一种新的柔性蜂窝结构及其在变体飞机中的应用

变体色机要求机翼结构可以光滑连续地变形.机翼的蒙皮要有足够大的面内伸缩变形能力,同时还要有足够的面外承载能力.本文针对后缘变弯度机翼,设计出一种新的柔性蜂窝结构.研究了该柔性蜂窝的面内变形能力和形状参数的关系.仿真分析和试验验证表明,该柔性蜂窝结构具有足够的面内变形能力,变形后仍保持良好的面外承载能力,满足后缘变弯度机...     

一种柔性蒙皮设计技术及其在后缘变弯度机翼结构中的应用

变体飞机可在飞行包线内的不同飞行状态下获得最优气动效能,增强执行多种任务目标的能力,实现变体飞机结构的关键技术之一是柔性蒙皮的设计。本文介绍一种基于可变形蜂窝的柔性蒙皮结构,并研究了这种柔性蒙皮在后缘变弯度机翼结构上的应用,通过仿真分析和全尺寸原理样件地面试验验证,该结构满足真实飞行载荷条件下对变形能力和承载能力的要求。     

零泊松比蜂窝面内拉伸力学响应的有限元模拟

自适应飞行器因其对于不同飞行阶段的空气动力学适应性，逐渐成为航空航天研究的重点领域。可变形蒙皮不仅需要具有良好的面内拉伸变形性能，同时材料结构也需要具有一定的刚度来应对飞行过程中的载荷。本文提出以由高性能工程塑料聚醚醚酮（PEEK）材料制备的折线形蜂窝和U形蜂窝材料作为蒙皮结构，通过数值模拟计算确定柔性蒙皮的面内拉伸变形模式及两种蜂窝材料的形状尺寸参数对其面内拉伸变形力学响应的影响。结果表明，折线形蜂窝和U形蜂窝材料的面内变形模式呈现高度一致性，同时，两者的面内拉伸变形性能与蜂窝胞元长度和高度成正比，而与蜂窝厚度成反比。本文研究结果可为变体结构的设计与制备提供理论支持。     

自适应机翼翼型变形的研究现状及关键技术

自适应机翼具有巨大的应用潜力,是未来飞机设计的必然趋势,已经得到了广泛的关注。分别从自适应变弯度前缘、自适应变弯度后缘以及变厚度机翼三个方面阐述了其变形原理,并对使用的蒙皮、驱动方式、研究方法等进行了归纳总结,指出了未来的发展趋势,提出了自适应机翼亟需解决的关键技术,包括兼具大变形和高承载功能的柔性蒙皮的设计、自适应驱动系统设计、协同控制系统的设计、分布式传感器网络,可为自适应机翼结构的设计与实现途径提供一定的技术参考。     

柔性变弯度后缘机翼的风洞试验模型优化设计

本文通过优化的方式设计了一种具有较高变形精度的适用于变体飞行器的柔性后缘变弯度装置。该装置通过结构的弹性变形传递力和运动，包括驱动器、一体成型的蒙皮与梁结构组成。在给定的结构拓扑形状下，为了寻找到最优的驱动、结构参数，本文系统化地提出了柔性变弯度后缘的设计框架。该设计框架包括了变弯度机翼外形参数化方法、变弯度气动外形的优化设计方法和结构参数优化方法，求解结构变形时考虑了几何非线性大变形，采用最小平方误差和考虑空间顺序的Fréchet距离来衡量后缘真实变形与目标变形之间的相似性。对比研究表明，最小误差距离不能捕捉到局部的噪声，而Fréchet距离可以很好地控制最大的变形误差，所需迭代次数较少，并能获得整体变形精度较高的结果。数值仿真验证了所提出的优化方法的有效性。本文对多种具有不同拓扑的初始结构进行参数优化，最大能提高91%变形精度。最后，利用增材制造技术实现了柔性变弯度后缘翼段，该部件具备下偏22.5°,上偏7.5°的变形能力。     

十字形柔性蜂窝的面内切变模量分析方法

介绍了一种具有十字形拓扑形状的柔性蜂窝,并对该蜂窝结构的剪切力学性能分析方法进行研究。先将其等效为正交各向异性材料,采用代表体元法推导出十字形蜂窝的面内切变弹性模量的计算公式,同时还研究了切变模量与蜂窝形状参数的关系,并通过仿真分析和力学性能试验进行验证。结果表明,基于代表体元法对十字形柔性蜂窝的面内切变模量进行分析是合理有效的,推导出的理论公式可以指导蜂窝参数设计。     

