Multibody Dynamics for the Coupling of Aeroelasticity and Flight Mechanics of Highly Flexible Structures

Abstract

Multibody simulation has been shown to be a valuable tool for many aerospace applications, being especially advantageous for the representation of systems with complex mechanical components and large rigid body motion. Typical applications are therefore landing gear design and aircraft ground dynamics, design of aircraft control surface actuation, and helicopter analysis. In addition, the medium level of complexity of typical multibody applications make it a suitable tool for the integration in aircraft pre-design. In practically all applications mentioned above aeroelastic effects play a major role. The addition of reliable aerodynamic models in addition to the existing interface for complex elastic structures has therefore been a major activity in the DLR Institute of Aeroelasticity during the past years, ranging from strip-theory and lifting-line-type models to interfaces with high-end CFD tools. Aeroelastic analyses using MBS have been shown e.g. for loads calculation of civil and military aircraft. A major advantage of using multibody dynamics for aeroelastic applications is the straight-forward introduction of flight mechanics into the aeroelastic simulation. The full advantage of using a complex multibody tool becomes most evident for systems with large rotations like helicopters or tilt rotors and for aircraft with large elastic deflections. The paper presents applications for a coupled aeroelastic and flight mechanic simulation for a civil transport aircraft and a light and very flexible high altitude, long-endurance configuration. The paper treats the introduction of the single disciplines (e.g. structures, aerodynamics) into the MBS-simulation and describes the coupling procedures. Typical problems, like load analysis for various structural properties, a preliminary wing sizing loop and the influence of low-frequency aeroelastic deformations on flight mechanics are discussed.