Decomposition of Mathematical Programming Models for Aircraft Wing Design Facilitating the Use of Dynamic Programming Approach

Aircraft designers strive to achieve optimal weight-reliability tradeoffs while designing an aircraft. Since aircraft wing skins account for more than fifty percent of their structural weight, aircraft wings must be designed with utmost care and attention in terms of material types and thickness configurations. In particular, the selection of thickness at each location of the aircraft wing skin is the most consequential task for aircraft designers. To accomplish this, we present discrete mathematical programming models to obtain optimal thicknesses either to minimize weight or to maximize reliability. We present theoretical results for the decomposition of these discrete mathematical programming models to reduce computer memory requirements and facilitate the use of dynamic programming for design purposes. In particular, a decomposed version of the weight minimization problem is solved for an aircraft wing with thirty locations (or panels) and fourteen thickness choices for each location to yield an optimal minimum weight design.

Parametric CAD Modelling of Aircraft Wings for FEA Vibration Analysis

Excessive vibration of aircraft wings during flight is harmful and may cause propagation of existing cracks in the material, leading to catastrophic failures as a result of material fatigue. This study investigates the variations of modal characteristics of aircraft wings with respect to changes in the structural configurations. We develop parametric Computer-Aided Design (CAD) models to capture new design intend on the aircraft wing architectures. Subsequent Finite Element Analysis (FEA) based vibration analysis is performed to study the effects of architecture changes on the wing’s natural frequencies and mode shapes. It is concluded that the spar placement and the number of ribs have significant influence on the wing’s natural vibration properties. Integrating CAD modelling and FEA vibration analysis enables designers to develop alternative wing architectures to implement design requirements in the preliminary design stage.

A Dynamic Programming Approach to the Design of Composite Aircraft Wings

A light and reliable aircraft has been the major goal of aircraft designers. It is imperative to design the aircraft wing skins as efficiently as possible since the wing skins comprise more than fifty percent of the structural weight of the aircraft wing. The aircraft wing skin consists of many different types of material and thickness configurations at various locations. Selecting a thickness for each location is perhaps the most significant design task. In this paper, we formulate discrete mathematical programming models to determine the optimal thicknesses for three different criteria: maximize reliability, minimize weight, and achieve a trade-off between maximizing reliability and minimizing weight. These three model formulations are generalized discrete resource-allocation problems, which lend themselves well to the dynamic programming approach. Consequently, we use the dynamic programming method to solve these model formulations. To illustrate our approach, an example is solved in which dynamic programming yields a minimum weight design as well as a trade-off curve for weight versus reliability for an aircraft wing with thirty locations (or panels) and fourteen thickness choices for each location.

Structural Design and Analysis of Small Flapping Wing Aircraft Based on the Crank Slider Mechanism

In this project,the miniaturization of the aircraft was realized under the premise of strong maneuverability,high concealability,and driving a certain load,and the flight mode and structural characteristics of birds were imitated.A small bionic flapping wing aircraft was built.The flapping of the wing was realized by the crank slider mechanism,and the sizes of each part were calculated according to the bionics formula.The wingspan was 360.37 mm,the body width was 22 mm,the body length was 300 mm,the wing area was 0.05 m^(2),the flapping amplitude was 71°.ADAMS software was used to simulate the dynamics of the designed aircraft,and the variation of flapping amplitude and angular velocity during the movement of the aircraft was obtained,which verified the feasibility of the mechanism.The prototype aircraft was made for flight test,and the designed bionic flapping wing aircraft achieved the expected effect.It provides a theoretical basis and data support for the design and manufacture of small flapping wing aircraft.

A novel posture alignment system for aircraft wing assembly

A novel 6-degree of freedom (DOF) posture alignment system, based on 3-DOF positioners, is presented for the assembly of aircraft wings. Each positioner is connected with the wing through a rotational and adsorptive half-ball shaped end-effector, and the positioners together with the wing are considered as a 3-PPPS (P denotes a prismatic joint and S denotes a spherical joint) redundantly actuated parallel mechanism. The kinematic model of this system is established and a trajectory planning method is introduced. A complete analysis of inverse dynamics is carried out with the Newton-Euler algorithm, which is used to find the desired actuating torque in the design and path planning phase. Simulation analysis of the displacement and actuating torque of each joint of the positioners based on inverse kinematics and dynamics is conducted, and the results show that the system is feasible for the posture alignment of aircraft wings.

Aeroelastic optimization on composite skins of large aircraft wings

This paper presents studies of aeroelastic optimization on composite skins of large aircraft wings subject to aeroelastic constraints and strength/strain constraints. The design variable for optimization was the ply thickness of the wing skin panels, and the structural weight was the objective function to be minimised. The impacts of three strength/strain constraints and the ply proportion of the wing skin panels on the optimization results are discussed. The results indicate that the optimal composite wings that satisfy different constraints have remarkable weight advantages over metal wing. High levels of stiffness can be achieved while satisfying the constraints regarding allowable design strains and failure criteria. The optimization results with variable-proportions indicate that wing skins with higher proportions of 0° plies from the root to the middle segment and ±45° plies outboard have a more efficient and reasonable stiffness distribution.