基于累积线性法的一种柔性蒙皮设计

变体飞机的机翼需要能够光滑连续变形的柔性蒙皮,借鉴自然界蜜蜂筑巢的蜂窝,针对柔性蜂窝力学特性,采用CAD与CAE相结合的策略,以累积线性法为建模与计算手段,开展柔性结构几何大变形的非线性分析。对凯夫拉29、凯夫拉49两种柔性蜂窝和硅橡胶在不同组合的柔性蒙皮以及在不同蜂窝厚度的情况下,分别进行了数值计算对比工作。结果表明:单纯的硅橡胶,以及单纯的蜂窝式结构都不能满足变体飞机中柔性蒙皮的高承载、大变形和轻重量的需求;分别采用凯夫拉29和凯夫拉49与硅橡胶结合时,凯夫拉49材料的柔性蜂窝结构的法向承载能力要高于凯夫拉29蜂窝;另外,柔性蜂窝高度5 mm和壁厚1 mm时,法向承载能力很弱,增加高度的柔性蜂窝法向刚度有所改善。可以推知,在变体飞机特殊部位,用柔性蜂窝蒙皮代替传统硬蒙皮具有一定的可行性。     

变形翼面内变形的研究现状及关键技术

变形机翼作为未来飞机设计的重要发展方向之一，其机翼面内变形的研究已得到广泛的关注。本文分别从变展长、变掠角、变弦长、组合变形四个方面进行分析，阐述面内变形机翼的国内外研究现状，归纳总结变形机理及优缺点，分析其发展趋势。针对该领域的研究现状以及变形机翼的应用要求，提出变形机翼亟待解决的关键技术，包括变形蒙皮技术、变形机构、智能驱动器、传感器及控制网络，阐述各关键技术的应用要求，分析其现存问题，并对未来发展方向进行归纳；以期为面内变形机翼的设计和应用实现提供部分参考。     

变弯度后缘与常规舵面机翼的颤振主动抑制对比

后缘变弯度机翼的气动弹性建模与稳定性分析日益受到关注。为了探究变弯度后缘相比常规偏转舵面机翼颤振主动抑制的方法与特点，以一个小展弦比后缘变弯度机翼为对象，首先建立结构有限元模型，并引入变弯度后缘变形模态和常规舵面偏转模态，采用亚声速偶极子格网法计算非定常气动力；然后使用基于最小状态法的有理函数拟合进行频域到时域模型的转换，建立两种构型机翼的气动弹性模型，并在建模时考虑了变弯度后缘与常规舵面控制带宽的差异；最后利用线性高斯二次型方法设计控制律进行颤振主动抑制，分析对比两种控制方式的特性差异。结果表明：采用变弯度后缘的闭环系统能够将颤振临界速度提高22%，其提升效果优于常规舵面，所需舵面偏转峰值更小。     

柔性机翼后缘结构变形重构研究

<正>随着航空技术日新月异的发展,传统飞行器的开缝式后缘襟翼已不能满足军用及民用领域的更高要求。现代变体飞行器主要通过变面积、变后掠角和变弯度等方式实现飞行器结构连续变化。柔性机翼后缘是一种重要的柔性变体结构,它将传统开缝式后缘襟翼结构替换为可连续偏转的柔性材料,实现机翼后缘的连续变形,实现机翼减重、降油耗和提高气动性能等目标。在可连续偏转柔性机翼后缘,使用过程中相对于传统的机翼,会产生较大的弹性变形,因此必须对其变形进行实时的监测和重构,在     

In-plane corrugated cosine honeycomb for 1D morphing skin and its application on variable camber wing

A novel 0-Poisson’s ratio cosine honeycomb support structure of flexible skin is proposed. Mechanical model of the structure is analyzed with the energy method, finite element method (FEM) and experiments have been performed to validate the theoretical model. The in-plane characteristics of the cosine honeycomb are compared with accordion honeycomb through analytical models and experiments. Finally, the application of the cosine honeycomb on a variable camber wing is studied. Studies show that mechanical model agrees well with results of FEM and experiments. The transverse non-dimensional elastic modulus of the cosine honeycomb increases (decreases) when the wavelength or the wall width increases (decreases), or when the amplitude decreases (increases). Compared with accordion honeycomb, the transverse non-dimensional elastic modulus of the cosine honeycomb is smaller, which means the driving force is smaller and the power consumption is less during deformation. In addition, the cosine honeycomb can satisfy the deform- ing requirements of the variable camber wing.     

A compliant polymorphing wing for small UAVs

This paper presents the development of a novel compliant polymorphing wing capable of chord and camber morphing for small UAVs. The morphing wing can achieve up to 10% chord extension and ±20° camber changes. The design, modeling, sizing, manufacturing and mechanical testing of the wing are detailed. The polymorphing wing consists of one continuous front spar fixed to the fuselage and a rear spar on each side of the wing. Each rear spar can translate in the chordwise direction (chord morphing) and rotate around itself (camber morphing). A flexible elastomeric latex sheet is used as the skin to cover the wing and maintain its aerodynamic shape whilst allowing morphing. The loads from the skin are transferred to the spars using the compliant cellular ribs that support the flexible skin and facilitate morphing. Pre-tensioning is applied to the skin to minimize wrinkling when subject to aerodynamic and actuation loads. A rack and pinion actuation system, powered by stepper motors, is used for morphing. Aero-structural design, analysis and sizing are conducted. Performance comparison between the polymorphing wing and the baseline wing (non-morphing) shows that chord morphing improves aerodynamic efficiency at low angles of attack while camber morphing improves efficiency at high angles of attack.     

