基于弹性结构的轨道车辆振动分析

利用Simpack和Ansys软件建立了车辆系统刚柔混合动力学模型,分析了车体和构架的固有模态。将车体和转向架构架视为弹性结构,计算了不同的弹性结构组合对车体平稳性以及安全性等车辆运行品质的影响。研究表明,弹性结构对车辆的动力学指标影响较大。在研究车体平稳性时需将车体考虑成弹性,车体的一阶弯曲振动对车体振动影响最明显,而构架可作刚性结构处理。在研究车辆的安全性能时构架需要考虑成弹性结构,而车体则可视为刚性结构。     

120km／h电力机车车体疲劳强度评定方法研究

针对机车车体结构的特征,引进了一种可以对机车车体结构的疲劳强度进行评估的新方法——抗结构疲劳储备系数计算法,该方法以有限元计算的应力幅和平均应力为基础,考虑了疲劳缺口系数和平均应力影响系数对计算的影响。最后以120km／h电力机车车体为工程应用实例,应用投影法将车体结构的多轴应力转化为单轴应力,利用修正Goodman曲线评估法验证了抗结构疲劳储备系数计算法的有效性。     

基于垂向运行平稳性的高速列车参数设计

针对高速列车车体结构等效载荷与结构模态之间的强耦合特性使车体在运行过程中产生弹性振动,影响客车运行平稳性问题,基于柔刚耦合动力学原理,建立了客车垂向动力学模型,计算了系统响应功率谱,分析了车辆悬挂参数和运行参数对振动的影响。仿真发现弹性车体振动响应大于刚性车体,车体1阶垂弯振动对弹性振动的贡献最大,速度越高,对1阶垂弯频率要求越高,提高车体结构阻尼和1系垂向阻尼、适当降低2系垂向阻尼可提高车体垂向运行平稳性。     

25T客车车体结构轻量化研究

以25T型客车碳钢车体为研究对象,对车体结构进行尺寸优化分析。首先,在给定的静强度计算工况下,通过灵敏度分析,确定了对体积和应力影响较大的车体结构;然后,以应力作为约束,以车体结构重量为优化目标,对部分结构板厚进行优化,并对得到的理论优化板厚进行圆整处理;在尺寸优化结果的基础上,结合25T车体结构受力特点,拟定了三种优化方案,并对三种优化方案进行了强度、刚度和减重效果的对比分析,最终确定了车体的最优化方案。     

车体设计参数对车体垂向弯曲振动频率的灵敏度分析

采用基于灵敏度分析的车体垂向弯曲刚度优化方法,对车体结构关键参数进行了灵敏度分析,确定了关键设计变量与系统响应的关系,从而得到了结构设计变量（车体结构关键参数）对目标约束函数（车体一阶垂向弯曲振动频率）影响的变化梯度。首先,由欧拉-伯努利梁垂向振动微分方程,结合初始条件和边界条件,得到了自由梁的一阶垂向弯曲振动频率方程;然后,结合车体结构特征,推导和修正了车体的一阶垂向弯曲振动频率解析方程,并以某地铁车体对解析方程进行了有限元的验证;最后,选取车体的6组设计参数进行了车体一阶垂向弯曲振动频率的灵敏度分析。根据研究结果,给出了车体关键参数对其一阶垂向弯曲振动频率影响程度的排序,为列车车体设计相关工作提供了参考依据。     

基于25%小偏置正面碰撞的某乘用车前端结构改进设计

对比分析25%小偏置正面碰撞车体结构变形与正面全宽和40%偏置碰撞车体结构变形异同点。针对小偏置碰撞车体结构变形特点提出车体前端结构优化措施,优化措施包括结构改进与材料加强两个方面。对优化后的整车模型进行25%小偏置碰撞虚拟实验,结果表明车体结构优化效果显著,乘员舱侵入量明显减小。进行了正面全宽和40%偏置碰撞工况下的减速度波形验证,证明改进整车模型刚度配置合理,不会影响乘员约束系统的匹配。     

中白货运1型机车车体结构研究

介绍了中白货运1型机车车体的结构特点、参数,阐述了车体主要部件的结构,并对车体结构进行了强度计算分析,计算结果表明,车体结构强度满足要求。     

高速列车有限元参数化

铁路车辆的性能一直都是运输行业的重要课题,对于车辆的研究会影响到整个铁路交通的发展。将列车车体分成底架、侧墙、车顶等几个模块,每个模块都有自己的子模块,将车体结构模块细化到钢板、槽钢等板材结构,用有限元软件ANSYS的参数化语言APDL语言,对车体模型以命令流的形式表示,最终达到对车体结构模型参数化,方便车体结构优化,有利于对车体进行有限元仿真分析,提高车体建模分析效率,缩短车体技术更新时间,并且有助于技术交流。     

铁路客车车体轻量化问题的研究

在车辆轻量化的过程中,车体承载结构的轻量化显得尤为重要。车体承载结构的轻量化,要保证车体的强度、刚度和动态特性等满足提速客车的要求。文中利用ANSYS软件建立25K型硬卧客车车体轻量化前后的有限元模型,计算车体的强度、刚度和模态,并对轻量化前后的车体作对比分析;然后,用NUCARS动力学分析软件建立25K型硬卧客车系统的数学模型,分析弹性振动对平稳性的影响,并就刚性车体模型和轻量化前后的弹性车体模型对平稳性和加速度响应的影响作对比分析。     

上弦梁刚度对机车车体强度和刚度的影响分析

采用有限元方法分析上弦梁刚度对通用型窄轨内燃机车车体结构强度和刚度的影响,结果显示,上弦梁刚度对车体各部分的影响是不同的:上弦梁刚度的增加,会增加车体司机室结构的最大等效应力,而降低底架结构的最大等效应力和底架与边梁的挠度.     

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.