Investigation of Limit Cycle Response of Aerodynamic Surfaces with Structural Nonlinearities.

Abstract

Abstract : Aerodynamic surface design must often account for the presence of structural nonlinearities induced by freeplay in the support structure and/or control actuators. During this study, application of asymptotic expansion methods to predict the limit cycle behavior of aerodynamic surfaces with; structural nonlinearities was investigated. Two basic types of nonlinearities, freeplay and preload, were introduced at the aerosurface support structure and the resulting limit cycle behavior analyzed. The asymptotic expansion method was used to derive a relationship between the parameters characterizing the structural nonlinearity and the amplitude and frequency of the limit cycle response. The results of this investigation show that the asymptotic solutions accurately predict the stationary limit cycle behavior when compared with numerical simulation and describing-function analyses for the nonlinearities considered. The influence of higher harmonics on the predicted limit cycle response were also observed when higher order perturbation solutions were obtained. This study demonstrates the applicability of the asymptotic expansion method in accounting for the influence of structural nonlinearities in the limit cycle analysis of aerodynamic surfaces.