衬垫是飞机关节轴承的关键自润滑材料,其摩擦磨损性能直接影响关节轴承的服役可靠性。对2种型号的关节轴承进行故障分析,结合摆动磨损试验研究衬垫裁剪和黏结方向对衬垫性能的影响。结果表明:45°方向裁剪的衬垫摩擦平稳性和耐磨性均优于0°方向裁剪的衬垫,为提高国产织物自润滑衬垫的服役性能提供了试验依据。     

挤压型不锈钢向心关节轴承的摩擦磨损性能

研究挤压型不锈钢向心关节轴承在不同的试验参数下的摩擦磨损性能,分析其摩擦磨损形式。结果表明:不锈钢向心关节轴承的磨损形式以黏着磨损和磨粒磨损为主,磨损量随载荷的增大而增大,随摆动频率先减小而后增大;摩擦因数随载荷和摆动频率的增大而减小。     

编织衬垫关节轴承热力耦合分析

根据关节轴承相关的热传导理论,建立了基于ABAQUS仿真软件的动态热力耦合模型,分析了编织衬垫关节轴承温度、应力、变形的分布规律及摩擦热对轴承力学性能和结构尺寸的影响。运用自制的关节轴承试验机对轴承温度进行实时测量,得到热平衡状态时关节轴承内圈温度场的分布,并与ABAQUS热力耦合模型中关节轴承试验测点所对应的温度场分布进行对比。结果表明:相较于无摩擦热时,有摩擦热时内圈和衬垫的变形量变小;在接触区域衬垫变形呈现波动分布,与内圈的接触面积变大。适当的摩擦温度可以缓解编织衬垫关节轴承的应力变化,改善关节轴承的力学性能,延长使用寿命。试验与仿真结果的一致性验证了仿真模型的准确性。     

纤维织物型自润滑材料摩擦学性能试验

采用标准球盘往复式摩擦磨损试验机对纤维织物型自润滑关节轴承材料的摩擦特性及磨损机理进行试验,测定恒定载荷和往复运动条件下衬垫的摩擦因数和磨损量,给出了衬垫与试球间接触应力分布计算式。通过方差分析及检验样本P值验证了不同条件下测试均值差异的显著性及数据的有效性;应用扫描透射电子显微镜观测衬垫磨后的表面形貌,分析磨损机理;采用3种对磨试球,对比不同材料对衬垫摩擦学特性的影响。     

基于有限元法的自润滑关节轴承静力学分析

根据GE30C自润滑关节轴承的实际结构、边界条件和工作载荷,建立了自润滑关节轴承的有限元模型,利用ANSYS workbench 13.0分析额定静载荷作用下自润滑关节轴承的应力和变形情况,得出衬垫的接触应力分布。通过改变衬垫的弹性模量,得出相应的接触应力和衬垫变形量,讨论衬垫材料的弹性模量对关节轴承性能的影响,为选择合适的自润滑衬垫材料提供参考。     

铜基粉末冶金和青铜衬垫杆端关节轴承摩擦学性能对比

采用自制的高频重载杆端关节轴承摩擦磨损试验机,在摆动频率3 Hz,接触应力8 MPa条件下试验分析了铜基粉末冶金和青铜衬垫杆端关节轴承的摩擦因数、温升和磨损情况,借助扫描电子显微镜(SEM)检查分析了2种衬垫的表面磨损差异。结果表明:铜基粉末冶金衬垫轴承的摩擦学性能优于青铜衬垫,且前者为轻微磨粒磨损,后者为严重磨粒磨损。     

E06—12型自润滑杆端关节轴承试验机

E06－12型自润滑杆端关节轴承试验机是利用曲轴-摆杆机构，杠杆加载原理实现试验轴承每分钟摆动20～40次，摆角幅度20°～40°，最大径向载荷9．8kN。介绍了该试验机的主要技术指标和设计特点，并提出了进一步的改进措施。     

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.