可伸缩机翼结构设计与振动实验研究

对一种可伸缩机翼实验装置进行结构设计、功能实现和振动实验进行研究利用三维建模软件优化设计了可伸缩机翼的作动机构,完成对可伸缩机翼结构的总体设计和各个子系统结构设计,基于可伸缩机翼实验装置进行了振动实验研究,详细分析了在不同的外伸速度和收缩速度情况下,可伸缩机翼的横向振动响应,得到有意义的实验结果,对工程应用具有一定的理...     

三维散斑相关法在机翼变形动态测量中的应用

针对机翼变形中应变检测的常规方法和传统方法存在的不足,以及飞行过程中的动态性和实时性要求,对基于三维散斑相关的机翼变形动态测量方法进行了研究.首先,由数字散斑相关和双目立体视觉的基本理论出发介绍了机翼动态三维变形测量方法;然后,针对散斑图像特点,分别从实时性、匹配基元、匹配准则、算法结构几方面进行分析研究,设计出适合于散斑图像特点的区域立体匹配算法;最后,构建出系统布局,并通过实际制作机翼模型进行验证.经分析,实验数据能较好地反映机翼变形过程中的三维应变状态.进而验证了该方案及算法的可行性.     

变截面Z型折叠机翼振动特性的有限元与实验分析

Z型变截面折叠机翼作为一种可变体机翼结构,不同的折叠角对机翼稳定性有着重要的影响,因此研究不同折叠角度下的特性参数对机翼动态稳定性有着重要的意义.本文首先设计加工了Z型变截面可折叠机翼结构的实验模型,通过建立与实验模型相匹配的有限元模型,仿真得到不同折叠角度下机翼的前5阶固有频率和振型,针对不同折叠角度下机翼的固有特性,通过扫频实验得到机翼前5阶固有频率和模态振型,以及横向外激励作用下三段翼的频响曲线,对比分析有限元仿真与实验结果,验证结果的可靠性,这将对机翼结构设计以及特性参数的选取提供参考依据.     

变截面Z型折叠机翼振动特性的有限元与实验分析

Z型变截面折叠机翼作为一种可变体机翼结构,不同的折叠角对机翼稳定性有着重要的影响,因此研究不同折叠角度下的特性参数对机翼动态稳定性有着重要的意义.本文首先设计加工了Z型变截面可折叠机翼结构的实验模型,通过建立与实验模型相匹配的有限元模型,仿真得到不同折叠角度下机翼的前5阶固有频率和振型,针对不同折叠角度下机翼的固有特性,通过扫频实验得到机翼前5阶固有频率和模态振型,以及横向外激励作用下三段翼的频响曲线,对比分析有限元仿真与实验结果,验证结果的可靠性,这将对机翼结构设计以及特性参数的选取提供参考依据.     

形状记忆合金力学性能及在变体结构中的应用研究

形状记忆合金（Shape Memory Alloys,SMA）由于其特有的形状记忆效应（Shape Memory Effect,SME）被大量研究和广泛应用。基于SMA的Müller-Achenbach-Seelecke模型进行了单根SMA丝的回复力数值计算验证,并设计了一种SMA丝驱动器应用于机翼变后掠角结构中,完成了机翼连续后掠偏转的原理、方案和具体的结构设计,并加工制备了后掠机翼模型;同时为了实现机翼后掠角变化的精确控制,采用PID控制方法设计了SMA温度与偏转角度双路信号反馈的闭环控制系统,完成了对机翼偏转的控制。实验结果表明,机翼可实现45°的偏转,偏转至设定角度后的平均稳态误差控制在±0.3°以内,实现了对偏转角度的精确控制。     

关联设计技术在机翼盒段快速建模中的应用

飞机等复杂产品设计过程日趋全三维化,三维模型的准确快速创建和维护成为影响 产品设计周期的重要因素。零件快速建模方式只能针对单个零件进行快速建模,无法实现相关联 零件的快速修改及自动更新。关联设计技术的提出使得针对装配体的快速建模和快速修改成为可 能,从而进一步提高机翼设计效率。针对这种现象深入研究关联设计技术及快速建模方法的结合, 给出了结合关联设计技术的机翼盒段快速建模的具体方法,并开发机翼盒段快速建模工具对装配 体快速建模的方法进行验证。     

仿生扑翼“0”形轨迹机构的设计及气动力特性

针对仿生扑翼飞行器的驱动结构进行设计,提出了一种空间摇杆式的驱动机构与机翼扭转机构,实现机翼扑动过程中的"0"形空间运动轨迹.针对机翼的空间"0"字形运动,建立仿生飞行器气动分析模型,采用动网格与非定常数值计算方法,对机翼拍动过程中不同相位下的升阻特性进行分析,并通过空气动力效率与流场对比分析,得到不同参数条件下的气动效率,为仿生扑翼飞行器的设计及扑动模式的选择提供参考.通过气动力测量实验、台架姿态标定和外场飞行测试,验证了结构设计的合理性.     

