AN APPROACH TO INTEGRATED AEROSERVOELASTIC TAILORING FOR STABILITY (AEROELASTICITY, MULTIDISCIPLINARY DESIGN, STRUCTURAL OPTIMIZATION, UNSTEADY AERODYNAMICS)
Abstract
A fundamental study of the problem of combined structural and control design for aeroelastic behavioral objectives, called "integrated aeroservoelastic tailoring", is conducted. First, behavioral characteristics of two idealized aeroservoelastic models are studied. These models are a 3 degree-of-freedom airfoil and a 4 degree-of-freedom aircraft idealization, the latter incorporating the 3 degree-of-freedom airfoil elastically attached to a fuselage with freedom in body pitch. Structural design parameters are the shear center and airfoil position. control synthesis is accomplished with optimal steady-state linear quadratic regulator theory. Control design parameters include the control design speed and elements of the output weighting matrix in the quadratic cost function used in the control synthesis. Second, aeroservoelastic tailoring is posed as a multi-disciplinary optimization problem to which is applied multilevel linear decomposition, breaking the aeroservoelastic system down into structural and control subsystems. For the present study, the design objective is a maximized stable airspeed envelope with the subsystem designs constrained to be optimal in some way. The control subsystem is the optimal steady-state linear quadratic regulator. The structural subsystem is not modeled in detail. An iterative design technique is then applied to the two models. Results show that the technique yields optimally controlled configurations with superior stability boundaries. The technique also provides a rational means for determining changes in structural and control design parameters to effect desired changes in system performance.
Degree
Ph.D.
Subject Area
Aerospace materials
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