Multibody Dynamics of Aeromechanical Systems

Abstract

Gliding flight is frequently treated as a reduced problem in rigid body aerodynamics, but many natural and engineered gliders undergo internal shape change, appendage motion, and coupled body deformation that substantially alter their dynamics. These features make gliding a problem that lies at the intersection of biomechanics, aerodynamics, multibody dynamics, nonlinear dynamical systems, and control. Although important progress has been made within each of these areas, the development of a unified framework that connects them remains limited. This dissertation aims to contribute to such a framework by examining how internal motion and geometry change influence the dynamics, stability, and control of gliding systems across both biological and engineering contexts. To this end, the dissertation studies several related manifestations of coupled glide dynamics. It first investigates the role of tail motion in gliding lizards, showing that the tail contributes to longitudinal response through both inertial and aerodynamic mechanisms and thereby influences pitch behavior and stability. It then considers lateral aerodynamic effects through the analysis of side force in textit{Draco} glides, demonstrating that glide motion is inherently three dimensional and that its aerodynamic response depends on both configuration and time varying kinematics. The work further develops a three dimensional dynamical systems framework for passive gliding, in which terminal velocity manifolds and separatrix structures organize glide trajectories and provide a geometric interpretation of distinct descent behaviors. Overall, the dissertation shows that gliding systems are most naturally understood as coupled multibody dynamical systems in which internal geometry and appendage motion play a fundamental role in force production, stability, and control. In doing so, it contributes a unified perspective that connects biological gliding, dynamical systems analysis, and morphing aircraft design.