三维机织物结构设计软件的设计与实现

三维机织物的织造需要提前绘制其结构,为解决三维机织物结构多样化所带来的设计绘制困难问题,提出一种三维机织物剖面图绘制方法,构建三维机织物结构设计软件的体系框架,阐述软件设计与实现过程。通过Qt5.9实现软件开发,实现了软件设计层、报警层与显示层的功能,实现了三维机织物结构的纱线交织设计绘制,实现了三维机织物三维建模,可满足任意三维机织物结构设计需求,并证明了方法可行性。     

三轴稳定卫星的三维数字仿真平台的设计

虚拟现实技术是仿真领域的一个重要发展方向，将它引入卫星领域，实现卫星运动的可视化可以提高设计人员的工作效率。本文介绍了一个基于OpenGL的三轴稳定卫星的三维数字仿真平台的设计。它将卫星的三维仿真分为姿态仿真和轨道仿真，并详细描述了它们的三维场景及数据流程。然后选择了软件工具，并对软件进行了总体结构设计。     

柔性变形机翼后缘拓扑优化设计

为了实现机翼表面的自适应变形和结构轻量化,将柔件机构引入到机翼后缘形状变化结构设计中.应用连续体拓扑优化技术,以实际位移与目标位移之间的偏差为目标函数,材料用量为约束,建立SIMP(solid isotropic material with penalization)密度刚度插值模型.采用Matlab编程对柔性机构进行了优化设计,并对不同参数下的优化结果进行了讨论,最后进行机构的仿真分析.研究结果显示该柔性机构能够实现预期的形状变化,证明了方法的正确性,为柔性机翼设计提供理论基础.     

Robust evolutionary algorithms for UAV/UCAV aerodynamic and RCS design optimisation

One of most important challenges in Unmanned (Combat) Aerial Vehicles (UCAV) is improvement of survivability and that can be achieved by well designed aerodynamic and Radar Cross Section (RCS) shapes. The aerodynamic efficiency aims to providing a short distance take-off, long endurance and better maneuverability. In addition, the stealth property is one of the essential requirements to complete diverse missions and ensure the survivability of UAVs. This paper explores the application of a robust Evolutionary Algorithm (EA) for aerofoil sections and wing plan form shape design and optimisation for the improvement of aerodynamic performance and the reduction of Radar Cross Section. The method is based on a canonical evolution strategy and incorporates the concepts of hierarchical topology, parallel computing and asynchronous evaluation. Results obtained from the optimisation show that utilising the designing transonic wing aerofoil sections and plan form in combination with evolutionary techniques improve the aerodynamic efficiency. It is shown that this optimisation procedure produced a set of shock-free aerofoils and achieved supercritical aero-diamond wings. Results also indicate that the method is efficient and produces optimal and Pareto non-dominated solutions.     

A generalized “max-min” sample for surrogate update

The preliminary Multidisciplinary Design and Optimisation of a flexible wing aerofoil apropos a small Unmanned Air Vehicle is performed using a multifidelity model-based strategy. Both the passively adaptive structure and the shape of the flexible wing aerofoil are optimised for best aerodynamic performance under aero-structural constraints, within a coupled aeroelastic formulation. A typical flight mission for surveillance purposes is considered and includes the potential occurrence of wind gusts. A metamodel for the high-fidelity objective function and each of the constraints is built, based on a tuned low-fidelity one, in order to improve the efficiency of the optimisation process. Both metamodels are based on solutions of the aeroelastic equations for a flexible aerofoil but employ different levels of complexity and computational cost for modelling aerodynamics and structural dynamics within a modal approach. The high-fidelity model employs nonlinear Computational Fluid Dynamics coupled with a full set of structural modes, whereas the low-fidelity one employs linear thin aerofoil theory coupled with a reduced set of structural modes. The low-fidelity responses are then corrected according to few high-fidelity responses, as prescribed by an appropriate Design of Experiment, by means of a suitable tuning technique. A standard Genetic Algorithm is hence utilised to find the global optimum, showing that a flexible aerofoil is characterised by higher aerodynamic efficiency than its rigid counterpart. Wing weight reduction is also accomplished when a Multiobjective Genetic Algorithm is adopted.     

