The increasing complexity of engineering systems has sparked increasing interest in multidisciplinary optimization (MDO). This paper presents a survey of recent publications in the field of aerospace where interest in MDO has been particularly intense. The two main challenges of MDO are computational expense and organizational complexity. Accordingly the survey is focused on various ways different researchers use to deal with these challenges. The survey is organized by a breakdown of MDO into its conceptual components. Accordingly, the survey includes sections on Mathematical Modeling, Design- oriented Analysis, Approximation Concepts, Optimization Procedures, System Sensitivity, and Human Interface. With the authors'' main expertise being in the structures area, the bulk of the references focus on the interaction of the structures discipline with other disciplines. In particular, two sections at the end focus on two such interactions that have recently been pursued with a particular vigor: Simultaneous Optimization of Structures and Aerodynamics, and Simultaneous Optimization of Structures Combined With Active Control.

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Multidisciplinary Aerospace Design Optimization: Survey of Recent Developments

The increasing complexity of engineering systems has sparked increasing interest in multidisciplinary optimization (MDO). This paper presents a survey of recent publications in the field of aerospace where interest in MDO has been particularly intense. The two main challenges of MDO are computational expense and organizational complexity. Accordingly the survey is focussed on various ways different researchers use to deal with these challenges. The survey is organized by a breakdown of MDO into its conceptual components. Accordingly, the survey includes sections on Mathematical Modeling, Design-oriented Analysis, Approximation Concepts, Optimization Procedures, System Sensitivity, and Human Interface. With the authors' main expertise being in the structures area, the bulk of the references focus on the interaction of the structures discipline with other disciplines. In particular, two sections at the end focus on two such interactions that have recently been pursued with a particular vigor: Simultaneous Optimization of Structures and Aerodynamics, and Simultaneous Optimization of Structures Combined With Active Control.

/pdf/multidisciplinary-aerospace-design-optimization-survey-of-ghzjxaiur6.pdf

Multidisciplinary aerospace design optimization: Survey of recent developments

Aeroelastic instabilities are among the factors that may constrain the flight envelope of aircraft and, thus, must be considered during design. As future aircraft designs reduce weight and raise performance levels using directional material, thus leading to an increasingly flexible aircraft, there is a need for reliable analysis that models all of the important characteristics of the fluid-structure interaction problem. Such a model would be used in preliminary design and control synthesis. A theoretical basis has been established for a consistent analysis that takes into account 1) material anisotropy, 2) geometrical nonlinearities of the structure, 3) unsteady flow behavior, and 4) dynamic stall for the complete aircraft. Such a formulation for aeroelastic analysis of a complete aircraft in subsonic flow is described. Linear results are presented and validated for the Goland wing (Goland, M., The Flutter of a Uniform Cantilever Wing, Journal of Applied Mechanics, Vol. 12, No. 4, 1945, pp. A197-A208). Further results have been obtained that highlight the effects of structural and aerodynamic nonlinearities on the trim solution, flutter speed, and amplitude of limit-cycle oscillations. These results give insight into various nonlinear aeroelastic phenomena of interest: 1) the effect of steady-state lift and accompanying deformation on the speed at which instabilities occur, 2) the effect on nonlinearities in limiting the amplitude of oscillations once an instability is encountered, and 3) the destabilizing effects of nonlinearities for finite disturbances at stable conditions.

Nonlinear Aeroelastic Analysis of Complete Aircraft in Subsonic Flow

Fixed membrane wings for micro air vehicles: Experimental characterization, numerical modeling, and tailoring

At the end of the e rst century of manned, powered e ight, it is worthwhile to look backward to understand how innovation in airplane design required developments in aeroelasticity and how aeroelasticity has played a role in shaping the e rst 100 years of aircraft design. The insights gained will help to predict how and where aeroelasticity and aeroservoelasticity will ine uence the future development of efe cient, more capable, innovative air vehicles, and dee nethe needs fortechnology and tools to enable this future. By dee nition, all new aircraft begin as unconventional to a certain extent. Designs that never see universal use remain curiosities, but still help our questforbettervehiclesandguidethedevelopmentofanalysis, design, and testing tools. Innovative, nontraditional designsaffected by aeroelasticconsiderations haveincluded obliquewing aircraft, forward-swept wing aircraft,Xwings,e ying wings, andlargejoined wings. Designsthat wereunusually innovativeat thetimeoftheirintroduction but later became widespread include the swept-back wing jet, the T-tail, and the e y-by-wire control cone gured vehicle. Control and exploitation of aeroelasticity depends on the continued development of new materials, new structuralandaerodynamicconcepts,sensors,actuators,andactivecontroltechniques.Suchdevelopmentsmustbe accompanied by properintegratedanalysis/designtools,and,most importantly, by thesamehumaninquisitiveness and creativity that has driven aircraft design for over a century. This paper uses the history of nonconventional airplane cone gurations to review some of the steps taken during the past century to establish aeroelastic effects as integrated design features that must be anticipated, controlled, and exploited. The paper goes on to discuss the potential impact of past lessons on emerging airplane cone gurations currently in various stages of study and development.

Aeroelasticity of Nonconventional Airplane Configurations-Past and Future

Aeroelastic tailoring technology is reviewed with reference to the historical background, the underlying theory, current trends, and specific applications. The specific application discussed include the Transonic Aircraft Technology program, an Advanced Design Composite Aircraft, the Wing/Inlet Advanced Development program, and the forward-swept wing. Finally, the future of aeroelastic tailoring and the development of an aeroelastic tailoring analysis and design tool under the Automated Strength-Aeroelastic Design program are examined.

Terrence J. Hertz

Papers

Aeroelastic tailoring - Theory, practice, and promise

Aeroelastic tailoring - Theory, practice, and promise