Computer-augmented preliminary design of aircraft wing structures

A computer system to aid in the preliminary design of aircraft wing structures for minimum weight is described. The system was developed to utilize effectively the best attributes of both computers and the human mind in the iterative process of analyzing highly redundant trial structures and using these results to select new trial structures with the objective of minimizing weight. The computer is used for the routine data processing, and the designer performs those tasks which require judgement and intuition. Cathode ray tube graphical displays are provided for checking input data and for evaluating results. From given basic information on the wing structure, loads, and material properties, a finite element model is developed, analyzed, modified to eliminate violations of design criteria, and optimized to obtain the structural configuration of least weight. The optimization proceeds automatically, but the designer may monitor progress with the aid of tabular and graphical displays and modify the direction in which the optimization is proceeding. The impetus for this work was provided by a need for such a system in teaching structural design to aeronautical engineering students. The modular system was developed for the Control Data Corporation 6400/6500 computer installation at Purdue University using the Purdue Interactive Remote Access Terminal Environment (PIRATE).     

Optimal design of wing structures with substructuring

An iterative method for optimal design of large scale structures that incorporates the concept of substructuring is extensively applied to wing-type structures to demonstrate its generality, effectiveness and efficiency. Optimum designs for several wing-type structures are obtained and compared with results available in the literature. It is shown that considerable efficiencies can be achieved by integration of the substructuring concept into a structural optimization algorithm.     

Autonomous experimental design optimization of a flapping wing

Applying evolutionary computation to the optimization of aerodynamic properties of shapes and structures usually involves computational fluid dynamics simulations. The simulation of the physical properties of a possible solution has various advantages. However, like in all simulations various restrictions and simplifications exist even for the most advanced simulation methods. Furthermore, the high computational demand very often does not allow high fidelity simulations together with numerical optimization methods. In this paper, we present an approach to combine evolutionary algorithms with physical measurements in order to allow an experiment-based evaluation of solutions. In this way, we can overcome the limitations connected to simulations of physical environments. We present the approach for a set-up in which the geometry of a flapping wing is optimized in order to find optimal configurations for various quality criteria.     

Integrated design support system

The integrated design support system (IDS) is a concept for capturing the critical technical engineering information necessary to perform the functions of maintenance, modification, repair, and reprocurement of Air Force weapon systems. The program will first construct an architecture to define the required information. Next, IDS will construct prototype software to acquire, store, distribute, and perform configuration management on the data. The program will conclude with software simulation of the full-scale IDS system operating in a production environment to determine performance characteristics together with development and operatonal costs for the system.     

Aircraft morphing wing design by using partial topology optimization

A morphing wing concept has been investigated over the last decade because it can effectively enhance aircraft aerodynamic performance over a wider range of flight conditions through structural flexibility. The internal structural layouts and component sizes of a morphing aircraft wing have an impact on aircraft performance i.e. aeroelastic characteristics, mechanical behaviors, and mass. In this paper, a novel design approach is proposed for synthesizing the internal structural layout of a morphing wing. The new internal structures are achieved by using two new design strategies. The first design strategy applies design variables for simultaneous partial topology and sizing optimization while the second design strategy includes nodal positions as design variables. Both strategies are based on a ground structure approach. A multiobjective optimization problem is assigned to optimize the percentage of change in lift effectiveness, buckling factor, and mass of a structure subject to design constraints including divergence and flutter speeds, buckling factors, and stresses. The design problem is solved by using multiobjective population-based incremental learning (MOPBIL). The Pareto optimum results of both strategies lead to different unconventional wing structures which are superior to their conventional counterparts. From the results, the design strategy that uses simultaneous partial topology, sizing, and shape optimization is superior to the others based on a hypervolume indicator. The aeroelastic parameters of the obtained morphing wing subject to external actuating torques are analyzed and it is shown that it is practicable to apply the unconventional wing structures for an aircraft.     

基于CATIA二次开发的翼面结构参数化设计

为解决翼面结构参数化设计的问题,研究了翼面结构各组成元件的个数、位置、截面尺寸参数化描述的方法.基于这些参数研究如何通过CATIA二次开发方式自动生成翼面结构三维图以及从总体模型获取机翼外形参数.在对翼面结构参数化描述的基础上,应用Visual Studio环境下CATIA二次开发技术,结合VB和C++语言混合编程,实现翼面结构的参数化设计.     

