机载计算机锁钩断裂失效机理分析及工艺改进

锁钩是航空机载设备上的主要受力件之一,在进行耐久试验过程中,发生了断裂失效现象。通过强度分析、断口分析和金相分析得出材料强度满足试验要求,锁钩圆角处基材表层存在的裂纹在随机振动过程扩展及增长导致了此次锁钩断裂失效。从工艺过程对锁钩的加工提出了改进措施和要求,可以解决锁钩零件因裂纹导致断裂失效的问题。     

重型车辆变速器齿轮轮毂断裂失效分析及改进措施

针对变速器一挡主动齿轮在试验过程中发生断齿这一早期失效问题,进行了失效齿轮轮毂的化学成分检验、断口分析和金相组织形貌检测分析等失效机理研究.分析结果表明,花键槽圆角过小、轮缘厚度不足及齿根喷丸强化不足是造成失效齿轮轮毂异常断裂的主要原因.采用有限元建模进行失效齿轮的接触应力分析,并提出了改进措施.     

农用车发动机球墨铸铁曲轴断裂失效分析

采用断口分析、硬度检测、化学分析、金相组织检测等方法对球墨铸铁曲轴断裂的原因进行了综合分析.结果表明曲轴颈与曲臂圆角处光洁度差,原加工痕未磨削消失是疲劳断裂的主要原因.     

汽车半轴断裂失效分析

通过宏观分析、显微组织和断口形貌观察以及硬度测试等方法对汽车半轴的断裂原因进行了分析.结果表明,汽车半轴的断裂是由于拆换轴承不当导致半轴表面损伤产生裂纹源,后经反复的磨损及受力,其裂纹不断扩展,并最终断裂.     

石油钻铤开裂失效分析

一根直径为Φ159 mm的油田钻铤在使用时发生开裂,通过对失效钻铤进行化学成分分析、金相组织分析、SEM分析及力学性能测试等,研究了该钻铤的失效机制.结果表明:该钻铤失效属于疲劳断裂破坏,疲劳裂纹形成于钻铤内螺纹消失处最后1个～2个螺扣部位,该处存在较大应力集中,同时单位面积受力较大,应力状态复杂,使用过程中容易萌生疲劳裂纹,最终导致裂纹的贯穿.     

QJ150FMH摩托车曲轴失效断裂分析及措施

发动机是摩托车的核心部件,曲轴则是发动机的关键支撑部件。曲轴可将活塞往复运动传来的推力转换为旋转运动的扭力,在应力或应变的连续重复变化中,曲轴材料会因性能性质的变化导致失效乃至断裂、开裂。对QJ150FMH摩托车曲轴出现的几种失效情况进行系统分析。借助直读光谱仪、金相显微镜、硬度计等仪器设备,测量断裂曲轴的断口,通过这些方法,推断出QJ150FMH摩托车曲轴早期断裂失效的问题所在,并提出改进断裂失效的解决方法,可以有效地把握曲轴内部组织品级和外在无损要求,预防曲轴发生早期断裂失效。     

高压高速下摆线马达输出轴的疲劳寿命研究

BM系列摆线马达在各个行业运用潜力越来越显著,特别是高压化、小型化改进后的产品更受欢迎,但高压化技术推广过程中输出轴疲劳断裂的问题也相应增多。根据用户反应的情况,马达大致的失效情况为:键齿破坏、轴头断裂。为提高疲劳分析的效率与准确性,根据失效形式,结合国外先进的疲劳分析技术,以传统理论为基础,建立新的疲劳分析方法,对输出轴的失效进行分析。通过对比真实失效情况,验证新的疲劳分析方法的可行性,并且具有实际意义,可以为今后机械零件的可靠性研究提供参考。     

复合板封头开裂失效原因分析

通过宏观分析、微观组织分析和扫描电镜分析等方法分析了DN6200复合板封头开裂的原因.结果表明,不锈钢板双面焊中心连续分布的线型缺陷是DN6200复合板封头加工时开裂的一个重要源头;碳钢基材内部大量的空洞是过载断裂时大韧窝的来源,是造成材料组织不均匀的重要原因之一.     

副励磁机轴断裂失效分析

通过分析副励磁机轴断裂的宏观、微观组织形貌 ,得出该轴断裂的主要原因是夹杂物和其所受的附加弯曲应力 ,最好的改进办法是通过热处理或更换材质。     

泵轴失效的分析

本文通过电镜、金相显微镜、硬度仪、光谱仪等检测手段,对扬子石化炼油厂输送蜡油泵的断裂轴进行了检测,并对检测结果进行分析,结果表明泵轴断裂属疲劳失效.造成疲劳的主要原因是泵轴的倒角半径R值过小.为此,提出相应的改进措施,效果良好.     

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.     

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....     

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。     

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.