Multibody Dynamic Approach of Flight Dynamics and Nonlinear Aeroelasticity of Flexible Aircraft

Abstract

The flight and structural dynamics of a very flexible aircraft, especially while maneuvering, aremore tied together than those of conventional aircraft. Hence, it is necessary to study the coupled effects of flight dynamics, aeroelasticity, and control. This paper presents a multibody dynamic approach in which the flexible aircraft is modeled as a feedback-controlled multibody system under aerodynamic forces. The governing equations of the system are established by combining the equations of amultibody system, the ONERAaerodynamicmodel, and that of controls. The trim state of the flexible aircraft is solved using a dynamic relaxation method around which the perturbation equation is derived and solved for system stability. To demonstrate the advantage of multibody dynamics inmodeling the constrained system undergoing large displacements and rotations, the proposed approach is applied to the flexible aircraft in level flight and in the circling and dive–loop–climbmaneuvers. Beyond the flutter boundary, the limit cycle oscillations response is solved, in which several interesting aspects of flexible aircraft flutter are revealed. In the end, the jointflutter andattitude control is used to suppressflutter response and stabilize attitude.