一种前后缘连续变弯度翼型气动特性分析

提出了一种基于厚度不变的翼型前后缘连续偏转变形规律,并以NACA0015翼型为例,实现了翼型变弯度的参数化。以柔性伸缩蒙皮支撑结构和机械结构实现了可连续光滑偏转后缘的变弯度翼型,验证了变形规律。以前后缘偏转角度为参数,计算并分析了各个变形状态下翼型扰流流场和气动特性,讨论了变形参数对气动特性的影响,研究了气动特性的产生机理。研究结果表明:在大迎角下,前缘偏转角对翼型失速有一定的抑制作用;在中小迎角范围内,翼型升阻比随着后缘偏转角的增大而增大,且不论迎角如何变化,总可以通过前后缘偏转来获得较高的升阻比。     

Comparative study of two lay-up sequence dispositions for flexible skin design of morphing leading edge

Morphing leading edge has great potential for noise abatement and aerodynamic efficiency improvement. The drooping effect is realized by bending of the flexible skin which encloses to form the leading edge. Since the flexible skin is often made of composite laminates of Glass Fiber Reinforced Plastics (GFRP), the lay-up sequences have become the determinant, which affects not only the morphing quality but also the manufacturing complexity. Two optimizing methods of lay-up sequences are comparatively studied. In the first method, the laminal quantities in 0°, ±45° and 90° vary independently, while in the second one, the concept of isotropic laminate unit [0/45/−45/90]s is employed and the unit quantity is the unique variable. Final evaluation demonstrates that for both methods there is insignificant impact to the overall morphing quality; however, specific concern is equally necessary for these two methods to the tip of the leading edge where the skin is at its minimum thickness and bears the most severe bending deformation. In terms of computational efficiency and post-processing labor, the second method has better performance.     

可连续光滑偏转后缘的变弯度翼型气动特性分析

以变弯度翼型为研究对象,计算了其六种外形的绕流流场,分析了不同的连续光滑变形翼型与传统偏转翼型的气动特性,讨论了变形参数对气动特性的影响,研究了气动特性的产生机理;与此同时,以形状记忆聚合物柔性蒙皮和机械结构实现了可连续光滑偏转后缘的变弯度翼型,并在风洞实验中测试了其气动特性。计算和实验结果表明:可连续光滑偏转后缘的变弯度翼型能改进传统主翼-简单襟翼翼型的气动特性和流场分离特性;可变形段范围、转轴位置、后缘偏转角度、后缘高度等变形参数对气动特性具有显著影响。     

Design and experiment of concentrated flexibility-based variable camber morphing wing

The morphing wing has a significant positive effect on the aerodynamic performance of the aircraft. This paper describes a leading-edge of variable camber wing with concentrated flexibility based on the geared five-bar mechanism. The driving points of morphing skin formed by the glass fibre composite sheet were optimized to make the skin deformation smooth. A geared fivebar kinematic mechanism rigidly connected to the skin was proposed to drive the leading-edge deformation. Besides, a new kind o...     

多段柔性变体扑翼飞行器设计

多段柔性变体扑翼模仿海鸥翅膀的复杂运动.观察海鸥翅膀的运动周期,设计了包含慢频率扑动、展向折弯、弦向扭转和结构柔性变形的扑翼模型,并应用准定常方法计算气动力,为该扑翼飞行器设计提供依据.在CATIA和3DMAX中设计多段柔性变体扑翼机的三维模型和运动模拟,制作样机进行飞行试验,研究其平飞、爬升、偏航等飞行姿态,结果表明升力和推力与数值计算结果吻合.相较于原有扑翼飞行器,多段柔性变体扑翼飞行器可以慢频率扑动飞行,调整扑翼形状.      

Optimization design of chiral hexagonal honeycombs with prescribed elastic properties under large deformation

Flexible chiral honeycomb cores generally exhibit nonlinear elastic properties due to large geometric deformation. The effective elastic moduli and Poisson’s ratio typically vary with an increase in deformation. Here, the size and shape optimization of the chiral hexagonal honeycombs was performed to keep the Young’s moduli and Poisson's ratio unchanged under large deformations. The size of the honeycomb unit cell and the position coordinates of the key points were defined simultaneously as design variables. The equivalent Young's modulus and Poisson’s ratio of chiral honeycombs were calculated through geometric nonlinear analysis. The objective was to minimize the allowable tolerance between the prescribed and actual properties within the range of the target strain. A genetic algorithm was then adopted. The optimal results demonstrate that the chiral honeycombs can maintain effective elastic properties that do not vary under large deformation. These results are meaningful to morphing aircraft designs.     

变体飞行器蒙皮材料与结构研究综述

变体飞行器最为重要的技术特征就是结构在变形过程中翼面保持光滑、连续和无缝,而变形蒙皮技术是保证该技术特征的关键。以变形方式和年代为主线详细地总结了变形蒙皮材料与结构的发展现状和未来趋势。从早期的"鱼鳞叠片"式传统滑动变形蒙皮到现在的复合式柔性变形蒙皮,可以看出复合化是变形蒙皮未来发展的必然趋势。