Dynamic Aeroelastic Performance Optimization of Adaptive Aerospace Structures Using Structural Geometric Nonlinearities

Abstract

This paper proposes a framework for the design optimization of geometric nonlinearities developed by active elements embedded in prestressable, statically indeterminant, truss-like aerospace structures for the purpose of attenuating their dynamic aeroelastic response under turbulent aerodynamic gust conditions. Dynamic aeroelastic responses are analyzed considering random power spectral density (PSD) gust with a continuous Davenport spectrum (DS) and tuned discrete gust (TDG) with a one-minus-cosine (OMC) wind excitation profiles. A genetic optimization algorithm (GA) is utilized to determine optimal prestress values through active element actuations for the purpose of tuning the geometric stiffness and, therefore, the modal response of the structure when exposed to gust excitations. In addition, a new simplified control metric for comparing active member locations is proposed. A case study is analyzed with this methodology to minimize the pointing error of a simplified antenna structure. Pointing error attenuations of 22.1% and 17.0% were found for the structure under DS mean wind speeds of 889 (349.95) and 2,778 cm/s (1,093.61 in./s), respectively. Using the same two operating cases with the TDG excitation profile resulted in the overall pointing error to be reduced by 36.8% and 37.0%, respectively. The adaptive nature of the presented methodology allows a single actuator layout to mitigate structural response for a variety of load cases, which is a large benefit over many traditionally passive techniques. This paper expands the existing usage of geometric nonlinearities to determine optimal active element location and actuations for given optimization objectives under realistic environmental loading conditions.