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Dynamic characterization of aeroelastic systems in the presence of multiple combined nonlinearities: Numerical study and experimental validation

Grant number: 19/05410-9
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): November 01, 2019
Effective date (End): October 31, 2021
Field of knowledge:Engineering - Aerospace Engineering - Flight Dynamics
Principal Investigator:Flávio Donizeti Marques
Grantee:José Augusto Ignácio da Silva
Home Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Aeroelastic systems can easily exhibit a non-linear behavior, due to the great demand of sources of nonlinearitiesexisting in them. The behavior of these systems in the presence of non-linearities is totally differentfrom that predicted by linear techniques commonly used in the definition of the flight envelope of the aircraft, sothe system can present unstable regions of operation even being within the flight envelope defined by lineartechniques, because they are not able to predict the dynamic behavior of the system in the presence ofnonlinearities. The sources of structural nonlinearities are predominant in these systems, and thus a great effortis made by the scientific community to study dynamic behavior and to work on the formulation of mathematicalmodels capable of predicting the nonlinear behavior of the latter. In this context, this proposal is focused on thestudy and dynamic characterization of aeroelastic systems in the presence of structural nonlinearities combinedboth in effect and also about their presence in the degrees of freedom of the aeroelastic system, since in practicesuch configuration is verified. The typical section model of a 3 DOF airfoil is used in conjunction with a linearsubsonic non-stationary aerodynamic model for arbitrary movements. The structural non-linearities of free-playand friction on the control surface, cubic stiffness (hardening) associated with pitch movement and combinedfree-play with hardening on the control surface are studied. The methodology used in the dynamic characterization of thesystem is based on the analysis of the Bifurcation Diagrams to be constructed by the results obtained bynumerical integration of equations of motion and based on the analytical approximation obtained by the MultipleScale Method (MMS). Experimental tests will be conducted to validate the results obtained with the mathematicalmodels developed.