惯性导航平台减振装置设计及其动态特性分析

针对惯性导航平台隔离振动的要求,在分析惯性导航平台振源基础上,结合减振理论,设计了该平台的减振系统。基于复刚度模型的橡胶减振系统理论,实验测试得到橡胶减振器多种工况下的参数-刚度、损耗因子。建立了减振系统的有限元模型,通过模态分析获得减振系统的前12阶固有频率,并通过谐响应分析方法分别获得发动机怠速激励和陀螺仪抖动激励下的位移响应,结果表明所设计的减振系统固有频率远离发动机怠速激励和陀螺仪抖动激励频率、位移响应幅值小,具有良好的减振效果。     

激光陀螺仪定位系统支架结构及其动态设计

针对激光陀螺仪定位系统研制中,因支架结构不合理及动态性能差而出现的系统输出数据误差大和死机等问题,在分析研究原支架基础上,对陀螺仪支架重新进行结构设计和动态设计,通过对支架模型的多次修改和重分析,得到最后的设计结构.试验验证,计算结果与试验结果有较好的一致性.新支架结构合理,其固有频率远离陀螺仪抖动器工作频率,陀螺仪安装面的相对振幅降低到最小.经现场测试检验,新支架应用于定位系统后,陀螺仪工作正常,输出数据好,系统定è位精度达到设计要求.本文提出的动态设计方案,对精密电子设备机械部分的动态设计有参考价值.     

振动CAE分析在空调压缩机支架设计中的应用

基于有限元分析方法分析空调压缩机系统模态,并通过分析引起振动的激励源.找出压缩机支架和安装螺栓断裂的根本原因,并根据分析提出了解决措施.     

VVVF电梯系统试验模态分析

乘坐舒适性是电梯系统的重要技术指标 ,模态分析是研究机械系统动态特性的主要方法之一。本文介绍了试验模态分析理论 ,VVVF电梯试验模态分析系统的组成 ,以及试验结果 ,并对电梯系统的设计和安装提出了改进意见     

激光陀螺系统动力学特性分析

在构建激光陀螺捷联系统时,由于三个激光陀螺安装在同一个支架上,并且三个陀螺振子都在进行高频角振动,激励支架产生耦合振动,外界的干扰振动也会通过隔振器传到支架上,因此造成陀螺是在振动载体环境下工作,引起激光捷联系统的振动耦合误差,导致系统导航精度下降。采用MSC.NASTRAN有限元软件,分析了某激光陀螺系统的动力学特性和振动模态,确定了三个激光陀螺的合理安装位置。计算了隔振器的隔振效果,并分析了外界扰动对激光陀螺的影响。由此评估激光陀螺系统的动力学特性,得出其中存在的弱点,为激光陀螺系统结构的动力学特性修改提供依据。     

平台罗经方位环结构实验模态参数识别

平台罗经是惯性导航系统中的一种精密复杂的导航仪器,平台罗经的核心部件方位环的动态特性直接决定着惯性仪表的工作精度和可靠性,模态分析是研究机械系统动态特性的主要方法之一。在概述了实验模态分析理论的基础上,建立了某型号平台方位环结构的实验模型,对方位环进行了实验模态分析。通过对实验结果与有限元计算结果比较,验证了有限元计算结果较为准确。     

基于模态分析的某产品安装支架设计优化

以模态分析的相关理论为依据,基于某产品安装支架的结构特点,应用有限元软件建立仿真模型,进行模态分析;通过考察应变能云图找出安装支架设计中应重点关注、需进行改进的区域;同时通过对支架结构的单元密度云图分析,找出安装支架在受冲击载荷作用下的主要传力路径;针对性的进行结构设计改进,提高安装支架刚度,为同类产品安装支架优化设计提供了参考依据。     

雷达天线系统机械结构的动力分析与实验研究

本文采用改造的自由界面模态综合技术分析了某舰载雷达天线、天线座系统机械结构的动态特性和动力响应。获得了系统的低阶固有模态和基础激励(正弦和阶跃)下动应力分布。其与实验模态分析和时序分析的结果相符,研究结果为改进结构设计、提高结构谐振频率,提供了重要价值的意见。     

某微型客车车身模态分析

采用Hypermesh软件建立了某微型客车白车身有限元模型,通过optistruct对该模型进行自由模态分析计算,得到了白车身的各阶模态频率和模态特性。对模态分析结果与汽车内外部的激励源频率特性进行了较为详细的分析,为该车的动态特性改进设计提供参考。     

安装中央制动器的变速器后壳改进设计与仿真

为了满足直接安装中央制动器的要求,对原有变速器后壳进行了结构改进设计,并利用有限元法校核了改进后的壳体静力学强度与刚度.通过模态仿真分析,比较了原方案与改进后方案的模态振动特性.分析结果表明,改进后的壳体能承受制动器制动力矩的作用而不会发生损坏,自由模态频率较原方案略有提高,约束模态频率远高于变速器受到的激振频率.该变速器后壳具有良好的静态、动态特性,满足实际使用需求.     

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.