基于ABAQUS的起落架结构强度分析方法

文章探索了一种基于ABAQUS的起落架结构强度分析方法。该方法充分考虑了起落架各部件运动关系及传力特点,较为准确地模拟了起落架传力路径,构建了全状态起落架静力仿真计算模型。该方法设计的起落架通过了静力试验考核,证明该方法正确合理,其对起落架结构设计、优化减重等具有一定的指导意义。     

某型飞机起落架收放系统故障分析与设计改进

该文阐述了某型飞机起落架收放系统原理,介绍了该飞机在地面试验中出现起落架收放故障现象,对该故障进行原理分析,通过地面试验将故障原因定位为主起时序电磁阀回油不畅,并对起落架收放系统进行设计改进。     

起落架电液伺服加载系统的设计与实现

该文根据某型民用飞机起落架控制系统地面模拟试验的要求,设计了一套起落架电液伺服加载系统,文中对该加载系统的工作原理进行了分析,给出了其总体方案、液压原理图、控制策略以及试验结果等内容,试验结果表明,该系统具有良好的加载性能。     

起落架载荷脱机校准试验技术研究

应变法是起落架载荷实测的主要方法,载荷校准试验是应变法测载的关键环节,直接决定了载荷实测结果的准确性。随着航空技术不断发展,常规的起落架联机校准方法已经无法满足校准试验要求。针对目前起落架载荷校准实际需求,提出了一套起落架脱机载荷校准试验方法,并将该方法用于某型飞机起落架载荷校准试验。通过与常规方法对比显示,该方法有效提升了试验加载能力、安全性、试验效率,更加精准的模拟了起落架的真实受载,提升了试验精度。     

某型飞机起落架加载系统设计

根据某型民用飞机起落架收放机构地面模拟加载试验的要求,设计了一套起落架电液伺服加载系统。对该加载系统的工作原理进行了分析,给出了总体方案、结构示意图及液压原理图等,并详细介绍了该加载系统的软、硬件组成及特点。试验结果表明,所设计的加载系统自动化程度、可靠性及控制精度高,便于实现对起落架气动载荷的准确模拟。     

一种无人直升机起落架落震动力学建模方法研究

以无人直升机缓冲式滑橇起落架为研究对象，建立起落架系统的落震动力学模型，并对着陆过程进行数值分析，结果表明，所提方法可较为准确地识别无人直升机落震过程的过载与位移变化、起落架缓冲器承载与行程极限等参数，为无人直升机部件设计提供限制条件与约束。此外，该设计方法亦可用于其他直升机起落架的设计定型和试验验证，具有一定的工程意义。     

飞机起落架变行程疲劳试验技术发展综述

飞机起落架疲劳试验技术经历了固定行程、一维变行程、二维变行程、三维变行程等发展阶段。固定行程的疲劳试验简单易行 ,但试验寿命偏长。一维变行程疲劳试验技术应用于垂直安装的支柱式起落架。二维变行程疲劳试验技术解决了起落架支柱安装上存在空间倾斜角的问题。实时三维变行程疲劳试验 ,能更真实地模拟起落架的使用情况 ,同时体现了起落架与相关机体结构一体化设计的思想     

特性材料拦阻系统设计所需的起落架限制载荷确定方法

在特性材料拦阻系统(EMAS)设计中,飞机起落架的安全性既是飞机安全性的重要标志之一,亦是产生拦阻力的重要保障。起落架限制载荷是评估起落架安全与否的重要参数。这些参数因起落架型号不同而异,且掌握在飞机制造商手中,不对外公布。根据我国民用航空规章25部中有关牵引载荷、滑行刹车等条款,以及飞机的机场规划手册建立了飞机起落架限制载荷计算方法;并将该方法计算的限制值与参考文献的限制值进行了对比。该方法可以计算飞机起落架的水平和垂直载荷限制值。该方法已经成功地应用于2011年12月我国进行的一系列EMAS真机验证试验。结果表明该方法能够满足飞机在EMAS中起落架安全性评估的要求。     

舰载机前起落架突伸性能分析与验证

舰载机弹射起飞对前起落架突伸性能要求严格,针对双气腔油气式起落架进行突伸动力学建模,编制程序分析起落架的突伸动态过程。设计了一套弹射起落架突伸试验方案,成功地对前起落架突伸动态性能进行了测试与验证,并对试验过程中的现象进行了分析。分析结果与试验结果符合性好。研究了缓冲器内部结构、充填参数变化对突伸性能的影响,通过优化回油孔直径、缓冲器充气压力、轮胎压力,高低压腔体积比、油针尺寸等参数,可以提高起落架突伸性能。     

基于ADAMS的磁流变减震器主起落架落震仿真研究

起落架落震试验费用昂贵,所以使用仿真技术模拟落震试验的整个过程。应用CATIA建立某型磁流变主起落架几何模型,导入到ADAMS/View中,通过添加地面、约束和施加力,建立某型磁流变起落架落震仿真模型,并对某型磁流变减震器主起落架的落震试验数据进行分析和整理。比较仿真结果与试验结果表明,基于ADAMS建立的某型磁流变主起落架仿真模型可有效描述真实起落架,仿真过程可有效模拟落震试验过程。利用该方法节约了试验成本。     

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.