Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Investigation of the effects of structural nonlinearities on aeroelastic LCOs
Submission Author:
Lucas Pereira Resende , DF
Co-Authors:
Lucas Pereira Resende, Polliana Martins
Presenter: Lucas Pereira Resende
doi://10.26678/ABCM.COBEM2023.COB2023-1991
Abstract
Aeroelasticity deals with the study of the interaction between aerodynamic forces and structural dynamics, being crucial for the safety, performance, and efficiency of aerospace vehicles. Some aeroelastic phenomena, if not adequately addressed, can cause structural deformations that may lead to structural failure or performance loss. In this context, the importance of considering nonlinear effects in the study of aeroelasticity has become more evident with the advancement of aerospace systems, which are increasingly lighter and have challenging geometries. Therefore, this study proposes the analysis of the effects of structural nonlinearities, such as cubic stiffness, in an aeroelastic model of a straight rectangular wing with three degrees of freedom (bending, torsion, and control surface torsion). The model was initially analyzed in the classical linear domain of frequency, using the eigenvalue solution to calculate the critical flutter speed, natural frequencies, and associated damping. Along with the straight wing model, an aerodynamic model using strip theory simplification was used. The critical speed was calculated and compared with results from the literature. Then, the analysis proceeded in the time domain, using the 4th order Range-Kutta integration method to integrate the equations of motion and visualize the oscillation amplitudes of the treated degrees of freedom. A nonlinear model in the time domain was constructed by introducing a structural nonlinearity (cubic stiffness) in the model's stiffness. The presence of nonlinearities in the stiffness of the three degrees of freedom was evaluated. Based on the analysis of the results, it was observed that by introducing cubic stiffness in the wing's torsional mode, there was an increase in damping at the critical velocity of the linear model. Various nonlinear coefficients were tested, and the responses were compared with the linear case to highlight the differences in the treated values and the importance of including nonlinear behavior to detect Limit Cycle Oscillations (LCOs) and critical behaviors.
Keywords
Aeroelasticity, nonlinear aeroelasticity, Flutter, limit cycle oscillations