Selected Engineering Applications of Gradient Free Optimisation Using Cuckoo Search and Proper Orthogonal Decomposition

This paper discusses some engineering applications of gradient free optimisation techniques. This is achieved using the development of the cuckoo search algorithm as a case study. The motivations behind using gradient free algorithms are discussed and illustrated using two specific practical examples. The first involves aerofoil shape optimisation, where it is shown that a modified cuckoo search algorithm performs well when applied both to aerofoil inverse design and aerofoil shape optimisation. This example is then used to discuss the use of reduced order modeling to decrease the computational cost of the optimisation process. We discuss which reduced order modeling techniques based on proper orthogonal decomposition are suitable for these optimisation applications. The second example is that of co-volume mesh optimisation, where it is shown that a modified cuckoo search can significantly outperform alternative non-optimisation and gradient based techniques. We conclude by discussing a number of remaining difficulties which may deter engineers from using gradient free techniques, and suggest ways in which these may be alleviated.     

CAD-based shape optimisation using adjoint sensitivities

Existing approaches to CAD-based design optimisation using adjoint sensitivities are reviewed and their shortcomings are recalled. An alternative approach is presented which uses the control points of the boundary representation (BRep) as design parameters. The sensitivity of the objective function with respect to the design variables is calculated using automatic differentiation (AD). Results for a 2-D aerofoil are presented.     

动态信号波形采集及其应用研究

以冀型风洞为对象,着重介绍了变湍流度对冀型转捩因子影响的速度脉动波形采集的原理和方法,重点对波形采集系统用户界面的设计、定时器的应用、分页显示和连续显示等技术进行了具体介绍,并给出了实验结果及分析。     

基于MSC Nastran的机翼振动抑制技术研究

利用MSC Nastran开发语言DMAP(Direct Matrix Abstraction Program),基于现代控制理论,建立机翼有限元结构的振动控制模型,并使用线性二次型最优控制理论对机翼结构进行振动抑制研究. 根据MSC Nastran对于大型稀疏矩阵强大的求解功能,有效地实现主动控制方法在大型有限元结构上的应用,并取得很好的控制效果.     

基于CAN总线的网络化汽车传感器的研究与设计

网络化传感器是传感器发展的又一方向。讨论了全控制局域网(CAN)网结构,介绍了网络化汽车传感器的设计,给出了设计的总体框架和基本结构。详细地讨论了汽车传感器CAN网络接口的设计,结合具体的硬件结构框图和电路图来说明接口软件的实现。该设计方案具有很强的通用性。     

可重构密码协处理器的组成与结构

文章提出了一些关于可重构密码协处理器的组成与结构的设计思想和方法。可重构密码协处理器组成与结构是指可重构密码协处理器的组成模块及其相互之间的连接网络。可重构密码协处理器组成与结构的设计直接影响到可重构密码协处理器的性能,因此是可重构密码协处理器设计中的一个关键问题。     

Shape optimisation of preform design for precision close-die forging

Preform design is an essential stage in forging especially for parts with complex shapes. In this paper, based on the evolutionary structural optimisation (ESO) concept, a topological optimisation method is developed for preform design. In this method, a new criterion for element elimination and addition on the workpiece boundary surfaces is proposed to optimise material distribution. To improve the quality of the boundary after element elimination, a boundary smoothing technique is developed using B-spline curve approximation. The developed methods are programmed using C# code and integrated with DEFORM 2D software package. Two 2D case problems including forging of an aerofoil shape and forging of rail wheel are evaluated using the developed method. The results suggest that the developed topology optimisation method is an efficient approach for preform design optimisation.     

一种改进型微带交指滤波器的仿真设计

针对微带交指滤波器KQ法及奇偶模阻抗法设计不够精确、不够简便的问题,研究了一种基于自互电容的终端短路式微带交指滤波器的设计方法,给出了详细的设计步骤及仿真设计实例。提出了一种微带交指滤波器的改进结构,该结构通过在交指滤波器的中间耦合节上增加一段λ0/8的微带线,使滤波器的3 dB带宽从100 MB减小到40 MB,带内抖动减小了2.7 dB,阻带衰减增加了2 dB左右,该仿真结果证明了改进结构的有效性。