Automated optimum design of wing structures: A probabilistic approach

The optimization of aircraft wing structures is presented by considering the dynamic stresses developed during landing impact and gust load conditions. The random nature of the sinking speed and the forward velocity at the instant of contact is considered in the calculation of landing stresses. The vertical velocity due to gust is treated as a stochastic process for the computation of gust-induced stresses. The optimum designs of a symmetric double wedge airfoil, based on beam type of analysis, and a supersonic airplane wing, based on finite element analysis, are considered to illustrate the procedure. A graphical procedure is used in the case of the double wedge airfoil, and nonlinear programming techniques are used in the case of the supersonic wing, for finding the optimum solutions.     

Automated structural design and analysis of advanced composite wing models

The design of a composite wind tunnel model has demonstrated the ability to tailor the response of a composite structure to provide desired static and dynamic characteristics. This was possible because the strength and stiffness properties of composite structures can be controlled through selection of materials and lamination patterns. To take maximum advantage of the capability, efficient computer procedures are being developed for the design and analysis of composite structures. A finite element procedure and a direct Rayleigh-Ritz procedure, specialized for the preliminary analysis of wing-type structure, are discussed. The use and accuracy of these procedures have been demonstrated on a low cost, low risk basis in the design and analysis of a composite wind tunnel model and in test-theory correlation for static and dynamic response. Material selection, intermediate design decisions, fabrication, testing for natural modes and frequencies, and testing for influence coefficients for the wind tunnel model are discussed.     

综合航电开放式软件设计技术

综合航电开放式软件设计技术是新一代航电系统支持平台机载实时容错分布式计算机系统的重点,它的设计直接或间接地关系到新一代综合航电系统的性能和成本.针对先进综合航电系统的特点、性能要求,对目前机载计算机软件系统存在的可靠性、安全性低,不易移植,成本高,层次分割不清晰,功能独立性差,对系统容错支持能力弱等缺陷,提出了"三层栈结构"的软件设计新思想,通过标准接口(物理接口和逻辑接口)使得层与层,模块与模块之间得以分开,实现了功能模块化、软硬件隔离性、软件的再利用性、可剪裁性、易维护性,以适应不断增长的航空电子系统任务能力需求,为新一代航电系统支持平台机载实时容错分布式计算机系统的开发、研制提供了可靠的保证.     

Self-tuning regulator design for adaptive control of aircraft wing/store flutter

The application of the self-tuning regulator concept to adaptively control aircraft wing/store flutter instability is described. A simple design based on a reduced-order aircraft model has been successfully tested on a high-order simulation of an advanced aircraft, and performance was found to be comparable to another design using on-line maximum likelihood identification of plant parameters. The main advantage of the self-tuning regulator is its simplicity, while the main disadvantage is the inadequacy of prior performance guarantees.     

Integrated optimal structural and vibration control design

An integrated design procedure which is composed of structural design, control design, and actuator locations design is proposed in this paper. First, a composite objective function, formed by a structural and a control objective, is optimized in steady state through the homogenization design method. Then an independent modal space control algorithm (IMSC) is performed on this optimal structure to reduce the dynamic response. Finally, to minimize the control force while still obtaining the same modal response for the controlled modes, the optimal choice for actuator locations is discussed.Part of this paper was presented in the First World Congress of Structural and Multidisciplinary Optimization (held in Goslar, Germany, May 28–June 2, 1995).     

Integrated analysis and design in stochastic optimization

An integrated analysis and design approach for stochastic optimization of structures is presented. The proposed procedure employs a first order second moment (FOSM) method for evaluating the constraints associated with structural safety.Two variants of the new approach are presented. The idea is to integrate the nested iterative procedures for constraint evaluation and optimum search into one. The new approach is applied to simple design examples. The results are compared to those obtained by classical stochastic optimization using the FOSM method to evaluate the constraints. Both methods are robust to a satisfactory degree and substantially reduce the computational effort.     

Integrated layout design of supports and structures

Based on the previously proposed techniques for the integrated layout optimization of multi-component system, this paper is to demonstrate further developments and applications of the related techniques in the integrated layout design of supports and structures. The design procedure mainly consists of two parts. Firstly, the layout of the supports is described with the positions of movable support components on the specified boundary of the design domain. These components are partially embedded into the design domain and subjected to the applied boundary conditions. Secondly, the layout optimization of the support components and the structure is carried out. Locations of the support components and the pseudo-densities defined on the density points are assumed as geometrical and topological design variables, respectively. Geometrical constraints are imposed to avoid the overlap of multiple components. The technique of embedded meshing is employed to adapt the topology optimization to the variation of the finite element mesh caused by the component movement. Varieties of numerical examples are finally tested to validate the proposed method. Both surface load and self-weight load are taken into account. More complexities of partially supported components are introduced in the presented examples.     

