Nonlinear aeroelastic analysis of a HALE aircraft with flexible components

Abstract

In this study, a full HALE (high altitude, long endurance) aircraft, nonlinear, aeroelastic analysis is being performed. Nonlinear, general, flexible, Euler–Bernoulli beam equations are being used to model the wings and the tails, and the linear, Euler–Bernoulli beam equation is used to model the fuselage. A unified formulation for modeling flexible components dynamics based on kinetic energy coupling is also being employed to model the behavior of fully flexible aircrafts. Aerodynamic forces and moments on the wings and horizontal tails are modeled based on the Wagner's function and the Jones approximation. The results of flutter properties and nonlinear time response of the limit cycle oscillations are validated. The time response, the flutter boundary, the post flutter limit cycle oscillations of wings and tails, and the vibration behavior of the fuselage are investigated, and the effect of the fuselage rigidity on the system behavior is examined. The results show that to accurately predict the aeroelastic behavior, a full aircraft analysis is necessary, especially when the amount of the bending and the torsional rigidity of the fuselage is close to the amounts of the wings and tails.