PW200转向架的概率疲劳强度

以包含长寿命范围在内的16MnR钢焊接接头和ZG25钢概率延拓S-N关系为基础，得到材料疲劳强度分布。针对考察的PW200转向架不同关键部位，分别选取适当的表面加工系数、尺寸系数，获得转向架结构细节综合影响系数。在此基础上，通过对材料疲劳强度进行修正，获得转向架各部位的概率疲劳强度，为转向架的疲劳可靠性分析提供参考。     

高速客车转向架构架焊接接头疲劳可靠性分析

为研究构架焊接部位的疲劳可靠度,根据国内Q345焊接头的疲劳数据,结合包含超长寿命概率S-N曲线,建立了动车组转向架焊接构架横向对接、横向T形和纵向T形焊接头的概率疲劳S-N曲线。以我国高速动车组典型的CRH2动车组转向架构架为研究对象,确定了其焊接构架吊挂点附近31个焊接头局部的疲劳应力。结合概率疲劳S-N曲线进行了较大应力部位的疲劳寿命预测和可靠度评估。结果说明:齿轮箱吊座与横梁附近的焊接部位是较危险的部位;在置信度97.5%、可靠度0.975下的寿命为3.88×108循环;在置信度97.5%、寿命为109循环的可靠度为0.948 2。     

基于Bayes方法的挖掘机动臂疲劳寿命可靠性评估

针对某型号中型挖掘机动臂在极小样本下的可靠性试验评估问题,基于挖掘机工作装置的疲劳寿命服从对数正态分布,结合单子样挖掘机动臂的疲劳试验数据,利用贝叶斯(Bayes)方法对其寿命可靠性进行了评估,给出了可靠度函数、失效分布函数、失效率函数等可靠性指标,获得了动臂结构在75%置信度、95%可靠度下的疲劳寿命为4071.6小时。为验证评估方法的准确性和有效性,采用了国际焊接协会(IIw)标准对动臂疲劳试验发生裂纹的结构细节进行了疲劳寿命评估,得到相同条件下动臂疲劳寿命为4378.1h。对比结果表明,两种评估结果相对误差仅为7.5%。该挖掘机在90%置信度下平均寿命为7673.2h,与验前信息8000h也比较吻合。     

置信度条件下轴承寿命的可靠度分析

汽车轴承的寿命一般有置信度下可靠度的要求。基于Bayes方法分析确定了可靠度和置信度的关系,进一步采用中间秩确定了轴承给定置信度和可靠度的额定寿命修正系数,最后给出了验证置信度和可靠度的寿命试验方案的制定方法。     

HXD1C型大功率机车传动系统齿轮的疲劳可靠性分析

基于标准和可靠性曲线,分析了HXD1C大功率机车传动系统齿轮的接触和齿根弯曲疲劳可靠性。结果表明,按照齿轮标准计算方法,齿轮的啮合接触疲劳强度和齿根抗弯强度合格。基于接触和齿根弯曲疲劳可靠性曲线的分析结果表明,在置信度95％及可靠度0．99下,齿轮的抗弯疲劳强度较弱,寿命321．32万公里;在置信度95％及期望寿命80万公里下,传动齿轮的抗弯疲劳强度仍然较弱,可靠度水平为0．9971。     

25Cr2MoV 气体渗氮齿轮弯曲疲劳强度的试验研究

论述25Cr2MoV深层渗氮齿轮弯曲疲劳强度的试验研究。试验在英国产STRON1603型电磁谐振疲劳试验机上进行。短寿命区采用四级恒定应力水平的成组试验法,长寿命区采用应力升降试验法。在试验数据基础上,根据统计学原理,拟合出完整的C-R-S-N曲线,并获得各种置信度和可靠度下的弯曲疲劳极限值。     

基于道路载荷的汽车结构件可靠性试验方法研究

基于疲劳伪损伤相关性分析,建立了与道路载荷等效的程序载荷谱;对构件疲劳寿命进行了威布尔分析,建立了在一定置信度、可靠度条件下最少样件的可靠性试验方案。通过变速箱支架台架可靠性试验,复现了与道路试验相同的失效模式、疲劳失效寿命,分析了影响变速箱支架疲劳寿命的因素,并验证了试验方法的有效性。     

基于动应力的地铁构架疲劳损伤与疲劳寿命计算

作为轨道车辆走行部的极关键结构,转向架构架的服役安全性受到极大重视与关注。以新设计的地铁车辆动车转向架样本构架为研究对象,基于其在位使用状态下的动应力进行疲劳损伤与疲劳寿命研究。结合车辆运行状态数据,研究构架关键部位的损伤分布特征,分析构架疲劳损伤快速累积的原因。针对样本构架关键部位：计算其裂纹萌生寿命;基于雨流计数后的应力幅子样完成应力幅分布核密度估计;建立裂纹扩展模型,采用蒙特卡洛法与反函数法计算构架关键部位不同运行里程下的累积失效概率。结果表明,构架累积失效概率随运行里程增加而快速增加,裂纹萌生后对应于97.5%可靠度的运营里程为3万km;构架疲劳寿命为裂纹萌生寿命与扩展寿命之和,97.5%可靠度下为48.39万km。研究结果为进一步提升构架抗疲劳设计、优化转向架检修周期提供研究基础。     

P-S-N曲线的Bootstrap置信带

由小子样疲劳试验数据估计出的疲劳可靠性设计P-S-N曲线可能偏于危险,目前常采用C-P-S-N(置信度-可靠度-应力-寿命)曲线提高预测结果的可信性,文中基于Bootstrap方法提出一种新的估计C-P-S-N曲线的方法.给出所提方法的具体实现,所提方法借助Bootstrap再抽样技术,可以拟合任意置信度和任意可靠度下的C-P-S-N曲线,并获得更安全可信的估计结果,有效改善常规方法出现的危险问题.采用所提方法对材料LY12CZ铝合金板材疲劳试验数据进行分析讨论,结果表明所提方法是合理可行的.     

离心式叶轮的概率失效分析

以概率论和断裂力学为基础,考虑参数的不确定性和随机性,应用蒙特卡洛方法对再制造叶轮的疲劳寿命进行分析。结果表明,采用蒙特卡洛方法进行的一定可靠度和置信度下的寿命预测反映了参数的不确定性,较传统的断裂力学计算结果更安全;初始裂纹尺寸、断裂韧性、变异系数、气动载荷对疲劳扩展寿命的影响较大;将概率断裂力学应用于叶轮的疲劳寿命预测中,为相关叶轮的设计、检修提供了参考。     

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.     

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....     

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.