Parallelized structural topology optimization and CFD coupling for design of aircraft wing structures

A set of structural optimization tools are presented for topology optimization of aircraft wing structures coupled with Computational Fluid Dynamics (CFD) analyses. The topology optimization tool used for design is the material distribution technique. Because reducing the weight requires numerous calculations, the CFD and structural optimization codes are parallelized and coupled via a code/mesh coupling scheme. In this study, the algorithms used and the results obtained are presented for topology design of a wing cross-section under a given critical aerodynamic loading and two different spar positions to determine the optimum rib topology.     

Integrated distributed intelligent system for process-control system design

In process-control system design, the Computer Aided Design (CAD) techniques have evolved a new generation of design techniques. This also paves the way for implementing Computer Integrated Manufacturing Systems (CIMS). However, the key issue to accomplishing the objectives in CAD is the automation of conceptual design. This paper first introduces the fundamentals of conceptual design for process-control system design. Then, a strategy to solve the problems in conceptual design is proposed. The associated system configuration and software implementation platform for developing intelligent systems for process control system design are presented. Finally, an application case is studied.     

面向动态三维迷宫的综合奖励设计

动态三维迷宫是较为困难的、具有不确定性和不完全信息的强化学习任务环境,使用常规奖励函数在此环境中训练任务,速度缓慢甚至可能无法完成。为解决利用强化学习在动态迷宫中寻找多目标的问题,提出一种基于事件触发的综合奖励方案,该方案将三维迷宫中各种行为状态表达为各种事件,再由事件驱动奖励。奖励分为环境奖励和内部奖励,其中环境奖励与三维迷宫任务直接相关,含有体现任务目标的节点奖励和任务约束的约束奖励。内部奖励与智能体学习过程中的状态感受相关,含有判断奖励和心情奖励。在实验中,综合奖励的性能均值相较于改进奖励提升54.66%,结果表明,综合奖励方案在提高完成任务满意度、增强探索能力、提升训练效率方面具有优势。     

Integrated design of fault detection systems in time-frequencydomain

Problems related to the integrated design of robust fault detection (FD) systems are studied. First, it is revealed that due to the time window introduced to realize the 2-norm based evaluation function, an optimal design of a FD system with the 2-norm based evaluation function may not ensure the expected optimal performance when the system is realized in real applications. To solve this problem, an integrated design method of FD systems using the absolute value of residual signal as evaluation function is then proposed. It leads to a residual generator which is much easier to be realized. Different from the usual 2-norm based approaches whose mathematical basis is the relationship between the energy of the output and input signals of a dynamic system, a relationship between the instant power of the output signal and the energy of the past input signal of a dynamic system is established and further used for FD system design. Another new kind of evaluation function based on the absolute value of wavelet transform of residual signal and the corresponding integrated design approach for FD systems are further proposed     

Integrated design and collaborative engineering of fabric structures

The design of fabric structures incorporates specfic aspects due to the tight interdependency between geometric, mechanical and manufacturing data used by the different professional partners. This is highlighted through the analysis of the various steps of the design process. A design approach, that takes into account the various actors, their knowledge and the techniques available within each of the previous fields has been set up.This approach relies on the identification of the flow of information and on the organization of data sets that are compatible with the design process breakdown into tasks in order to preserve their integration. Approximation methods are associated with some of this information to create design phases adapted to each actor through software tools implementing various modelling processes. The form finding process, the mechanical analysis of the structure, the determination of cutting patterns are examples of such modelling processes. The surface model of the fabric structure is one of such sets of data which has been identified and used to preserve the integration of the design process.Associated with the integrated design architecture, a collaborative environment helps to set up communication between some of the actors according to the design process organization. This environment acts as a complementary tool to help seeking compromises among the actors participating in a given phase of the design process. The communication tools work on a distributed architecture in such a manner that dialogue objects are shared among the actors.     

Integrated design of workcells and unidirectional flowpath layout

In manufacturing cells layout design with a unidirectional flow system, the accurate distance between two workcells can be uncovered with both the determination of IO port locations after the layout design of the cell with its orientation and the unidirectional flowpath layout design. This paper presents the method to obtain a global solution for manufacturing workcells and unidirectional flowpath layout design (ICFLD) with consideration of IO ports of workcells. The flow distance between two workcells is calculated from output port of one workcell to input port of the other workcell through the unidirectional flowpath layout. A zero-one integer programming model is developed for the ICFLD problem. And a heuristic algorithm for the ICFLD problem is developed by decomposing the ICFLD problem into two subproblems and iteratively and alternately solving the decomposed subproblems. Computational experiments are performed and its results are analyzed.