Adaptive Kalman Filter of Transfer Alignment with Un-modeled Wing Flexure of Aircraft

The alignment accuracy of the strap-down inertial navigation system （SINS） of airborne weapon is greatly degraded by the dynamic wing flexure of the aircraft. An adaptive Kalman filter uses innovation sequences based on the maximum likelihood estimated criterion to adapt the system noise covariance matrix and the measurement noise covariance matrix on line, which is used to estimate the misalignment if the model of wing flexure of the aircraft is unknown. From a number of simulations, it is shown that the accuracy of the adaptive Kalman filter is better than the conventional Kalman filter, and the erroneous misalignment models of the wing flexure of aircraft will cause bad estimation results of Kalman filter using attitude match method.

Studies on the influence of spar position on aeroelastic optimization of a large aircraft wing

Aeroelastic problems are encountered at the preliminary design stage of flexible wings for large aircraft.A three-dimensional finite element model of a high-aspect-ratio wing was built,and the influence of the front and rear spar positions on the results of the aeroelastic analysis and optimization was studied to improve the wing structure desgin.The most feasible and optimal solutions were effectively obtained by aeroelastic optimization.In particular,the position parameter of the front spar has a greater influence on the aeroelastic analysis and optimization than the rear spar.In addition,some key constraints became re-strictive leading to a rapid increase in the structural weight.Therefore,reasonable constraints were necessary for the oprimiza-tion of results.

EXPERIMENTAL RESEARCH OF THE CONFIGURATION OF WING－TIP DRAG REDUCTION FOR LIGHT AIRCRAFT

hree kinds of devices of drag reduction are presented swept wingtip,stage by stage swept wingtip and downbend wingtip. The effects of changing geometryparameters of the swept wingtip on the drag reducing are also presented. Wind-tunnelexperiment results indicate that a properly designed swept wingtip results in an incre-ment in induced efficiency of 4%～ 7% and that swept wingtip can increase longitudinalstatic-stability. Water-tunnel experiment results indicate that the reason for drag re-ducing of swept wingtip is that when the angle of attack is not zero, the strong end vor-tex of the wing is weakened by the combined effect of the leading edge and trailing edgevortices of the swept wingtip.

OPTIMAL DESIGN AND AERODYNAMIC CALCULATION OF WING CONFIGURATION OF CIVIL AIRCRAFT

An effective method of optimal design of wing configuration is provided. The SUMT (sequential unconstained minimization technique) method is a good technique for solving the nonlinear programming. The application of penalty in optimal design of wing configuration has been solved well. The present method for the aerodynamic calculation is the combination of both the nonlinear panel method and the suction analogy method of vortexlift spanwise distribution on large swept wing-tip. The calculation results are in good agreement with experimental data. According to the computation and experiment,the mechanism of the increased lift and reduced drag about the sheared wing-tip wing has been analyzed, and some opinions of interest are proposed.

Retarded Harrier Maneuver as a New and Efficient Approach for Fixed-Wing Aircraft to Achieve S/VTOL

Modern day VTOL fixed-wing aircraft based on quadplane design is relatively simple and reliable due to lack of complex mechanical components compared to tilt-wings or tilt-rotors in the pre-80’s era. Radio-controlled aerobatic airplanes have thrust-to-weight ratio of greater than unity and are capable of performing a range of impressive maneuvers including the so-called harrier maneuver. We hereby present a new maneuver known as the retarded harrier that is applicable to un/manned fixed-wing aircraft for achieving VTOL flight with a better forward flight performance than a quadplane in terms of weight, speed and esthetics. An airplane with tandem roto-stabilizers is also presented as an efficient airframe to achieve VTOL via retarded harrier maneuver, and detailed analysis is given for hovering at 45° and 60° and comparison is made against the widely adopted quadplane. This work also includes experimental demonstration of retarded harrier maneuver using a small remotely pilot airplane of wingspan 650 mm.

飞行器折叠翼展开冲击环境条件研究

带折叠翼飞行器在结构上与传统飞行器略有差异,其翼展开冲击环境条件的制定无相似型号及经验可参考。本文针对飞行器折叠翼展开冲击环境条件问题,通过分析五种条件制定方法,对不同样本量情况下飞行器折叠翼展开冲击环境进行研究,给出了该类型飞行器折叠翼展开冲击环境条件的制定方法。

涡轴-涡扇变循环发动机方案及性能匹配设计研究

针对旋转机翼式垂直起降高速巡航飞行器,提出了一种新概念结构形式的涡轴-涡扇变循环(TSFVCE)发动机,能够分别在涡轴和涡扇两种模态工作。首先对涡轴-涡扇变循环发动机的结构及工作模式进行了介绍,并建立基于变比热的部件级性能仿真模型;然后通过循环分析,确定发动机第二涵道比为3,Flade外涵风扇压比为1.98,第一涵道比为0.11,完成发动机设计点性能方案设计;最后分析了核心机驱动风扇(CDFS)可调机构对发动机性能影响机理,得出CDFS放气阀对发动机涡扇模态下的推力与涡轴模态下的功率影响较大,对涡扇模态的推力影响最大为61.5%,对涡轴模态的功率影响最大为33.3%,可利用此特性实现发动机在涡扇和涡轴模态下推力和功率输出的匹配。

