磁流变半主动起落架的落震仿真分析

建立了冲击载荷下磁流变减震器力学模型,并用试验数据验证了该模型有较高的准确性与可信度。在ADAMS/Aircraft中建立了基于磁流变减震器的飞机主起落架虚拟样机模型,并在MATLAB/Simulink中搭建了磁流变半主动起落架的模糊控制系统。应用ADAMS和MATLAB软件,对飞机两点着陆情况下的磁流变半主动起落架的落震过程进行联合仿真分析,并对比被动控制和半主动控制起落架的仿真结果。研究结果表明,磁流变半主动控制起落架能够有效地降低飞机落震冲击载荷和振动响应。     

基于ADAMS的磁流变减震器起落架仿真模块开发

建立基于ADAMS的磁流变减震器起落架仿真模块,可以更加方便的进行飞机起落架的动力学仿真。通过ADAMS/View的二次开发功能,在ADAMS/View里建立基于磁流变减震器的起落架参数化模型,进行界面设计并完成模型与界面的数据链接,建立一个针对磁流变减震器的起落架落震仿真的专用分析模块。     

基于磁流变减震器的弹性机体起落架着陆仿真分析

该文针对自行设计的多环形槽结构磁流变减震器,建立了减震器力学模型。以某支柱式起落架飞机为原型,在MSC ADAMS/Aircraft平台上建立起落架及全机虚拟样机模型,分别进行弹性和刚性机身全机着陆动力学仿真试验。仿真结果表明,考虑机身弹性的落震试验结果更准确,而所设计的磁流变减震器在合适的励磁电流作用下减震效果理想,能够满足飞机着陆性能的要求。     

飞行器柔性起落架落震性能分析

以某型飞行器为原型,对该型飞行器进行了起落架缓冲器参数设计,并建立适用于ADAMS/Aircraft软件的起落架着陆性能仿真三维数字模型。进行了全刚性起落架全机落震仿真,验证起落架缓冲器初步设计结果基本满足落震缓冲性能要求。运用有限元软件对刚体起落架模型进行了柔性化处理,把起落架柔性因素考虑到缓冲性能分析中,建立简化数学模型对仿真结果加以分析验证。得出起落架柔性对缓冲器性能有一定影响的结论,并指出其影响的原因。对缓冲器参数设计具有指导意义。     

H_∞理论在起落架半主动控制系统中的应用

以某型双腔式起落架为研究对象,建立了起落架着陆动力学方程,应用ADAMS软件构建该起落架的虚拟样机模型,在考虑控制对象模型的不确定性和系统干扰抑制的情况下,基于混合灵敏度问题求得鲁棒H∞控制器。应用ADAMS及Matlab/Simulink软件,对半主动起落架的落震仿真过程进行实时控制,进行机械系统和控制系统的联合仿真分析,并对比被动控制和半主动控制起落架的仿真结果。对比研究结果表明:半主动控制起落架能够有效地降低直升机着陆时的冲击载荷和振动响应,从而提高直升机着陆的安全性和舒适性。     

飞机起落架缓冲性能仿真分析

以某型飞机摇臂式主起落架为例,介绍了基于Motion和AMESim的起落架缓冲性能联合仿真研究方法.结合实际情况,首先利用LMS Virtual Lab Motion建立了多体动力学分析模型,然后根据缓冲器参数建立LMS Imagine Lab AMESim缓冲器液压模型,最后通过两个软件的联合,仿真计算了某型飞机主起落架的缓冲性能.通过对缓冲器参数的调整,优化了缓冲器设计,为起落架的落震试验奠定了理论基础.提供了一个研究起落架缓冲性能的新方法,试验结果表明,该方法是可行并有效的.     

大型民用飞机起落架应急断离分析与仿真

起落架应急断离设计是民用飞机设计中必须考虑的问题。根据适航相关规定,论述了起落架应急断离设计的结构设计要求。基于LMS Virtual.Lab Motion多体动力学仿真平台,建立了某型民用飞机主起落架的动力学仿真模型。完成主起落架自由落震、地面滑跑过障碍物等情况的仿真计算,并着重对仿真过程中各断离点载荷进行分析,确定了相应的断离载荷和断离序列,实现了大型民用飞机起落架应急断离动力学特性的分析与仿真。     

基于有限元柔性体理论的起落架落震仿真分析

以某飞机起落架为研究对象,研究落震动力学问题。根据前起落架的结构特性,利用多体动力学建模技术,建立前起落架多柔性体动力学（MFBD）模型,并进行落震仿真分析及非线性接触研究。采用落震试验数据对模型进行校验,仿真结果与试验数据较为吻合。通过分析缓冲器零件的变形,考虑接触因素的多柔体动力学模型能更真实反应实际情况,以最大降落速度工况进行落震仿真,同时对起落架关键零件进行强度校核,以及缓冲器内部零件进行非线性接触计算,求得不同材质的下凸轮及底托受到的垂向力与摩擦力,获得在物理试验中难以测量的数据,分析结果对起落架设计具有重要意义。     

基于虚拟样机技术的飞机地面运动多学科协同仿真

将多学科协同仿真技术应用于飞机地面动力学研究,以ADAMS/Aircraft软件的多体动力学建模为核心,联合CATIA软件生成飞机和起落架几何构件,联合PATRAN/NASTRAN软件进行模态分析生成柔性体,联合MATLAB软件建立控制系统模型,采用落震与静力试验的结果校核模型,然后对飞机地面滑跑转弯、防滑刹车、摆振等运动进行多学科协同仿真。结果表明,该仿真模型能准确模拟飞机的地面运动,并得到一些有意义的结论。     

飞机弹射起飞起落架动力学仿真分析

基于多体系统动力学的方法理论,应用ADAMS软件建立前起落架和主起落架的动力学仿真模型,并且以此为基础建立全机的动力学虚拟样机模型,对飞机弹射起飞过程进行仿真分析,并针对不同飞机起飞质量和弹射力,对比分析了其对起落架动力学响应及全机起飞性能的影响,结果表明:应用ADAMS对飞机起落架结构进行动力学仿真分析对起落架设计能提供必要的依据,减小飞机起飞质量以及增大弹射力,能够有效提高飞机弹射起飞性能。     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.