飞行器折叠翼机构展开性能的优化及实验

为了优化飞行器折叠翼机构的展开性能,对飞行器的折叠翼机构进行分析,并提出了优化其展开性能的方法。建立了折叠翼机构展开的理论模型和动力学仿真模型,对折叠翼机构展开过程进行了动力学分析,并进行了实例计算。分析了影响折叠翼机构展开性能的因素,用正交试验的方法对折叠翼机构进行了优化设计,得到了最优折叠翼机构方案,并对最优方案进行了仿真分析。最后,按照最优方案折叠翼机构进行了改进,实验测试了折叠翼机构的展开性能。实验测得折叠翼机构展开时间为0.128s,测点位置应力分别为82 MPa和92 MPa;动力学仿真得到折叠翼机构展开时间为0.122s,相应测点位置应力分别为85MPa和96MPa,两项测试误差在5%以内。得到的结果表明折叠翼机构满足机翼展开稳定、快速,应力和冲击力小的要求,为飞行器性能的调高奠定了基础。     

“一字型”折叠翼展开机构的参数优化设计与分析

根据"一字型"折叠翼的工作原理与性能要求,确定折叠翼展开机构的关键设计参数和影响程度,建立折叠翼展开机构各参数的数学描述模型。利用MATLAB软件求解各尺寸参数与展开时间、燃气作动筒摆动角和传动效率之间的影响关系。以展开时间、燃气作动筒摆动角和展开机构传动效率为目标,以各尺寸参数为变量,采用线性加权和法对折叠翼各参数进行优化设计,从而获得折叠翼展开机构的最优设计参数,为折叠翼展开机构的后续设计提供依据。     

无人机折叠翼展开动力学分析

折叠翼的展开性能关系着箱式发射无人机在发射后能否正常的飞行。以箱式发射无人机折叠翼为研究对象,根据其结构及工作原理,建立展开机构运动的微分方程;利用LMS Virtual.Lab建立展开动力学模型,分析机翼在不同扭簧刚度下的展开过程,得到机翼展开角度、角速度、角加速度和冲击载荷曲线;利用橡胶进行减振并探讨阻尼系数对减振效果的影响。结果表明:机翼能够在设计要求的时间内展开到位并锁定,加入橡胶后的冲击载荷降低了46.7%,随着橡胶阻尼系数的增加,振动逐渐减弱。     

基于ADAMS/Insight的折叠翼展开机构工作可靠性仿真

利用机械系统动力学分析软件ADAMS作为机构工作可靠性分析平台,建立折叠翼展开机构的参数化模型,确定在ADAMS/Insight模块下折叠翼展开机构的工作可靠性仿真流程。在综合考虑其机构尺寸误差、运动副间隙误差及驱动力峰值误差的基础上,进行可靠性仿真试验,并得到仿真试验结果。基于所建立的折叠翼展开角位移、展开时间及锁紧销冲击力可靠度理论模型进行可靠度计算,实现了对折叠翼展开机构工作可靠性的评估与分析。     

空间凸轮-螺旋组合式折叠翼面展开机构设计及其运动特性分析

提出新型空间凸轮—螺旋组合式折叠翼面展开机构,分析其工作原理,确定其相关技术参数。基于解析法与反转法,对折叠翼面展开机构的功能执行部件———空间圆柱凸轮机构进行了运动规律设计和包括凸轮槽道廓线、压力角及廓线曲率半径的设计,建立了折叠翼面展开机构展开运动学理论模型并进行了求解,结果证明折叠翼面展开机构符合设计要求,其运动规律设计正确。     

考虑铰间隙的折叠翼展开机构展开过程碰撞动力学仿真分析

基于“二状态模型”的非线性等效弹簧阻尼模型,建立折叠翼展开机构的铰间隙碰撞模型,利用ADAMS软件对折叠翼展开机构的展开过程动力学进行仿真分析．包括间隙大小和间隙摩擦在折叠翼展开机构展开过程中引起的碰撞力变化规律。结果表明,在折叠翼展开机构整个展开过程中,由于间隙的影响,产生随机持续的碰撞力;随着间隙增大,碰撞次数减少,碰撞力幅值有增大的趋势;摩擦加快系统能量的损耗,一定程度上抑制了间隙碰撞次数和展开机构动力学扰动效应。     

折叠翼展开机构测试装置设计与试验验证

基于折叠翼展开机构的工作原理和功能需求,确定了折叠翼展开机构性能参数测试方法,完成了其测试装置的设计及原理样机研制。应用所研制的折叠翼展开机构测试装置进行折叠翼展开性能试验,获得其各项性能指标,并通过不同转矩下折叠翼展开机构测试装置试验,分析其性能参数变化规律。结果表明：弹翼能迅速展开到位,锁紧销与过位挡块能实现翼面准确定位、可靠锁定,且展开过程中各部件之间相互无干涉,满足设计要求。     

考虑共因失效的折叠翼展开机构可靠度分析

共因失效问题是系统可靠性研究的重要内容之一,而在目前的机构运动可靠性分析中往往忽略了共因失效效应。由于影响机构运动的外部因素(载荷)与机构运动参量(运动所需时间)是不同量纲的物理量,因此目前还没有类似于"应力-强度"干涉模型这样简单有效的机构可靠度模型。通过试验与仿真相结合的方式建立折叠翼展开机构虚拟样机,并用Monte-Carlo仿真方法验证了多组折叠翼展开机构组成的系统存在共因失效现象,提出一种新的考虑共因失效效应的机构系统可靠度模型。新模型根据概率统计平均的意义重新解释了两个随机变量干涉分析的基本概念,并将其拓展为给定风速下的折叠翼展开机构条件可靠度的随机风速加权平均模型,从而得到单个折叠翼可靠度计算模型。又因为在确定的风速下系统中各折叠翼展开时间为独立同分布随机变量,将系统中各折叠翼条件可靠度在全部可能的风速范围内进行统计平均即可得到机构系统可靠度模型。算例分析表明新模型可以在考虑共因失效的条件下精确计算展开机构系统可靠度,并且在应用时只需要得到几个确定性风速下展开时间的分布来预测系统可靠度,便于工程应用。     

舵机折叠翼展开性能及实验

为了研究某导弹舵机的折叠翼机构的展开性能,对该机构展开性能进行研究。首先,基于第二类拉格朗日方程建立了机构的动力学方程,为仿真提供理论依据。然后,利用MSC.Adams软件对机构的展开过程进行刚柔耦合动力学仿真,得到了展开时间、冲击载荷、应力等数据。最后,对实物进行展开实验,测试了展开特性以及冲击载荷对薄弱环节的影响。实验结果表明,展开时间为175 ms,冲击载荷为42.9 N,舵片应力5.49 MPa,小于材料的屈服强度325 MPa,满足设计要求。仿真模型准确地反映了机构的展开过程,仿真与实验的结果可以为结构设计及优化提供理论的依据。     

“一字型”折叠翼展开试验与仿真验证分析

以某"一字型"折叠翼展开机构为研究对象,应用研制的折叠翼展开试验装置,进行了不同转矩下的展开试验,得到了其关键性能参数变化规律。参照"一字型"折叠翼展开机构原理样机的实际几何参数、物理特性及约束条件,在ADAMS中建立其虚拟样机模型,通过仿真分析得到了对应驱动力下折叠翼的运动参数和展开性能参数的变化规律。对比分析仿真与试验结果可知:弹翼能及时展开到位,准确定位、可靠锁定,且展开过程中各部件之间无干涉,满足设计要求。     

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.