机翼弯曲模拟系统的建模与仿真研究

某型飞机在飞行过程中,机翼将产生最大可达3米的变形,该变形将严重影响安装在飞机机翼上钢索传动装置的操控性能,同时考虑操控性能在真实飞行过程中的成本、难度、风险问题,构建了地面机翼弯曲模拟系统。首先,构建了由16套机构组成的全机翼半物理仿真模型,各机构均安装有一套位移伺服控制系统和一套角度伺服控制系统。然后对系统的角度控制及位移控制进行了建模、仿真研究,提出了有效的前馈和模糊控制相结合的控制策略。最后搭建了实验验证系统并进行了验证。结果表明:该系统设计合理,实用性强,满足钢索在机翼弯曲变形下的操控性能测试。

折叠翼飞行器气动弹性变体飞行仿真平台

折叠翼飞行器的变体过程伴随质量分布、刚度分布及气动载荷分布的大幅动态变化,是一个高度复杂的动力学过程。为实现该过程各种动力学问题的有效分析,基于共享内存技术开发了一套高性能的耦合计算程序,并在此基础上整合了Adams多体动力学计算软件、非定常气动力计算程序及飞行控制技术,搭建了折叠翼的气动弹性变体飞行仿真平台。基于该平台,对折叠翼进行了气动弹性分析和飞行变体过程仿真,验证了平台强大的计算和分析能力。

倾转机翼/旋翼机过渡姿态规划分析

针对带有倾转机翼段的新构型倾转旋翼机复杂的倾转过渡变构型过程,提出一种基于动量叶素理论的高速段倾转走廊边界计算方法。通过低速时机翼失速限制和高速时旋翼可用功率限制建立倾转过渡走廊计算模型,对比了传统构型倾转旋翼机和倾转机翼/旋翼机的倾转过渡走廊差别。对2种构型倾转旋翼机倾转过渡状态下前飞速度、机身迎角、旋翼桨距角姿态进行了对比分析。结果表明:带有倾转机翼段的倾转机翼/旋翼机具有更狭窄的倾转走廊,在短舱角0°状态,倾转机翼段占1/3展长的旋翼机相较于传统构型倾转旋翼机,倾转速度边界从39~57 m/s缩减到41.7~51.2 m/s,倾转操纵难度加大;在大于45°短舱角的倾转前期,同样的前飞速度和短舱倾转角状态下,倾转机翼/旋翼机机身迎角降低约2°,旋翼桨距角增大1°~4°,随着倾转过渡的完成,2种构型倾转旋翼机姿态差异逐渐变小。

考虑强风干扰的固定翼飞行器“神经元”飞行气动建模

大气环境中的风是影响飞行器实际飞行的主要动态环境干扰因素之一,强风干扰下的复杂空气动力学是固定翼飞行器安全稳定飞行面临的严峻挑战。为提高强风干扰下固定翼飞行器的环境适应能力,发展了一种基于深度元学习的创新固定翼飞行器“神经元”飞行气动建模方法,该方法采用相对于地面坐标系的变量进行描述,根据多元函数的切比雪夫级数理论,将气动力和气动力矩函数分解为不同变量函数的乘积和,通过生成对抗网络技术构建强风干扰下飞行器空气动力模型的共性基函数模型,进而预测飞行器在飞行过程中受到的气动力(矩)。研究结果表明,文章建立的固定翼无人机空气动力共性基函数模型准确,可以较好地预测未知风况条件下飞行器的气动力与气动力矩,为实时空气动力学建模的迁移应用奠定良好基础。

仿鸟类扑翼飞行器研究进展

仿生扑翼飞行器有着优异的气动性能和灵活的飞行能力,在军民领域均有广泛的应用前景,学者们在原理样机研制、扑翼气动机理、驱动机构、飞行控制等多领域取得了一系列重要进展.本文从总体设计方法、驱动机构设计与优化、气动机理等方面综述了仿鸟类扑翼飞行器技术的发展历程与研究进展.首先,从扑翼总体设计方法入手,总结了仿鸟类扑翼飞行器仿生构型,归纳了总体设计参数估算方法;其次,综述了多种构型曲柄连杆机构在扑翼驱动中的应用与优缺点;接着总结了扑翼气动机理研究的实验方法与数值计算方法,分析了不同扑翼气动算法针对不同应用场景在计算成本和准确度方面的优劣情况;最后,对仿鸟类扑翼飞行器系统设计研究现状进行总结,针对原理样机研制过程提出展望.

飞机前缘缝翼精准装配技术研究

该文主要探讨飞机机翼前缘与缝翼的数字化装配精准控制技术。从飞机的装配技术难点出发,结合机翼前缘与缝翼的数字化装配技术细致分析,深入讨论装配协调的各种方法及技术手段。该文最后提出一系列数字化装配协调的实施措施。期望此研究能为提升我国在飞机部件装配协调领域的技术水平提供有益的参考。